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(1)Molluscan. Fauna. in. Southern. the. Mioeene. the. of. Part. Aichi. Morozaki. Chita. of. Prefecture,. Group. Peninsula,. Japan. By. Tokio. SIIIKAMA. Tomoki. and. EASE*. Abstract Tbe. Portlandia. is. Peninsula two. species, the. species,. new. Miocene. the. of. (Hataiyoldia). Chita. of 35. fauna. molluscan. Fauna,. tokunagai. described. from. of the. Group,. southern has. wbicb. is distributed.. The. (1973), and (1955, 1960) field.. this. the. T.. the. Peninsula. The. 1974. during. University, it.. did. he. and. of the. Morozaki. study geologlCal to 1975 for his. of the. valuable. fauna. writers. help. and. Prof.. T.. Prof.. Y.. 1wASAKI. K.. OzAKI *. was. the. HANAI,. Fisheries. Geological. R.. paper to. is to. deposited, to. wish. based express. Also,. advice. Prof.. K.. Of Kumamoto Laboratory, MAJIMA. Of the. Institute,ロniversity. the. the. on. of. Tokyo.. at. Of the Dr. Of. to. Group. and. Series. but. the. of Chita. other. in. fossils. characteristics the. wbicb. marine. molluscs.. Mr.. TAKEDA. for. their. cordial. OKUTANI. Mikawa-Issbiki,. National. studied. National. under. University T.. in. reported.. Yokohama. shell-bearlng. extended. Yokohama. not. paleoenvironment. writers. S. HAYASHI. (1973). paleoecologlCal. thanks. CEINZEI. i.. Setouchi. Morozaki. hearty. University,. were. molluscan. fossil. StIIBATA HAYASHl. assemblages,. thesis. the. present. such. structures. Miocene. Miocene. interesting. Table. SHIBATA. molluscan Group. Series,. &. sedimentary. &. Morozaki. authors,. ITOIGAWA. of the. graduation. several. in. the. the. on. describe. Of the Setouchi. shown. correlations. based. many. and. Assist.. Research and. collected. molluscan. Miocene. by. ITOIGAWA. and. fauna. of this. purpose. of the molluscan Morozaki Group Here. a. the. on. sequeIICe. (1955), and. and. molluscan. TAKEDA. the. studied. changes Group,. paleoenvironmental the Morozaki including of. to. was. ･area. (1970). SHIBATA. the. details. thick. a. belong. HAYASHI. (1929),. part. Among. discussed.. are. were of their research & IwAI (1959) studied. HAYASHI. Recently,. to. southern. paleoecology.. Based. called. acknowledgments. Peninsula,. of this. geology. results. and. and. considered. (1925), OzE. NAKAMURA. as. been. fauna. present. Cbita. of. part. viewpoint. is here. which. in the. of. distinguished.. Introduction ln the. Group,. developed. that. the. are. pelecypods. characteristics. Morozaki. of. Tokyo,. thanks. his to. Assist.. Regional Of Tokai Aichi Pref., and. University,. for. their. dif-.

(2) 2. SHIKAMA. T.. ferent. of help. kinds. and. Tbe. Morozaki. is. composed formablly. thick. of. in. Formations A. breaf. bearlngS. in. into. the. part. southern. Ryoke. this. of. study.. Chita. of. The. sediments.. the. :. course. Group Peninsula lies. group. Metamorphic. uncon-. is. Complex.and. The Morozaki unconformity･ Morozaki, Yamami, Utsumi and. Group. formations. the. the班orozaki. marine of. rocks. four. ascending. the. of. Tokoname. vith Himaka,. order.. description. Of. distributed sequences. Pliocene. the. is divided. Group. of. foundation. the. on. by. overlain. Group. outline. EASE. during. glVen. suggestions. Geological. T.. and. of. formation. each. and. paleontologlCal. follows,. paleoecologlCal. on. study. intimate. have. they. since. the. vhich. present. is based.. work. 1.. Table. Stratigraphic. NAKAHURA. terminology. 工TO=GAWA&. HAYASBI. OZE. Morozaki. the. of. Group.. TAKEDA. herein. SH=BATA. (】925). (】929). EARLY pLE工STOCENE DEPOSITS. (】955) PL工OCENE&. TOKONAL4B. TOEONAAIE. QUATERNARY. GROUP. (】976). (】975′MS). (】973). TOKONA凹E GROUP. GROUP. DEPOS工TS. UTSU出=. UTSU出Z. h. UTSUM工. H. 凹EllBER. UTSUI4=. ま tIAJ=KAJ4工. EAJ=KA>1I. FORMAT工ON Pl 〇. く⊃. ⊂) E< U. FORhAT=ON. RU出UR且. FOFu4AT工ON. 良. TOG=YA. H. IIE凹BER. YA♪1且虹工. =). D ○ P;. く⊃ p弓 ⊂). N. ○. 萱. =WAYA. A: >1. かIEMBER. 出E凹BER. )1E♪1BER. FORMATION 凹OROZAK= 凹EZPJBER. llIMAKA. FORI4ATION. E工上4AKA. FOfu4AT工ON. Himaka. east. Formation. Morozaki,. of. formation. ture. slid. in. Shino. observed from southeast. tact. between. and. the. the. COhlPLEX. to. of. the. small. Ryoke. of. siltstone. of. to. medium-. thick. are. Ryokeb､Metamorphic around. Metamorphic. coarse-grained. formation Complex,. it, with. Complex. unconformity. and. that. the. is. the to. struc-. sandstone lie. on. the in. distributed. However, Himaka. of. nearly. Slump. is thought which. beds. attainlng. lamination.. well-developed Higashihama, indicating. 2.5. about. Hazu-misaki.. intercalating. thick. with. beds. sandstone. situated. the㌧cape. at. have. nわrthwest. ･ This island. lsland,. distribution. small. gray. and coast. Himaka. on. alternation. general,. thickness at. rock. dark. In. a an. of. and. tuff.. maximiim. island. has. and. sandstone. is. foundation. is developed. is composed. light-colored丘ne m. I ET且凹ORPH=C. Formation. tuffaceous. 5. RYOEE. 凹ETA出ORPE工C. GRANITE. CO凹PLEX. Himaka. This. FORD4ATION. RYOKE GNE=SS. GNEISS. The. E=MAR且. FOR凹AT工ON. GRANITE. km. f40ROZ且K=. ⊂) 仁E: ⊂) ≡. OSA. Pく. ○. 1iZ凹且KA. HZ凹且KA. 〉く r< N. TOYOIiA11且. 冒. FOR凹且T=ON. FOR♪lATZON. ○. FORMATION. STAGE. Y且凹且凹=. H. F.ORIl且TZON. FOR岨ÅTION. E=凹AモこA. O; U. i< r< ら N ⊂) pく HH a F< N. TOYOHAか1A. ○ Di ○ E:. f40ROZAK=. ≡: STAGE. =). =. 巨石 <. TOYO壬Ⅰ且ト1A FOR♪1且T=ON. 出OROZAK=. DJ. ”. H. E< ■く N 凹OROZAK‡. 凹EP′iBER. PJ. FOR凹AT=ON. H. FORP4ATION. NAKIRI. E+. P< =) P; U. STAGE. こ) U). FORト1AT=ON. no. con-. Formation.

(3) Fauna. Molluscan. be. can. The. observed.. Himaka. Miocene. the. of. is. Formation. Morozaki. Group. measured. more. 3. 200m. than. in. thickness. Fossils. are. Dentalium. and. of the Formation. Morozaki Tbis. sandstone. about Three thick. formably.. lower. The and. mudstone.. the. top,. The. Foss五Is. are. Portlandia. in. common. Lucinoma. and. At. parts.. lower. the. tipper. part,. Part. this. of. dark. of. towards. this formation. Of. shale. gray. increases. again.. Acila. chitanii,. (Truncacila) pL'ctulata, Portlandia (Portlandella). but. rare. as. such. Calyptogena. etc., acutilineatum, (Loc. M5), Callianasa. Osa. part. tufflayer. and. horizon formation･. are. in. the. occurs. chitaensis. middle. and in. abundantly. nodules.. ･round. Yamami. Formation. Yamami. The Morozaki. Formation. Formation. coarse-grained. is. into. with divisible. has. along. sorted,. poorly. the. and. diameter,. ･maximum. Metamorphic The. intercalated. The. Utsumi. base. marker. siltstone Thick. angular. lamination.. part. this. of. to to. sandstone,. The. subangular. is. distributed. are. cobble-sized. This. formation. and丘ne-grained Yamami.. the. on. formation. parallel. conglomerates of. vest. pebble-. This. thick｡. m. lies. and. conglomerates. Ryoke. the. of. gneiss. in. 3m. to. up. and. monzonite, containing granodiorite, and seris composed of siltsone occasionally of this formation. beds. sandstone. are Portlandia. (Hatai-. besshoense,. (Aelga). etc.. Formation. Formation, in. distributed. widely. of. lower. Tbe. of tufEaceousfine-grained The main constituents abundantly. Yoldia (s.s.) sagittaria, and Periploma. occur. Utsumi. part. thin. tokunagai,. yldia). is. with. area. ; sometimes. upper. with. Fossils. lithology.. gravel. consisting. Complex. pentinite.. in. parts. sandstone. of dark gray alternation interbeds tufflayer. o-i the coast of Tsubutegaura,. some. locally. two. 140. about. measurlng. tufEaceous. Yamami. the. ln. widely. an. of. ･composed. occurs. conformably. begins. measuring. parts.. 五ne-grained. uppermost. western. about. lower. sandstone,. in. and. measures. either. This. thickness.. consists. of which. of. the. about. Morozaki. Group,. is clearly. defined. ￣i白噛6Iltraceable. sandstone,. 4m. part. part. of thisfield, and. p?rt. coarse-grained. conformably. The. the. the. of massive. Formation two. the. upper. con-. remarkable. predominantly. sandstone. in. decreases. (Hataiyoldia) tokunagai,. vcf. wataseL,. the. of the. amount. latter. the. consists. Formation. Himaka. formlng. and. middle,. consists. and. with thin interbeds Formation Morozaki. The. the. sandstones,. coarse-grained. area. mudstone. overlies. (s.s.)divaricata,. the. Morozaki. fine tuff.. and. of this formation. part. but. thickness. coarse-grained at the basal,. developed. are. markers,. in. m. in. abundantly Island.. light-colored. and. 420. is measured. are. coast. sp., Acila. in the is widely distributed of dark gray shale and tuffaceous. ･offine-grained. and. occur Which Himaka of. etC.,. west. Macoma. except. formation. predominantly. upper. formation. yokoyamaL,. bed. sandstone. in this. rare. which formation. 70m. of a･rhythmic increases. lies. thick. alternation in thickness. on. It is. the. as. is. by key. a. Yamami. divisible. into. of siltstone. an-d. the. top.. towards.

(4) T.. S王-IIKAMA. T.. and. EASE. Columer Formation. fossils. characteristic. section. TOKONAMEGROUP. por七Landia(Hataiyo乙dia)toたunagai. ⊂). FORMATION. tー. YAMAMI. EL =) ⊂) 【ヒく.ウ. .!j.'｡.'よ･｡･｡･'･..･. ∈. UTSUMI. pot,t乙andia(Hataiyo乙d7,a)tokunagaも. ∈. L･YLia8aii;tapia Yo7,aOg. ⊂). pepipLoma(AeLga)besBhoen8e. てr. FORMATION. Yヽ′ヽ′ヽ′V. ｢･+. Lin士hianipDOniea yマJ｢′■■∇gJ｢′. ゝ亡. ...<･･･.. ヱヱV_ViYヱV. ≡. < N. cazliana8aChitaensis. l′l′ヽ′1′Vヽ′Vy. ⊂). 0 ■【ヒ ⊂). 1よL>+亡V_V_VV. ∩ 勺1. FORMATION. AciLa(Tr,uneaciLa)piei;uLai;a pot,七Landia(Hatai_yoLdia)i;oたu7Wgat･. .1'ミ..こ一こユ'ii-.Lil. I,｢Fy-yて㌻y-v-. ≡. ⊂)＋. AciLa(Aci乙a)divapiea七a. 完∈. FORMATION. ■′ヽ′Yヽ′＼′■■ヽ′ヽ′. Deni=aLiw71yOたoyamai. 工＋＋＋＋＋＋. RYOKEMETAMORPHIC COMPLEX. ○. Fig.. Stratigraphic. 1.. 4:. mudstone,. The. upper. 2:. Conglomerate,. sandy. the above-mentioned This formation. ween. (Hataiyoldia). portlandia Tokoname The. T･okoname. Group. containlng. and. sandstone. beds. thick,. developed amounts. bet-. of. fossils,. molluscan. is occasionally. of血e-grained. are. COnSiderable. distinct. no. wide gravel,. mud,. Group. plant. although. occurred･ in. area. Chita. the. tuff beds･. and. and. clino-unconformlty Morozaki of the. with horizons. lower. the. with. a. occupies sand,. unconsolidated Morozaki Miocene. contact. chita. Group.. comprises the. of. intercalary. carries. tokunagai. of. gneiss･. with thin 3 to 4m beds,. units,. fragments.. part. southern. alternation. 6:. tuff,. sandstone two. the. 田6. 5. Prefecture. 3:. 5:. siltstone. Coarse-grained. sandstone.. Aicbi. sandstone,. mudstone,. is of. part. in. sequence. Peninsula, :. 畠4. 3. 2. ○. O. o. Maeoma8P･. ヽ■ヽ■ヽ′ヽ′ヽ′ヽlヽ′. HIMAKA. 1. pot,七Landia(HataiyoLdia)toたunagai. v_v-v_v-i7_y￣セ.). MOROZAKI. ■･-■. Group. Peninsula,. This. and covers. group. in. comes gradually from northwest. to. southeast.. As. the. the. of. study Group. present of the Morozaki Miocene. is here. the. junior. mode. of which are in the. and paleontologlCal dscrlption Group'detailed of. Of. a甲eCtS writer. found in. occurrence. of 1. paleoecologlCal Tokoname. the. omitted･. General The. is. work. scope. (Loc. M1) Morozaki. is. in. localities. fossil. and. fossils from molluscan There his負eld work. the. Formation,. Himaka and. Formation, 4. (Locs.. Yl,. mode. of. occurrence. 27 localities were. investigated. and. 9 noteworthy. 6. (Locs.. Y3,. Y4,. Ml,. Y9). localities, M2,. are. M5,. M10). in the. Ya-.

(5) N LEGEND. 0 0. 千. 0 0. 0. NO仙A 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. o O. 0. 0. 0 0. 0. 0. 招. YA仙仙FOR肌ATJON. E3. J^OROZAKf. 0 0. 0. 0. O. 0. o. 0. 0. O. 0. 0. 0. .0. 0. 0. 0. 0. ヾ. 0. 0. 0. O. 0. 0. 0. GROUP. UTSU仙FO帥ATJON. 0. 0. ㌔. TOKON仙E. 0. 0. A. Ej. O. 0. 0. o. O. 0. 0. 0. 0. 0. O 0 O. E3. o. 0. 0. 0. 0. H似AKA. FOR仰ON. 0 o. 0. FOR仙ÅT10N. o. 0. BJ. 0. 既. 0 0. 0 0 0. 0. 0. GNEJSS. 0. 0 0 0. O. O. 0. 0. 0. O. 0. 納IKAwA. 0. 0. O. 0. 0. 0. 0. 0. 0. 0. O. 0. i>. 0. 0 0 0. uTSUA^l. I. 0. 0. 0. 0. .. 0. 0. 0.. 0. 0. 0 0. A. 0. 0 0 0. 0. 0. 0 ヽ 0. / 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0 0. ′●. 『. 9 0. ■. 0. 0. 0. P )A. 郡. 10. r>. ○. ヌ他8. <'. .犬川9. も夕. ヽ. ＼1. 3. ㌔. ･13{ RIMKA-JIAl^. ㌔ A. ⑳. ”_I.'‡■∴`∴●∴●∴●∴●∴一∴●.'. 也. a. ＋. 8. SH削OrJlぬA. B′. Fig.. 2.. Geological. map. of. the. southern. part. of. Chita. Peninsula.. 十.

(6) Molluscan. Formation.. mami. composition. of. 200m. of mode. 5. and. faunal. Island,. Mina-. occurrence. of. of Nishihama,. south. alternation. of. dark. gray. thicker. than. and and. Group. cited.. are. an. laminations. tuffaceotlS. general,. descriptions. about. composed. parallel. in. each Seacoast. Morozaki. Miocene. the. of. brief. locality. Hl;. micbita-cho, with. Here,. at. Loc.. Fauna. Himaka. medium-. to. sandy. coarse-grained sandstone The are, siltstone. sandstones. siltstones,. a. attaining. of. maximum. 5m.. about. Abundant. sagLttarla, deformations,. but. horizon. in. fossil. molluscs fossils. these. places. Naticidae. in. some. (s. s.). secondary. a. restricted. habitats. of these Therefore,. Species.. transported. were. and. for in. benthic. the except. orlgln,. Yoldia. scattered. valves. bottoms,. mud. allochthonous. 50cm. indet.,. sp.. in. from. remote. bed,. sandstone. and. Soshinji. of. sand-. Dentalium. siltstone.. indet., etc.,. sp.. et. gen. their. WNW. ill-sorted血e-grained. tufEaceous. Trochidae. and. 140m. cliff, about Varicolored. is interbedded. thick. et. gen.. roadeside. Mina皿ichita-cho.. above-mentioned. poor. sandy. Three-forked. about. the. are. except. Furthermore,. associated. yokoyamai,. is good. fossils. species. death.. Morozaki,. stone. to. mud. dominant. (Hataiyoldia). detached. are. laminae.. with. are. Ml;. Temple,. fossils. most. bed;. sandstone Dentalium. tokunagai,. these. of. preservation. parallel. after. Loc.. Portlandia. praenipponica, The. etC.. a. and. s.). Ennucula. with. in. fossils occur molluscan Acila diuaricata, sp. (s.. Macoma. are. occurrences. sp.,. in. occurred. sporadic. are. with. preservation. Loc.. M2:. Large Gray. michita-cho. and. pumice. (Truncacila) (Acalax). Pictulata to. occur. bedding. the. Other. this locality. of. with. conjoined. valves.. Roadside. cliff. are. beds.. Most. etc. some. Mina-. sandstone. Dominant. species. to. they. them. of. run. have. some. almost. been. vertical in situ.. entombed but. extent,. may. associated u)atasei, Lucinoma Acila (Truncacila). the. of. may. species. arranged. Thus,. of血e-grained. (Hataiyoldia) (Portlandella) cf.. and. this. Katana,. of. tokunagai,. chitanii, valves,. south. mudstone. Portlandia. Therefore,. plane.. species. occur. conjoined. with. in the. Portlandia. tokunagai,. Calyptogena. and. acutilineatum,. many. occur. pL'ctulata,. 500m about interbeds. Valley,. with. fossils. Solemya. with. a. ln. mudstone. Many. tuff.. Acila. are. quarry. most. an. represent. of. them. autochthonous. assemblage.. Loc･ School,. M5:. Minamichita-cbo･. is exposed･. in the. Callianasa. Loc･. (s. s.) inermis,. cho･. Well. M10. :. Seacoast. 1aminated Shells. mudstone･ Palliolum and sandstones･. occur. 1 km. about. in calcareous. west. round. nodules. preserved. (Hataiyoldia) toku7?agaiand. are. almost. of Matsubara,. sandstones. Acesta. shells. sandstone. with丘ne-grained. Portlandia. (s. s.) goliath, were (Delectopecten) peckhami. These. Primary. occasionally.. fine-grained of. Toyohama. of. northwest siltstone. chL'taensis occurs fossils, such as. Other. siltstone･. Malletia. 250m. about. Light-colored. buried. Portlandia taken. with. Yamami,. Minamichita-. interbedded. are. in ■ dark. gray tbkunagai, (Hataiyoldia). from detached. the. above-mentioned. valves. and. arranged.

(7) T.. Table. SHIKAMA. T.. and. EASE. 2.. Locality. ＼. ---. __. Fossil. H2. HI. ＼. MIM2. M3M4M5M6M7M8. PELECYPODA Solemya. (Acarax). Nuculana. Pennula. Ennucula. praeniPPonica. Ennucula. sp.. Acila. 3. (YoKOYAMA). tokunagai. (YoKOYAMA) 9. KAMADA. l 13. (HINDS). divaricata. (s. s.). -. (YoKOYAMA) (Truncaci'la) pictulata Malleiia (s.s.) inermis (YoKOYAMA) Acila. Malletia. (Minormalletia) (YoKOYAMA). Bathymalletia. Neilo. chitensis. poronaica. nov.. sp,. morozakiensis. Neilonella. isensis. Portlandia. (Hataiyoldia). YoKOYAMA. Portlandia. nov･. sp.. SIIIBATA 5. tokunagai. (Portlandella). cf･. -. --. u)atasei. ∼-. (KANEHARA) Yoldia. (s.s.) sagittaria. Glycymeris. vestitoides. ProPeamussium Palliolum Pinna?. 5. YoKOYAMA. 1. NoMURA. 23. -. -､. -. 10. 1. 1. 3. --. (s.s.) tateiwai KANE上1ARA (DelectoPecten) Peckhami (GABB). sp.. 1. 5. 1. -. Acesta. (s.s.) goliath (SowERBY) Venericardia (Cyclocardia) cf･ siogamensis (NoMURA) Venericardia. (Cyclocardia). cf･. 5. 1. tokunagai. YoKOYAMA Lucinoma. Calyptogena. 1. (CoNRAD). acutilineatum. (KANEfIARA). chitanii. 〟αc∂∽α sp. besshoense. (Aelga). Periploma. 1. -38. 1. -. -. -. 15 18. -. (YoKOYAMA). 2. --. SCAPⅡOPODA Dentalium. yokoyamai. Dentalium. sp.. 34. MAKIYAMA. --. GASTROPODA Trocbidae. gen. sp.. Naticidae. gen.. 3. indet.. et.. sp.. indet.. 1. -. 13. 3. 1. sp.. Makiyamaia Turridae. sp.. 1. Turritella. Fulgoraria?. et. coreanica gen.. et.. sp.. (ADAMS. and. REEVE). indet.. ECⅡINODERMATA Linthia. .. niPPonica. YosI寸IWARA. CRUSTACEA. Callianasa. chitaensis. NAGAO. -. -. 34. -. -. -.

(8) Fauna. Molluscan. Morozaki. Miocene. the. of. Group. Bathymetric. M9. MIOl. Y2Y3. yI. UI. Y7Y8Y9YIOYllY12Y13. Y4Y5Y6. U2. U3. range. 100-500. In. (20-1000 m). (0-1460 孤) (0-1460 m) 0-500. m. (0-870 m) 1. -. (｢. 2. (-) (50-200 m). 2. -. (100-600 m). 2. 2. 2. 15. ). --- ---. 18. 13100＋. 7. 1 43. ---. 20. 3. 6. 1. '1. -. (50-1300 m) (20-1400 m). (20-1400 m) 4. 2. 2. 3. (20-250 m) (5-300 m). 1. (20-300 m). -. (100-500 m) 100-1395. 7. m. (10-400 m) (10-400 m). 1 19. (10-750 m) (100-750 m). 1. -. -. 2. 7. -. -. -. 10. 3. -. 2. 1. (0-1030 m) (100-1220 孤). -. 100-200. m. (-i) (-) 2 4. 1. (o-300'm). -. (-). 1. -. 100-250. (-) 12. ･一丁. 2. 一. 丁. 1. 2. -. -. -. -. -. --. -. m.

(9) 8. T.. to. parallel Loc･. Y､1. Massive. part. Molluscs. gray. shoense. is. joined. valves. Yamami. slightly. main. constituent. entombed. fossils. show. 1 km. about. south. dark-colored. life position.. orlglnal. Yoldia. tokunagai,. toward. (s. s.). to. the. Periploma. show. con_. It is considered Por_. are. constituents. sagittaria,. bes_. (Aelga). plane.. Other. the. northwest.. of them. most. and bedding. the. Minamichita-cho. corresponds. Inclined. locality, to. parallel. Okkata,. of. sandstone. siltstone.. of this. almost the. (Hataiyoldia). tlandia. EASE. with血e-grained Formation gently. from. the. these. quarry. siltstone. the. of. occur. T.. and. plane.. Roadeside. :. light. lowest. that. bedding. the. SIIIKAMA. Propeamussium. and. (s. s.) tateiu)ai. Loc･. Y3. ple, Iwaya,. 5. about in the than. Tributary. :. thick. cm. half. bed,. are. These. few,. are. which. Associated. oblique. species in. hurried Loc･. Y4:. in. These. species associated. Nuculana. and for. some. pennula, and have. Kono,. Minamichita-cho･. thick. Portlandia are. Formation. 20. Temple, 30cm. to. fossils. thick丘ne_. sandstones and. vary. Yoldia. and. besshoense. near. to. detached Pro-. and the. bedding. places.. 200m. about siltstone. and. with. parallel. from. Iwaya,. Pro♪eamussium. occur. (Aelga). almost. Massive. tokurtagai. besshoense,. with. west. Ten-. of. interbeds. many. In the exposed. Neilonella isensis occur, are. and the. lies. faunal. Morozaki. siltstone no. and. on. the. Ryoke. characteristics Grotlp Metamorphic. Complex. an. conformity. and consists of alternation of sandstone is dominant. It the Sandstone that considered sandstone current because turbidity in having mostly orlgin graded poraneous. have. may. associated.. of Himaka. These. Dodoboike. at. medium-grained. (Hataiyoldia). (Aelga). transported. cutting. Paleoenvironment. The. of Tenryuji. arranged. been. ryuji Temple,. o′ther molluscs. size. besshoense,. assemblage. intercalates. Periploma. of. are. roadside. of about. northeast. a. in. vary. (Aelga). This. etc.. specimens. Small. bedi. Periploma. for. except. but. general. chitanii.. Periploma. with. Y5:. 20cm. plane,. sporadically masive siltstone Portlandia (Hataiyoldia) tokunagai. are. may. Loc.. in. More. (Hataiyoldia). in. fossils. plane.. the. inermis,. siltstone. occur. (s. s･) tateiwai,. Peamussium. bedding. small. 350m. gray. Fossils. Dominant. except. valves. are. (s. s.). cliff about. Massive. (s･ s.)sagittaria, (s. s.) tateiwai,. They. Calyptogena. and. Roadside. sandstones･. size･. it･. Portlandia. are. richly. thick.. situ.. Minamicbita-cho. grained. them to. occur. 30cm. about. interbeds. which. Molluscs. horizon. of. subparallel. Malletia. are. most. thick,. m. Tem-. of lwayaji. southeast. 5. matter･. restricted. and. occur. to. a. m. about. carbonaceous. in. valves,. fossils. (s･ s･) sagittaria,. Yoldia. with. especially. conjoined. tokunagai･. been. sandstones. siltstone. 300. roadeside cli庁about Massive siltstone. Minamichita-cho･. conglomerates,. and. slump. structure. as. in. un-. with. and. siltstone,. with. of this. formation. are. bedding, the. case. penecontem-. of the. other.

(10) Fauna. Molluscan. formations been. the. at. tions. are. the. transgressive remarkable. buted. area. facies. The. in. shoⅥ1. to. tical the. maximum same. living. the. fossil. the. the. upper. The-. stlbsided. area. present. regresI. slightly Formation･. Yamami. the. south-. alternation. rhythmic. indicates. and. and. minimum. genus. or. gradnally. Yamami. the. of. part. 2, and. in. in. parentheses,. from. various. each. of. several. species. is. assumed. recent. represen-. because. are. they. iden-. are. which bathymetric. The. (1973)･. are. ranges. species. of the. fossils. other. bathymetric. distribution. except. HIGO. on. and. molluscan the. habitat. of. Subgenus,. shown. are. species. Table. depth. based. species,. Of. occurrences. in. depth. The. table.. same. in the. tatives. a. shows. in the. seen. was. the. toward. abruptly. out. distri-. are. deposited.. was. the. the. -from. Ryoke. swell. steep. of. part. of lithology, viewpoint transgression when maximum. geologlC and quantitative are Group Morozaki shown. the. of. upper. the. and. reached Formation. a. of the Yamami Metamorphic. part. conglomerates. thin. and. structure,. slump. the. These. most. Tsubutegatlra,. of. the. of. Formation. Utsumi. with. with. compared. from. refore,. sandstone. and. siltstone. The. coast. middle. gravels. the. shows. and. the. the. diameter･. maximum. time.. that. at. of. coast above-mentioned to indicate that facts seem. These. north.. composed. in. At in. the. at. Forma-. Yamami. and. beds. Group.. developed. are. 3m. intercalary. without Morozaki. almost. to. up. only. sive. are. and. Morozaki. stru-. slump. The amounts and sandstone･ of siltstone alternation howYamami Formation, The small. upper part of the. conglomerates. _Formation complex,. in the. observed. as. have. may. an. of siltstone facies in the. consists. of. are. sandstone. ever,. .ern. of. composed. 9. Group. of this formation. sandstone. the. coast. east. The. Group･. Morozaki. direction southeast The lsland･ of Himaka. from. transported. ､cture. of. Morozaki. of the. Miocene. the. of. of. ranges knoⅥ1. not. pre-. LCisely. As. to. tbonous Loc.. fossils. the. Hl,. nearly. autochthonous it is. M10,. Ml,. (Hataiyoldia). portlandia 血ence. be. it may. the. regarded. compositions. speci丘c. The. horizons･. ,geologlCal Macoma .｡f yokoyamaL, thonous chitanii. in. etC･. origin. occur. at. lower. occurr?nce. the. ilandia. the. autoch-. show. few. a. localities. as. such. based. paleoenvironment. Also, Loc.. H2. part. the. of. of Acila. (Portlandella). of. the. on. Praenipponica,. (Portlandella) formation,. but. fossils. (Loc･ M2). Formation. and. inermis,. Solemya. in. different. the. Dentalium. indicate. alloch-. Calyptogena. occurrence･. is characterized are. constituents tokunagai. associated. Calyptogena. (Acalax). occurrence. and. and in. rare. (Truncacila) Pictulata･ Main Portlandia (Hataiyoldia) and. cf. watasei,. may. watasei. cf･ very. Group,. by. is characterized. these. geologically･. Morozaki. different. are. species. Ennucula. (s. s.). of the. element. However,. Morozaki. distributed. widely. representative. this. Malletial. acutilineatum,. is most. of the associated Formation Himaka. sandstone･ Portlandia. (Truncacila) Pictulata Lucinoma. as. tokunagai. (s. s.) diuaricata,. Acila. sp.,. .The the. this丘eld. except. deduce. to. possible. in. localities. occurrences. assemblages･. outcrop. but. collected. tokunagai,. chitanii, etc･. by. Acila with. PorThe.

(11) 10. T.. bathymetric. range. dicates. about. exactly. with. species. is small,. and. however,. auied. genric. fauna. in. & The. these. are. Neilonella. thymetric. ranges. the. Utsumi. of. as. 1uscan. Also. area. where. south deep,. are. is. very. or. an. Cape. of. a. akoya. Hopshu,. it may. them. be. with. UDA in. area. and. stated. cape. Shionomisaki･. low. salinity. and. ln. the that. a. bottom. and. Bathymalletia. a. This. gastropods slope. lying. is, turbid. and. the. of. of. determine mol-. area. cold. than. 1939. to water. is characterized relatively. rich. by in. bathyal. special. batbyal. Puncturella. akoya. IKEBE,. &. Also. HABE.. (REDFIELD). regia-Calliostoma the. of. off West. waters. is located. water. (RiPhane-. condition. south. nutrient. Acesta. the. oregonensis. (A) low. (HABE),. of. KuRODA. in the. mass. few Mal-. as. Puncturella. the. a. rare.. north is another. hydrographical. the. bathyal. a. Allogramma. just. there. Aichi. where. extremely. are living such elements Calliostoma (Akoya). reported from 1934. mass. in. living. OyAMA,. HABE,. peculiar. shown. number to. 甲ater cold inaequilateralis. are. (1940) years. the. particular. rubrotinctum. Prefecture,. Shallower. 100. fossils. di氏cult. a. about is. As. ba_. (Fig. 3). depth. at. localities.. small,. Glyptamussium. &. as. molluscs.. as. bathyal. assemblage.. Kuroshio. few. a. muddy. with living such. SHIKAMA. Formation. Molluscan. -. assemblage. in. The. etc.. in Mikava-Isshiki, conchologist active Da主o-zaki, Mie Prefecture, there is. an. HABE,. is living. (Hataiyoldia). of pelecypods Bay.. Yoldia (WATSON), (s.s.) similis and Fusitriton (Niueotectura) pallL'da (GouLD). Acmaea. fossil. fossil molluscs. of inhabitants. Sagami. compare. fossil. on. Oyashio-type. rolepida. in. poor. tateiu,ai,. Yamami. the. composition in. Wakayama. regia. are. the. (s. s.). of. in. found. off Uragami,. transenna. to. KuRODA,. and. Portlandia. of. ranges. composed. zone. range. 600m. mularax). 200. or. s.). carinifera (Bentholyonsia) sp･, Periploma(?) sp. ; in the continental smithi (Sow･) is found area･. (100. present. is characterized by the abundant Yoldia tokunagai, (s. s.) sagittaria, and pennula, Malletia (s. with Nuculana. subgeneric. individuals. in the. special molluscs letia (Neilo). are. S･ Hayashi,. to. Formation. occurrence. molluscs. been. based. According. about. the. of. zone. (1962, 1968),. Propeamussium. and. or. have. assemblage. area,. of Bay,. and. rich. associated. arcbibenthal. well batbymetric. Prefecture,. quite. fossil. generic the. the. (Hataiyoldia). the. as. exact. is. assemblages. Formation. species. number. of inhabited the assemblages in depth about 100 to 200m Morozaki Formation. The part of the fossil occurreece. isensis,. the. bottom. the. bathymetric. of. Also,. 250m･. pelecypods. Morozaki. of the. the. shows. besshoense,. (Aelga). inermis,. that. 3 in-. Sagami. In. arcbibebthal. Fig･. assemblage. the. peculiar･. OKUTANI. 3. Portlandia. of. shows. of. (1957),. parts. of the Yamami Formation. Periploma. the. characterized. lower. case. the. bottom. this. because. compositior”f. by. indicating. occurrence. to. upper. Figure. units. in the. is. in. shown. compare. assemblage,. compo如ion. HoRIKOSHI. and. but. tokunagaL･. subgeneric. to. (1971).. middle. occurrence,. or. muddy. to. OyAMA. speci丘c. is. which. It is difBcult. molluscan. the. the. according. HABE. assemblage,. depth･. living. particular. EASE. T.. and. present in. 300m. to. is found. lOOOm). in. 100 a. the. of. SHIKAMA. south. off. temperature salts.. and. It is rich. in.

(12) Fauna. Molluscan. dissolved This. m.. in. deep. unique. Morozaki. the. Oyasbio. a. similar. be. by. to. able. may be. may. The. by. live.. These. have. lived. located. in. few. a. this. paper,. Fauna. species. for. in. unlque. tO. a. is. eXist･ Fauna the. as. Such. ecosystem,. inland. a. such. this. peculiar. fauna.. type. generally. the. based. on. of assemblage Portlandia-Linthia assemblage molluscan. of. assemblage. (1970), and (1973) judging. SHIBATA. IGAWA. &. and. specific. (1960) is. lTOIGAWA. characterized Pennula, Portlandia. Nuculana. minoensis,. and. Oidawara. closely. related. semblage,. Linthia. to. member. which by Acila. that. of. the. is de血ed. Fauna,. Group. watasei,. (cyclocardia) is. siogamensis, Loc･ at typlCal. by. and K35,. sp･. except. indet･. is. a. have. shallow. distinguished. and. speci丘c. In. tokunagai. (1973). which. many. composition･ to. correspond. roughly. Neilonella-Palliolum. assemblage. of. ITO-. the. etc･,. of the Morozaki SHIBATA. sp･,. mudstone, which Mizunami Group. Group･. The. (1970). many. K73,. pelecypods. K76,. and. in. sp･, Thyasira. ProPeamussium. in. (s. s.) divaricata, Neilonella Propeamussium (s. s.) tateiwai, Acesta. cterized. et. SHIBATA. and. may. abundant. (1960), the Neilonella-PeriPloma. ITOIGAWA. (Megayoldia). n軸om'ca,. mudstone. above･. of enclosed sediments combination The Portlandia-Linthia fossils･ of assemblage Solemya by Portlandia (Hataiyoldia) tokunagai,. of. compositions. cited. (Hataiyoldia). Series,. sediments. from. present. by. gene. Setouchi. Morozaki. the. the as. may. Morozaki. gastropods,. &. enclosed. of. S甘IBATA. and. ITOIGAWA. Kadonosawa. the. fewer. Portlandia. First. sea. Characterized. Naticidae. and. name. the. of. lS. tokunagai sp･. personal. depression. faunae. Group. (1970), and. called. aasemblages. molluscan. to a. of the. because inland. Paleo-Seto. Morozaki. fauna. molluscan. offAkita. gastropods. fauna. molluscan. wi仙ot血er. Turritella. propose. as. animals. environment,. (Hataiyoldia) as. the. that. of the. the. of. active. stagnant. depression. a. (1960), SHIBATA. sea. depression. trough-like. a. and. suggest. such. writers. the. studied. in. water,. facts. the. ITOIGAWA. blage. in. in. there. and. no. stagnant. Portlandia. of. for. the. area,. found, are according gastropods Y･ Iwasaki･ Perhaps K･ Chinzei and such. fauna. molluscan. occurrences. sp.,. Kuroshio. may. enclosed. ecosystem. found. Comparison. the. are. area. fauna. a. is. almost. Drs･. dominated. Group. The. Under-. Shionomisaki. elements. the. 50. below. Oyashio. the. cape. of. layer. alloⅦ-ing unlque Portlandia (HataiyoldL'a)tokunagai. the. represents. assemblage but. communications. area. suggest. Group. pelecypods. where. not. that. in. by. caused. Oyashio. of. deeper. Undercurrent･. AIso,. may. assemblage. molluscan. to. seem. be south. assemblages Undercurrent Oyashio of mass in the special. water. enclosed facts. regarded. ll. Group. in the. poor to. bathyal. sea. These of. the. which. There,. belong.. is. mass. but. layer,. surface. water. cold. current. an. in the. oxygen. Morozaki. Miocene. the. of. the. isensis,. are. This. found. is. assemblage. Neilonella-Periploma lcbishi. Group,. Portlandia. (s･ s･) yagenensis,. in. only. as-. is chara-. (Portlandella) Venericardia. This and gastropods･ K82 in the Kamimitsugano. assem-. facies.

(13) 12. T.. SHIKAMA. T.. and. EASE. 17 16 15 14 13. A. ll 9. 8 4. Om. lOOm200m. 500m. 17. 13 12. a. ll. 8 4. Om. lOOm200m. 500m. 18 16 15 ll 10. C. 8 7 6 5. 3 2. Om. 一oom. 200m. 500m Deplh. Fig･. the. 3･. Bathymetric. Morozaki. MT3110,. Formation 2:. tokunagai, Pictulata, Portlandia Yoldia. 5:. C:. 13. :. ll. Venericardia chitanii,. coreanica.. :. upper. Formation 3:. chitensis, tokunagai,. (Hataiyoldia). Calyptogena. Makiyamaia. pennula,. Bathymalletia･. molluscan. B:. the Yamami. Nuculana. (s･s･)sagittaria,. Peckhami, 15:. M9),. except. of. M2),. the. ranges. (Loc･. Enncula 6. :. 9:. (Cyclocardia) Periploma. Morozaki. (Loc･ YトY13)･ 7. 1. :. Solemya Acila. Neilonella. morozakiensis, Portlandia (Portlandella). (s･s･) tateiwai, cf･. tokudagai,. (Aelga). 12. 14. besshoense,. : :. :. part. of. Formation. 4:. praeniPPonica,. Neilo. Propeamussium 16:. of the. lower. A:. assemblages･ part. cf.. Palliolum. Lubinoma 17:. (Loc. (Acha,ax) (Truncacila) isensis, watasei,. 8. :. 10:. (DelectoI･ecten). acutilineatum, 18: Turritella sp,.

(14) Fauna. Molluscan. Oi. the. of. Formation Formation,. Katada has. many. in. the. latter in. gastropods,. and. rare. noteworthy. that. the. to. all horizon.. be. located. the. Furthermore,. Morozaki. to. a. the. Neilonella-PeriPloma. speci丘c. between. however, consistent,. and. Morozaki. in. seen. in. be. fauna. kinds. inland. the. from. each. other･. The. bathymetry; is very. zone. archibentbal. molluscan. of. each. fauna. sur-. bay･. remarkable Group and. differ. different. to. is. of. Morozaki. near. sea,. area. It is. Group. the. of. inland. mouth. south･ the. due. is. in the. as. thought. (Hataiyoldia). Takinoue. of. Ichishi. tokunagai. show. the. of Cbita. of. upper. of. part. Hokkaido. AKATSU,. Nupinaigawa. and. However,. 1972).. Therefore. Peninsula｡. this. the. pre-. Portlandia. of the. limit of distribution. southern. Formation. districts,. sandstone. &. (KANNO. south the. 1962) ; in. ltsuka-. the. of. Kamenoo. the. Fauna. tokunagai. alternation. MomlJlyama. and. Hokkaido,. reported. Kosho. Hikatagawa. in the. and. (Hataiyoldia). 1967) ; in (KAMADA,. (KANNO,. 1964) ;. to. in the. areas;. Fukushima. been. never. PortlandL'a. sea,. Prefecture. Taiki-machi,. of. area. sent. in the. It is. assemblage Basin may. present. the. at. assemblage. molluscan. northern. OGAWA,. has. fauna. the. and. nearly. may. different. Formation. &. mudstone. the. Prefecture. Tokyo. Takinoue. (KANNO. Bay. several. Caol丘eld,. Joban. may. of. Paleo-Seto. the. ichi Basin,. the. south,. many. tokunagai･. and lchishi Paleo-Seto. the. of. beseen. the. composition,. Group.. Besides is also. swell. assemblages. showing. not. the. situated. two. Sagami. in. bay. distinctly. characteristic. lchishi the of assemblage are located groups geographically. both. although. di庁erence. and. compositions. the. to. opened. steep. very. the. Of. a. Sbidara,. Mizunami,. marglnS. the. specific. such. the. of. this assemblage former. (Hataiyoldia). contains. the. Although,. Group,. Portlandia. facies. alternation. diversified. highly. a. Group. basins. three. the. of. have. that. other,. having. occurrence. Morozaki. 13. Group. Yakuoji (1970).. the. SHIBATA. with. inner. regarded by. rounded. common. the. in. to. Geographically,. along. is. which. Y4. according. species. differs from. Loc.. and. Morozaki. Miocene. the. of. Fauna.. Conclusion The. Morozaki. molluscan speci丘c. the. of PortlandLla. (Aelga). besshoense,. Portlandia bathymetric. divided. each. But. compositions.. name. The. of. assemblages. occurrences. ploma. is. Group. the. Mizunami. Morozaki diBned. Group. Group by. are. SIiIBATA. present. ranges. of the. closely. somewhat. (1970). present. similar and. fauna. (perhaps (1960) in the The to. the. in. other. each by. The. etc･. writers. proposed. Fauna.. zoom. related.. from. and. characterized abundant PeriYoldia (s. s.) sagittaria,. inermis,. tokunagai. formations,. is. group. (Hataiyoldia) Malletia (s. s.). (Hataiyoldia). is. slightly different. are. unit. four. into. tokunagai,. is estimated than roughly more Linthia ITOIGAWA assemblage of the. lithologically. the. inferred. about Oidawara. 600m).. molluscan. fossil. from. mudstone. member of. assemblages. Neilonella-Periploma. Net-lonella-Palliolum. molluscs Portlandia-. The. asseblage. of. of the. assemblage ITOIGAWA. &.

(15) 14. T.. SIiIBATA. (1973). sedimentsI Morozaki. Group. The. However, in. Portlandia. Joban. Coal丘eld,. be. the. of. Basin,. ; in. the. southern. limit. Description. Malletia. Malletia. Leda. 1925. 10, 1935. inermis pl.. YoKOYAMA,. Jour.. Coll.. ADAMS,. &. s.. 9,. alter-. Formation. of the. Fauna.. tokunagai. 1858 1832. str.. (YoKOYAMA,. Ⅰ, Figs.. (Pl.. species.. Kosho. the. the. of. gastropod in. Kamenoo. MouLINS,. (s. s.) inermis. that. species. Malletia. Subgenus. many found. (Hataiyoldia). selected. DES. from. part. in. ADAM･S. enclosing. Formation of the Takinoue Hikatagawa the sandstone and area Hokkaido. The is present. upper and. of. Malletiidae Genus. in the. Portlandia. of. and. is als-o ;. and. different. quite. Taiki-macbi,. of. Family. are. diversity. districts;. mudstone. compositions. specific. Pref.. Tokyo. Pref.. EASE. Fauna. tokunagai. Takinoue. and. NupinalgaWa to. assemblages high speci丘c. Fukushima. MomlJlyama. thought. these. ltsukaichi. the. of. the. viewpoint. having. T.. and. the. (Hataiyoldia). nation. of. from. SIIIKAMA. 1925). 10). Sci., Imp.. Uniu.. Tokyo,. 4=5, art.. vol.. p. 9-. 7,. 2,丘gs.ト6,. Nuculana. inermis,. NoMURA,. Ho-on. Saito. Kai. Mus.,. Res.. Bull.,. 5,. no.. p.. 207,. pl.. 16,fig.10. 1964. inermis,. Malletia 81, pl.. 1967. 1,丘gs.. Malletia 丘g.. 17;. (Neilo). &. Sci.. OGAWA,. Tokyo. Rep.,. Kyoiku. Daigaku,. sec.. C,. no.. 8. KANNO,. inermis,. 2,丘gs.. pl.. Malletia. 1970. EANNO 7,. Hidekata. Prof.. Mom.. Vol.,. p. 400,. Sci., Na･goya. Uniu.,. vol.. Shibata. pl. 1,. 1-3. inermis,. (Malletia). S=IBATA,. Earth. Jour.. 18,. pl.. 1,丘g.2.. Description. Shell. :. in outline. ′oyal. length. three-fourths lCurVed. posterior. and Surface. Hinge half;. inwards.. from. 6 distal. ones. Dimensions. (in mm). height.. lines. half. relatively. de丘ned. No and. large.. broadly. lunule. 25 small Resilifer. and. teeth. on. the. postrior. absent.. Valve. GIYU. 103-1. Right. 20.0. 13.5. GIYU. 103-2. Right. 14.2. 8.6. GIYU. 103-3. Left. 17.0. 11.4. FIYU. 103-4. Left. 18.3. 11.0. 10. rounded. escucbeon.. :. Coll. No.. About. and. Anterior. straight.. margln. specimens. Length. at. hand. were. Height. examined.. When. to. one止alf. opisthogyrate,. almost. Ventral. at. situated. slightly. marglnS. transversely. compressed,. Beak. low,. and. curved.. anterior. thin,. genus,. as. end,. gro∇th on. former. of the. the. long. posterodorsal. regularly. except丘ne 9 teeth. about. as. anterior. Antero-and. smooth. Remarks:. twice. marglnS. with. for. moderate. Length. Yokoyama.

(16) Fauna. Molluscan. described. this. Formation. in the this. cterized large regard. the the. (Neilo). the lcbishi latter. inermis.. name. now. is related having. to. by. the. ridge. living. OKUTANI,. takaii. is distinguishes. by. Occurrence:. in. M6,. Bay,. the writers. on. specimens from. is distinguished little. a. Japan.. KANEIIARA,. Poronaica,. Y13,. anterior. of. U3.. 1890. (YoKOYAMA,. 1890). 3). Palaeontgr･,. YoKOYAMA,. poronaica. 36,. vol･. Geol.. Jour.. 195-196,. p･. Geogrリ. VOl･. 31. 25,軸･. pl･ 14,. 3A,. nos･. p･. 114.. 15,五gs.. pl.. chara-. relatively. this species, also resembles broader anterior end･. DALL,. (Pl. Ⅰ, Fig.. 159,. in size,. to. shell and Y3, Y4, Yll,. (Minormalletia) poronaica. Malletia. Malletia. but. extending. Minormalletia. Subgenus. 1937. and. (1970) based. one,. Sagami. compressed M8, Y2,. more. M5,. M2,. Nuculana. shape. he. corner.. posteroventral. 1890. Kamenoo. inermis,. small. are. SHIBATA. present. distinct. a. Leda. elliptical. hand. on. Miocene. the. of. shell,. described. takeharai,. in. species. Malletia but. tO. Group,. the. smooth-sufaced specimens. from. specimens. under. the. belonglng. as. Malletia from. by. species. the. on. Coalfield. Joban. Although. size. it. based. species. 15. Group. Morozaki. Miocene. the. of. 1951. Neilonella. 1952. Malletia. poronaica,. UozuMI,. 1953. Malletia. ♪oronaica,. TAKEDA,. Mine. OyAMA,. poronaica,. Cen.. Geol., Res･,. Studies. 4,. vol･ 12,. no･. 20,. Geol･,. Coal. on. 5,. nos･. p･. 6,pl.. no･. 6,丘g.. 6,畠g.. pl･. 1. 1.. 3,p.. 72,. 73. 25th. Anniv･,. 8,. pl.. figs.. 2-10. 1963. Neilonella. Description in. elliptical. Shell. :. end.. Anterodorsal. round. anterior. obtuse. margin. ; pOSterOdorsal. margln. half;. both. Resilifer. Dimension. Valve. GIYU. Left. yokoyama province, present. 103-5 one. Formation. Yamami. from has species. Vol･,. 31,. p･. the. is. left. almost. but. teeth. to. forming. an. curved･. Hinge. the. posterior below. on. other. each. with. anterior. descending. broadly. connected. deep. protruded,. from. straight,. 23 small. and. slightly length. gradually. margln. teeth. sinus. narrow･. is. Length. Height 8.4. 13｡3. internal identical. Oligocene. known. characterized. by. collected. mold to. Poronai. been. hitherto. not. half. inequilateral,. :. Coll. No.. Only. long,. Ventral. hinge. Pallial. absent.. (in mm). Remarks: the. posterior. and. anterior. Beak. one-third. margin. with. umbo.. heigbt･. about. inflated,. well. straight, and. almost. posterior margln. anglewith 8 teeth on the anterior about. the. Japan,. genus,. as. at. situated Short,. the. long. tⅦ･ice as. forwards,. and. for. in size. small. Length. outline｡. inwards. curved. Soc･. Paleont.. 3a-c.. 51,丘gs.. pl.. MATSUMOTO,. Poronaica,. this. an. species･. in. Formation from. from. other. inflated,. lower. the. This. species. part glVen. Sorachi-gun･. localities. in. elliptical and. of by. Ishikara. Honshu･ comparatively. The.

(17) 16. T.. small. Bathymalletia. shell.. chitensis, described former two are species. the. rostrated. posterior species, but the. this. Occurrence. in this. latter. Genus. Malletia has. in且ated. Bathymalletia. GIYU. stored. Beak. KuRODA. ⅠⅠ,Figs.. anterior. forming. curved･. binge. an. smooth. umbo disposed. teeth. two-thirds Dimensions. in. (in mm). and. shell. present. from. it.. to. growth. and. below. teeth. broken.. is moderately a. with. Height 8.0. GIYU. 103-7. Right. 10.5. 6.9. species. outline,. more. is. from. present. species. margln,. and. in. the. sea. having. shallow. specimens. is. species. less. related. closely. tvo. only. absent.. of left internal having subquad-. by characterized inflated flat posterior shell, and to BathymalletL'a inaequilateralis. new. or. reported. by. represented. This. valve.. weak月.exure. Resilifer. Length. Valve. This. straight. posterior anterior and largest the beak, and. smallest. Anterior. connected. long,. Vhich. Both. corner.. end,. :. oval. more. groove. but. offTosa,. behind. shell. the. ridge. the. latter. outline,. (HABE),. extending. anterior Occurrence. :. rostrated. from. umbo. Y9.. Neilo. Neilo. morozakiensis (Pl･. Holotype: stored. in. GIYU the. 103-8,. GeologlCal. ADAMS,. Ⅰ, Figs.. ll,. 1852 sp.. a. differs. species more. The. area.. end.. Genus. and. lines. and. rather. margln,. posterior. row;. margln. outline･. posterior. straight. 12.0. species the. nearly. the. Left. right. posterior. from. 103-6. species. livlng. length. in. subquadrate. GIYU. Remarks:. rate. with. posterior. Coll. No.. mold. inflated,. Short,. for丘ne. from. collected by K. TAKEDA National University.. the. posteroventral a. length. the. angle. except to. nov.. Posterodorsal. angle.. right. 1971. 12). thin,. margln. obtuse. from. extending. to. similar. shell.. HABE,. sp.. Yokohama. three-fourt､bs. at. at. margln. Surface. Japan,. of left valve,. size,. Anterodorsal. &. ll,. mold. institute,. moderate. anteriorly. running,. at. Shell. inwards･. curved. internal. Gedogical. :. situated. with. 103-6,. the. Description. is. (YoKOYAMA) small. and. chitensis. (Pl.. and. of. species. but this species, with comparable from in baying broadly this species. (s. s.) inermis. more. living. a. are. paper,. Bathymalletia. in. (HABE),. distillguished. margin.. EASE. Y4.. :. Holotype:. T.. and. inaequilateralis. B.. and. SHIKAMA. nv.. 12). mold external of left valve, c,ollected by K. TAKEDA lnstitute, Yokohama National University..

(18) Molluscan. Description. anterior. end. posterodorsal. one. by. ornamented. 1ated,. regularly. threads. in. present. area. disk ;. two. runs. from. to. umbo. distinctly. Dimensions. point. Internal. 103-8. Remarks: mold. centric by. ridges. lack. to. the. of. 1ng. the. this. species. shell. uozuMI. and. to. of both valves molds Province, of lshikari. 3), the. text一色g. to a. the. show. by. cterized and. strong. Neilo. but the or. is. The. distinguished. from Neilo. characteristic Asiatic. areas. Occurrence:. species. new. as. far. MIO,. Family. latter. the. the. the. GentlS. Yoldia. ADAMS. &. M〔比LER,. ADAMS, 1842. not. and. mudis. chara-. species. kakimlL,. shell lengtb･ areas. 569,. portion,. to. adjacent. Y6.. Nuculanidae. (p･. posterior Portlandia. rostrated. shorter. from reported know. writers. Forma-. (1972) reported. specimen. not. the. on. NupinalgaVa. above-mentioned. in baying. based. destroyed. AKATSU. Their. outline, belong. been the. as. to. resembles. the. has. shell seems. and. &. Miocene. description･. without. ridges. concentric present. species. however,. illustration. be. un-. Consider-. basis･. his to. is. Sakakizawa. and. seem. from. addition. species. kakimii. from. KANNO. Recently,. this. Brm. a. Morai. Judging. in. ornamentation,. (Portlandella). subquandrate. elongately. on. of surface Neilo･. Miocene. characterized. sculptures of. con-. sharp. With. is typically. structure. of his specimens. same. of the Hokkaido,. Neilo. by. characterized. margln. determined. the. from. is. concentric. genus. outline.. original shell. of Biro-gun,. stone. escucheon. left external. one. only. species. posterior. mode. the. by. new. binge. be. Hokkaido.. area. marginal. specimen. complete. 14.8. represented. the. Portlandia. external tions. As. peculiar. described. (1957). 24.5. threads･. cannot. belong. to. seems. ridge. weak and. Height. of strong. end.. position. outline. from. ridges. Lunule. Length. rostrated. oblique. posterior. its taxonomic. known,. shell,. presence. resilifer and. rostrated. Posterior. ridges･. Another. area･. lamel-. concentric. posterior. margln･. This. specimens･. interspatial. and. these. curved･. unknown｡. is. species. in且ated. and. characters. present. fragmental. subquadrate. to. curved. slightly. are. numerous丘ne. blunt. a. anterior. of. ;. straight･. almost regularly broadly. wbicb. posterior. Left. The. four. and. by. Valve. Coll. No. GIYU. margln. the. i.. (in mm). Ventral. oblique. ln. radially. median. lmpreSSed.. and. separated. and. sulci impressed. weak. margln. from. length. and. sloplng,. ridges,. sub-. slightly protruded,. Anterior. less且exured. or. interspaces. their. one-third. gently. concentric more. depressed. prominently. Short,. inequilateral,. about. subtruncated･. and. in且ated, Beak. at. 17. Group. height.. concave.. numerous. spaced,. as. situated. slightly. obliquely. long. as. Morozaki. slightly. size,. twice. long,. margln. posterior. surface. of moderate. Length. Miocene. the. of. and and forwards, Anterodorsal margln. inwards. curved. and. Shell. :. in outline.. quadrate. Fauna. 1858. but. None to. to. of. Japan.

(19) 18. T.. SHIKAMA. Subgenus Yoldia. Yoldia. Ⅰ, Figs･. 1955. F. 1957. 10,. 2,丘gs.. pl.. sagittaria,. Yoldia. (Orthoyoldia). 9,. Yoldia. 1929,. Description: elongated. 10,. 395,. wide found. and. pl.. medium. to. sinus. somewhat. both. about deep, wide,. (in mm). in. Miocene. not be. differ. not. by. 丘ne. in. outline.. Ventral. pointed･ concentric. 35 in anterior. grow･th. Lunule. and. 103-12. Right. 41.3. 20.3. 103-13. Left. 47.8. 21.7. GIYU. 103-14. Left. 61.5. 25.5. GIYU. 103-15. Left. the. is. species. represented to. Miocene. Mizunoya. represented. by. (1957). pointed. posterior Orthoyoldia, but specimens. s･). laudabilis in. It. to. from. Yoldia･ collected. YoKOYAMA. this. and. species. anterior. and. collected. margin. therefore. also seems. grouped. from. tO. this. discussion･. from. type. locality.. Moro写aki in. having･血a･坤hing,e. s･hell. Group. Also,. belong must. somewhat. are. ddtline,but. teeth･. the. UozuMI･,s. However, the. The. Portlandia. and. =okkaido,. specimrens. posterior. lack. Yoldia. of. and YoKO-. by. Coal丘dd.. that. materials. Many. described. Joban. of. mainly. 50 internal. about. first. was. species. fro叩the. COllected. species. one,. by. Formation. collected. have. 24.4. present. imperfect. Cenozoic. distinct. latter. at. Orthoyoldia･. subgenus Group. 20.7. 49. sagittaria･. discussed. specimens. 42. ca.. identical. small sp与Ci甲enS to Yoldia (s･. teeth Pallial. U-shaped.. GIYU. a. Slightly Escucheon. Taxodont absent. 26 in posterior row.. about. and. margln. GIYU. the. 51,fig.. convex.. lines.. 27.9. in. 4,. situated. and gently. 56.0. the. pl.. margln. Right. have. from. Anterodorsal. but. 103-ll. on. p.203,. opistbogyrate,. GIYU. are. Ser.. :. the subgenus on based well-preserved. similar. loⅦ･, slightly. 22.8. the. 7,. inequilateral,. ca.. from. 5.. compressed,. 50.7. to. The. size,. Right. Morozaki. Specimens. large. Right. is. 1,fig.. pl.. 1927,. 103-10. based. species. this. Vol,. GIYU. UozuMI. detail. Mom.. YoKdyAMA,. Height. specimens. margins･. 4;. Length. (1925). type. Univ.,. Valve. and. art.. 191.. 103-9. molds･. yAMA. pl. 25,fig. Sci., Hokkaido. Fac.. GIYU. This. 45,. vol.. Coll. No.. Remarks: extsrnal. Tokyo,. 7). margln･. ornamented. sides;. Dimensions. Univ.. Shibata. Beak. outline･. elongate-1anceorated. in. Imp･. Jour.. 32,fig.. 75,丘g.. of in. Surface. 13). 22, p･ 467,. no･. pl1. Central portion of dorsal Posterodorsal lanceorated, margln concave･. ⅠⅠ,Fig.. Sci･,. Hidekata. ln. nearly. 1925. ll. 247,. p･. p･. Shell. subelliptical. Coll･. Res.,. Prof･. 1926,. YoKOYAMA,. Pl.. UozuMI,. sagittaria,. EANNO,. sagittaria,. (non･ 8;. Cen･. 6,丘gs.. YoKOYAMA,. str.. YoKOYAMA,. 14;. Jour･. UozuMI). 4, pl.. no.. 13,. EASE. ll.. Yoldia. vol. 1967. YoKOYAMA,. sagittari&. 10,. p.. s.. (s. s.) sagittaria. (Pl･ 1925. T.. and. distinctly. it is disting-.

(20) Molluscan. from. uished from. the. ･attenuated Occurrence:. Yoldia. Poronai. posterior. and. Yl,. Y2,. Family Genus. Y4,. DE. Subgenus. 1936. Pro♪eamussium 13,. vol.. Pro♪eamussium. 1953. Amussium 73,. 1955. (Propeamussium) 1, 2, p.. mos.. 1950. Sec.. 2,. in. Left -threads; latter. faint,. to. Right ･spaced, from. slightly. lamellated. umbonal. the. as. Auricles. auricle. length. smaller. prominent. shell. Dimensions. GIYU. 103-16. for. size. long. Sci.. Geogr･,. 6, p. Coal. on. 20,丘g.. Geol･,. 1. 3,. no.. p.. Tokyo. Rep･,. Tert.. Sys.. Univ.,. 2nd. Kyoiku. Dai-. Chichibu. Basin,. 517.. Tohoku. the. Ser.,. 33,. vol.. as. broadly. right,. no.. nine. in. and. to. ventral. lines.. margin,. ventral. from. lines. and. spaced,. the. radial the. and peripheral. part. umbonal. margln. ornamented. Internal. Weak. posterodorsal. posterodorsal. and. running. left, externally. equilateral,. and. growth weak incrementally. antero-. number. umbo. Anterocurved.. with. in the. depressed,. genus,. height.. one. concentric. in. ribs young.er. by. the. regularly. in number,. nine. stage. run. become. and. grows.. unequal, than. (in mm). Coll. No.. Geol.. Jour.. no.. Studies. KANNO,. Rep.,. in running. than. larger. somevhat. in. from. to. slightly. Res.,. Cen.. 32,figs.. pl.. indistinct. distinct,. valve. area. Japan.. TAKEDA,. Sci.. as. and. ribs. URASHIMA,. MASUDA,. concentric. numerous,. five-eights. about. 213,. and ventral in且ated than. slightly former. 17). 6.. kushiroensis,. medium. straight,. Internal. areas.. p.. Height. outline.. the. 1936. 18,丘gs.ト4.. pl.. Shell. valve. 16,. OMORI, circularis 1,丘gs. 10-12.. pl.. 212,. tateiu)ai, 153,. nearly. margin. 27,. no.. Pref., Japan,. Description: ℃ircular. 4,. (Micramussium). 152,. p.. KANEHARA,. KANE王IARA, 5,. kushiroense. (Propeamussium) C, vol.. Propeamussium. 1884. 8.. 7,. Ctenamusium Saitama. 1962. &. 1815. ⅠⅠ,Fig.. tateiwai. MATSUI. prominently. str.. Pl.. 17;. 10,丘gs.. pl.. (Propeamussium) 6,丘gs.. pl.. gaka,. 33-35,. tateiwai,. Propeamussium. 1960. 16,. (1953). umbo.. GREGORIO,. s.. TAKEDA. by. Yll.. (s. s.) tateiwai. Ⅰ, Figs.. (Pl.. Y8,. 19. in having. RAFINESQロE,. Propeamussium. Propeamussium. described. situated. Y7,. Pectinidae. Group. Hokkaido,. of. anteriorly. Y3,. Morozaki. sobrina,. Formation. margln. Hl,. Miocene. the. of. species. related. Oligocene. the. Fauna. and. small,. posterior. and one.. obliquely. Apical. angle. Anterior. truncated.. about. 115. degrees.. :. Valve Right. Height. Length. 9･?. Left. 12.0. GIYU. 103-17. Right. 15.0. GIYU. 103-18. ■Right. 14.0. ･. 9･6. Length. of hinge 6.6. 12.1. 6.1. 14.5. 6.0. ･ 14.5J.. 5.7r.

(21) T.. 20. 103-19. Right. 9.4. 9.5. GIYU. 103-20. Right. 12.9. 12.8. GIYU. 103-21. Left. 10.4. 10.0. GIYU. 103-22. Left. 13.5. 13.6. 7.3. GIYU. 103-23. Left. ll.0. ll.0. 6.0. GIYU. 103-24. Left. 10.0. 9.8. 103-25. Left. 10.5. ll.1. Remarks. One. :. are. valves. shown. of the. exterior. left,. the. of. the. right. its. of. consists prisms. a. of. The Miocene. teeth. crural. thin. present. species. Ennichi. Formation. localities. in. Japan.. to. similar. lack. of. from. the. the. by. this. a,. of. Propeamussium this. resembles. species,. di庁erent. ribs, and Occurrence:. they. but. M2,. Yl,. Y2,. Subgenus. Palliolum. Pecten 47,. pl.. 3,丘gs.. its. peckhami,. the. present. Series. longer. shell outline, both of valves･. MoNTTEROSATO,. because. of. OMORI, and Poronai species･. of Califorllia internal eight. 1884 1930. STEWART,. (DelectoPecten) Peckhami. 6-8.. various. Prefecture, Oligocene. the. from. Oligo-Miocene. sculpture. DelectoPecten. (Pseudoamusium). p'. 56,. the. Y4.. (Pl. 1906. from. (s.s.) circularis of Nagano. distinguished the. it. with. from. TAKEDA,. Palliolum. Genus. compared. Formation. of surface. mode Ml,. be. Komagome. in. (ex-. (MS),figured (s･s･) inouei OMORI, by described OMORI (1955). ProPeamussL'um. differs. nine. from. reported MocHIZUKI. b. sp.. cannot. from. to. owing. (1936). been. valves.. (ARNOLD). γentral. Ctenamussium. but. cannot. waylandi. has. and. and. be. the. invariably. sample. KANE甘ARA. transnipponica. kushiroense. Hokkaido,. a. commonly. deposition. be. to. of. present by. Korea. Paruamussium. Oligocene. (Propeamussium). Formation. South. and. both. of. exterior. the. described. (1935). OTUKA. species,. uppermost. Amusium. of. (s.s.) sp.. paruamussium. auricles) Brst. ProPeamussium. description. without. the. in. part. ventral. which Therefore, the. ribs. lnequlValve･. is. prismatic imbrication･ minor. only. was. the. layer,. left valve｡. very. ProPeamussium. genus. be broken off during might right valves fragility. The number of internal ribs appears on. edges. the. of. internal. of. it becomes. ; therefore,. the. very. with. the. with. larger. of the. the. of. clusive. are. in. that. (Pl. ⅠⅠ,Fig. 17). part. coincides. and. of both. ornamentations. and. specimens. peripheral. them. overlaps. stated. of. almost. right. slightly. valve. layer. single part. or. and. valve. examined･ internal. the. on. shown. dimensions. the. illustrated. the. of. right. the. of. (1972). WALLER. one. smaller. commisure. in. were. specimens. clearly. are. valves. differences. in. detached. nine. of both. The. molds.. external. and. conjoined. characters. essential. The. EASE. T.. and. GIYU. GIYU. The. S王寸IKAMA. Ⅰ,Fig･ ARNOLD,. (GABB, 1869). 18) U.. S.. Geol･. Surv･,. Prof･. Paper,. no･.

(22) Fauna. Molluscan. Pecten. 1925. 8,. Pecten. 1931. Pseudoamusium 4,. pt･ 1934. 125,. 1-3,. Peckhami,. 5,丘g.. threads. left. as. one. (in mm). the. Trans･. Soc･. area. genus,. ilo. is about. with than. smaller. auricle. Length. 18.5. 11.3. of. OMORI. the. Pecten. &. (1954). UTASIiIRO. details,. threads shell. the. that. stated and. threads,. radial. that. the. as. by. in. seen. Pliocene. the. Pecten. discussing. lines,. growth. smoothly. but. corrugated YoKOYAMA. tairanus are. specimens. line. is characterized. concentric. shoⅥ7n. are. of hinge. (1958),. ornamentation. undulated. lost. Length. UTASEIRO. and. surface. weakly. material. stated. Height. larger. useally. than. Miocene.. besshoense. distinguished. KuRODA. from. (DALL). (1925),. YoKOYAMA. tairanus. (Hyalopecten?) randorphi. well. :. 19.3. also. notch;. degrees.. Left. without. valve. less. and. 103-27. They. is by. of right. GIYU. with. long. as. byssal. anricles. anterior. almost. ornameted. distinct. a. 67,. p･. line, which. Surface. Anterior. Soc･. 8,. no1. Height. hinge. straight.. lines･. anteriorly. valves. depressed,. of･ the. center. almost. thin,. swollen･. weakly. the. Paper,. 16.0. specimens. vol･. Paleont･. SpecI. Japan,. for the. Proc･. 25.1. (1925).. It is. SuGITA,. 26.2. radial. pl･. Ser･,. 2nd. Unれ,. Rigbt. concentrics those. Imp･. 103-26. in. 21,. p･. 320,. p･. GIYU. Remarks:. 19,. Fujimoto,. Valve. very丘ne. 486,. no･. no･. Coll. No.. species. Shinano,. 41,. vol･. Res･,. HI. Tohoku. Paleont･. incremental. angle. Prof･. 7-9･. and. protruded. both. Apical. Dimensions. length. and. and of. auricles. differentiated.. this. 2,. volt. 2A･. 44,丘gs･. in size. moderate. Cen･. Comm･,. tairanum, pl･. KAMADA,. shell. of. radial. posterior. Japan,. UTASlilRO,. Rep･,. in. two-thirds. large. 288,. otltline. Umbonal a little behind placed. Beak. very丘ne. by. Shell. :. circular. length.. p･. 12-16･. Peckhami. 287,. p1. 7.. about. as. 47,. no.. 68,. equilateral,. Soc･. 1, 4-6･. Pub･. Sci.. 18,丘gs･. pl･. &. 14〉丘gs･. pl･. MASUDA,. 159,. DelectoPecten pl.. Geol･. 3,丘gs･. pl･. Jub.. 1-6;. (DelectoPecten). DescrlptlOn. as. ags･. Peckhami,. N.S.,. JaPa, 1962. 2,丘gs･ト7;. UTAS=IRO,. 158,. p･. Palliolum. 1962. 2,. Cent･. Geol･. Homma's. Jour･. OMORI. Peckhami,. pl･. 13,. pl･. 2,. no･. Sec･. Tokyo,. Uniu.. KuRODA,. OliSE,. Peckhami,. 10-13;. peckhami,. DelectoPecten 33,. 7,. pt･. 99･. (DelectoPecten). Palliolum. 45,. vol･. 4,丘gs･ト4･. pl.. 12,丘gs.ト6;. 1962. 12)丘g･. pl･. 1,丘gs･. pl. 1958. Tokyo,. Uniu･. Sci., Imp.. besshoense. (HyaloPecten?). (Pseudoamusium). Palliolum. 1954. Imp.. 21. Group. 76,丘g･4･. pl.. 39,. p･. Pecten p.. 393,. p.. Fac.. Jour.. YoKOYAMA,. watanabei. 9,. Sci.,. Coll.. Jour.. Morozaki. 9･. 8,. 1,丘gs･. pl.. 1929. pt.. YoKOYAMA,. tairanus. Miocene. the. of. and. the P.. P.. (1931) are related. (D.). recent. macrocheilicola. all. junior. species. :. M4,. of this. Palliolum. (Delectopecten). HABE. in having丘ner. MIO.. Family. Periplomatidae. DALL,. P.. synonyms. ornamentation.. Occur王･enC､e. (1929),. YoKOYAMA. watanabei. 1859. species･. surface.

(23) 22. SIiIKAMA. T.. Genus. Periploma. Aelga. Ⅰ, Fig.. Tellina. 1924. 1929. besshoensis. 14,. p.. Tellina. 388,. p.. Perploma 10,. 2,. pl.. MAKIYAMA,. 6,. art.. 153,. p.. TAKEDA,. 1955. Periploma. besshoensis,. HIRAYAMA,. 4,no.29,p.107,pl. yokoyamai,. (Aelga). 75-77,. 6,figs.. pl.. C,vol. 1972. yokoyamai,. 1a,. b.. 2a,. thgyrous, long. and. obliquely of. were. two. specimens. sured. blished reported. the. 2,. Sci., Kyoto. Colt.. Imp.. Coal. on. Rep.,. 3,. GeolリnO.. Tokyo. Arts. Kyoiku. Debt.,. Mie. Soc.. Japan,. UniLl.,. Paleont.. Sci.. Mem.. for. Umbo. the. genus,. dorsal. margln.. curved,. 1,. no.. 8,. broadly. Surface. curved by. ornamented. Umbonal丘ssure. Lunule. present.. Sec.. 5,figs.. pl.. nacreous,. nearly opis-. slightly. Anterodorsal. margln. margln one. posterior. and. 5,. narrow,. Posterodorsal. arcked.. margin. thin,. very. almost. sinua-. a. feeb､1y. undulated. and. and. rostrated. except. weak. inabsent.. escucheon. :. 46.0. GIYU. 103-29. Right. ca.. 48. 38.3. GIYU. 103-30. Right. GIYU. 103-31. Left. 40. the. collected. but. swollen. Asagai. discussed to. yokoyamai. (1929). under. the. Formation. this. Periploma. right. from. mainly. (1924) established. (1931). PeriPloma. 43.0. 52.0. Oligocene. Tellina,. Height. 43.0. specimens. YoKOYAMA. YoKOYAMA. γol.. Vol.. Daigaku,. no.. 103-28. more. C,. Paper,. Kyoiku. Sci. Mus.,. Nat.. centrally,. slightly. regularly. Tokyo. placed. the. and. Rep.,. GIYU. and. vol.. 6.. Spec.. Spec.. 63. to. B,. Sac.. Daigaku,. ca.. from. 3,fig.. pl.. Length. About. C,. Ser.. Uniu.. Right. species. by. vol.. Valve. not. beak,. Sec.. Coll. No.. KuRODA. belongs. Tokyo,. Liberal. size. margln.. lines,. examined.. Subsequently,. in. Ventral. (in mm). Remarks:. tion. Uniu.. OGAWA,. little above. margln. growth. Sci., Imp.. AKATSU,. &. outline.. one. posteroventral. Dimensions. one. &. large. subtruncated.. cremental. Fac.. KAMADA,. KANNO. a. rising. Anterior. straight.. tion. Bull.. KANNO. posterodorsal. as. 3,. 1-4.. in. ellitpical. equilateral,. art.. Sci.. besshoense,. Shell. I.. DescrlPtlOn. γol. 45,. Studies. ,no.81,pl.3,丘g.19.. Periploma b,. Tokyo,. b.. besshoense,. PeriPloma. as. 3a,. Periploma p.. 1964. Univ.. Mem.. ,丘g.31. ARAKI,. 6,丘gs.. 86, pl.. p.. Sci., Imp.. 154.. besshoensis,. 1960. 14). Coll.. Jour.. PeriPloma. PeriPloma. ⅠⅠ,Fig.. 1924). 1.. 1953. 1960. (YoKOYAMA,. Pl.. Jour.. YoKOYAMA,. 74,丘g.. yokoyamai. no.. 22;. 1935. 1-5.. besshoensis,. 9,. pt. 1934. Yo壬くOYAMA,. 2,丘gs.. pl.. 1817. SLODKEVICIi,. besshoense. (Alega) (Pl.. EASE. ScHUMACIiER,. PeriPloma. Subgenus. T.. and. and. owing. to. of. the. left.. the. basis. name. of. Yamami. besshoensis in. species. than. valve. the. the. stated the. the. on. that. the. Tellina. basis. Caol丘eld.. Joban. the present. nacreous. MAKIYAMA of. Forma-. shell,fis-. (1934). esta-. specimen. once. besshoensis. from.

(24) Fauna.. Molluscan. Karafuto,. north. in having terior. narrow.posterior. and､ distinctly. margln,. The. specimens. have. rostrated. seen. in. (1924) shell. posterior. but. specimens. outline, discrimination Occurrence: M2, Yl,. In. besshoense. YIO,. Specimens areas. as. shells equilateral These variations. and. by. Yll,. is very Y12.. are. YoKOYAMA than. other. characteristics. forms. Y8,. Y4,. pos-. posterior. reported. morpbological two. some. outlines;. more. Periploma. these. of. Y3,. have. others. yokoyamai･. the. -yokoyamai. subtruncated. depressed. Periploma. of. (1960).. shell. slightly. the. the. at. umbo･. various. and. like. margins. KAMADA. and. show. marglnS. bessoense,. posterior in the. seen. also. hand. differs 'from. sinuation. We'aker. opisthogyrated. on. now. Periploma. rounded. margln,. 23. Group. Morozaki. besshoensis. Periploma. that. stated. and. Miocene. the. of. difBcult･. Referenees ARAKI,. Y. (1961) blematica). Prefecture,. 118,. ll. T.. 47,. (1955) Sci.,. IwAl,. Spec･. pro-. Tsu. of. City,. 1,. Vol･. p･ト. Surv･,. S. Geol･. U.. (in Japanese),. 1. 1-96,. p･. (1959):. Chita. Peninsula,. Daigaku, M.. (1957) Sci.. waters.. ∫.. Note. :. Rapt.. (1960) : Jour.. SHIBATA,. and. 29,. molluscan. 5. Univ.,. Jour･. 30,. GeogrリVOl1. Islands. Japanese. the. and. Sagami. of 2,. 8,. 2,. no.. Paleoenvironmental. Bay. the. northern. Tokyo. Kyoiku. and Soc.. Geol.. adjacent. pls･. Group, 6. 246-300,. change Mem.. 3. Mizunami p.. its. and. 61-94,. 15, p.. no.. Miocene. the. vol.. (in Japanese).. in. ReP･,. pls.. of. Univ.,. fossils. Sci.. Japan.. sac.. studies. Nagoya. assemblages. Jai'an･. Formation. Kumura. Geol･. molluscan. fauna. molluscan Nat.. :. its. and. 49-130,. p.. the. H,,(1973). the. the. of. Prefecture,. Paleoecological. Sci.,. JaPan･. fauna. formation. Yokohama. Earth. Japan･. p･ト397･. Fu.kushima. on. in. structure. Prefecture.. molluscan. no.. along. observed. structure Prefecture,. i pl･. 1-7,. sedimentary. of. coalfield, C, γol. 4,. sec.. a sedimentary Aichi Chita-gun,. p.. Aichi. catalogue. Joban. Japan.. 1,. no.. A. (in.Japanese). (1955) : The Asagai. K. region,. 31,. vol.. T.. A. (in Japanese).. tbixotropy. with. related. deformation,. area. adjacent BIRAYAMA,. Pelecypoda,. sbells･. of Eimaka･s.hima,. coast. p.195-200. S. (1973):. on. Univ･,. of California.. pectens. phenomena. plastic. Geogr.,. (Miocene),. ITOIGAWA,. Mie. environs. 37-42.. p.. Miocene. Gaol.. EoRIKOS=Ⅰ,. the. pls.. Japanese. of. 24,. northeast and. HIGO,. Quaternary. 53. Geological. :. no.. (1960) : Jour.. Debt.,. in. 1-192.. T. Earth. the. Arts. Liberal. and. 7-146,. p.. Genera. (1951) :. text-丘gs. HAYASliI,. Tertiary. (1906) : Paper,. Prof.. Bull.. Japan.. (including. structure. sedimentary developed. formations. pls.. R.. EABE,. and. paleontology. Tertiary. the. of. Mie. ARNOLD,. Geology,. =. Central. pls･ based. correlation. Japan,. 8,. nO･. 123-. p･. 134. KANEIjARA,. K.. Geogr., 3-4;. EAMADA,. Y･ Paleont.. EANNO,. S. Central. 13,. vol.. (1937) no.. Neogene. (1936) : On. :. p.. 1-2,. nos.. 155-161,. Soc.. Japan.. from. 31-38,. Chosen. South. (Korea)･. JaPan･ Jour･ ■Geol･. 1､ pl.. fossil. from. shells. Hokkaido･. (Yesso)I. ibid･,. vol･. 14,. The. 1 pl. Te.rtiary. Spec.. Japan,. (1960) :. p.. Tertiary. the. (1962) :. shells. The. Tertiary. Part. 2.. marine. Paper, System Paleontology,. no.. from. mollusca ･8, p. the of p.. 1-187,. the. Chichibu 123-396,. Joba血cOal-丘eld,. Japan･. 21 pls. Basin, 21. pls.. Saitama. Japan.. Prefecture, Soc.. Promot..

(25) 24. T.. Sci., Ueno,. T.. and. EASE. Tokyo. fauna. Mollnscan. (1967) : Tokyo. SIIIKAMA. from. Miocene. the. formations. in. the ltsukaichi. Basill,. Prefecture･. Shibata Mem. Vol., p. 396-406, 2 pls. Prof･ Hidekata AKATSU, Tertiary K･ System developed in and (1972): the Taiki-machi, Bull･ Biroo-gun, Hokkaido 5, p. 2271236, Nat･ 2 (in Japanese)･ Sci. Mus., no. districts,. (1964). Hokkaido,. 269-294, 瓦uRODA,. E･. OGAWA,. and. Fossil. (1931):. Sbinano. T･. HABE. Coll･. Sci･, Kyoto. MAKIYAMA,. ∫. (1934): K･. M･. T.,. illustrated. Paleont･. Soc･. NAKAMURA,. S･ S･. Daigaku,. pis.. Takinoue. and. C,. sec･. Geol･. 81,. no･. p.. T･. 1usca. (1962) mainly. Maru. the. 2,. 41,. Sci.. 5. Rep.,. Biol.. of. Lab.. Matchgar.. and. Mem.. pls.. Tohoku. Univ.,. from. peckhami p.. 10. 6,. no.. for. 2nd. ser,. the. On. Pro-. 20.. p.. from. fossils. revision).. Bay Bull･. Honshtl,. Japan.. pis. from. GABB. and. abyssal. Japan. (in Japanese).. pl. lamellibrancbiate by. waters. adjacent Reg･. Tokai. 58166.. p.. Northeast 2. 1. and. 2,. Southern. (19).. schools. 5, no.. 125-130,. archibenthal. 195511960･. Res.,. Cen.. 193-234,. p･. 486,. Sagami. fossils,. Cenozoic. Shiogama,. 6,. not. no･. the. on. Bay.. 122-166,. p.. part. 8 pis.. from. Mus･). vol･. years. Yotsukura. no.. recommended Chikyu, vol.. (Pseudamussium). collected. during. 27132,. p.. maps. Kai. Sagami. of. the of (1963) : A survey a (primarily nomencratorial. monographs. Vol.,. Report. :. 5,. middle. pls.. shells. of. K.. mollusca. Japan,. sea. Japan.. (in Japanese).. Pecten. Soc･. The. the. of. 13. p.ト90,. Illustrated. :. Topographical. Ho-on. "Geology. 4,. (in Japanese).. classical. Miocene. On. ‥. HoMMA's. of. AsANO,. and. Peninsula. Saito. (1934). OKUTANI,. Momijiyama. the. pls.. (1950). Anniv.. (1926) :. Res･〉. Jour･. I･. 24th. (1935) :. Bull･. 10 Y.. in. Chita. of. T･. Kyoiku. γol.. Pectinidae. HAYAMI,. Japan. OHSE,. Tokyo. molluscs B,. ser.. KANEIIARA. tateiwai. MATSUMOTO,. NoMURA,. from. Part. Asagaian. 117-238,. p.. F･. (1971):. Univ.,. URASfiIMA,. and. Peamussium. part. The. Tertiary. 2,. no.. K.. Imp.. (1962) :. 33,. in. Japanese).. OyAMA,. and. Houshold.. MATSUI,. Rep･. mollusca. Province''(in. Imp.. vol.. Sci･. Japan･. faunas. 4 pls.. T･. MASUDA,. Molluscan. :. Fish･. mol_. the. Res･. R.V.. Lab･,. vol.. SoyoI 32,. p.. 1-40,5pls.. (1968) the. of. archibentbal Fact. Jour･ OMORI,. M.. some. T.. Japan (in Japanese)･ (1929) : Topography Tokyo,. OTUKA,. Y･. Res･. Ⅲ･ Part. M･ in. the. 281-290, TAkEDA,. E. South. :. Fauna. no.. Oti. Graven. peckhami 21130,. the. Cbita. of. in. faunas. adjacent. 27,. no･. 3. p･. areas.. pl. from. Propeamussium. genus. Noto. soutern. Tokyo,. Ichishi. 1. 1-98,. 7-22,. 3 lato. sensu. Japan,. pls. from. collected. pis.. Peninsula. (in Japanese).. J∂〟γ.. 338-345.. p.. Univ･. Imp･. the. Pecten. 19, p.. and. of. 13,. vol. the. Peninsula,. First. Group･. four,. their. habitats. Trams.. Proc.. 4,. no.. p.. Setoncbi. Earth. Part. Japan. 5. 846-909, Series,. 3.. Southwest. Sci., Nagoya. Bull.. pis.. Uniu.,. Japan. vol.. 18,. p.. 4 pls. The. (1962) : South 1. fossils. Ewanto. aムd. Region･. in. the. Paleont.. Neogene Soc.. Katsuragawa. Japan,. Group,. N.S.,. no.. 47,. p.. pl.. (1953). :. The. :. and its Geology. (1975). (in Japanese). (1940): On. M.. 484,. 41,. Molluscan of. Sakhalin K.. TAKEDA,. Inst･,. (1970). 1.. 27-84,. SUGITA,. The. (1935):. Earthq･ SHIBATA,. vol.. On. geology. Bay. p.. no.. Res.,. and. 1,. pt.. 4,. sec･. (1954): Cen･. 17,. vol･. implication. paleoecological. Sagami. of the C, vol･. species. Daigaku. T･. Geogr.,. 2,. and. from. mollusca. sec･. new. Kyoiku. UTASliIRO,. and. UDA,. On. abyssal. Tokyo,. Univ･. Tokyo. RepI. distribution. ecological and. Sci.,. (1955):. Sci･. OzE,. Systematics,. :. Poronai. Yokohama the. recent. Formation. fossil of. fauna･ the. southern. Nat･. Uniu･,. anomalous. (01igocer)e Studies part. Grad･. of Coal of Cbita Thesis,. hydFOgraPhical. Tertiary) Geol.,. Hokkaido. of no.. Peninsula,. Aicbi. no.. 103.. conditions. of. Geol.,. and. l-103,. 3, p.. 13. pis.. Prefecture. (MS). the. Kuroshio.

(26) Mollusこan. in. the. southern. uozuMI,. S.. Fish.. Res.,. Study. Portlandia.. and 7. 22,. no.. (1957):. St.,. Explanation. (1955) :. Cen.. Exp.. Miocene. the. of. off Japan. waters. Imp.. JaPan.. Fauna. in. proper. 10, p･. no.. p. of. the. fossils. four.. fossils. molluscan. from. in. the. (in Japanese).. fisheries. Northern. Japan Part. Eokkaido･. Univ.,. Sci., Hokkaido. Fac.. to. relation. 25. Group. 231-278･. of Cenozoic. 24-31.. Morozaki. 4,. ser･. 2, 9,. vol1. (in Japanese)･ Yoldia. Genera. no･. 4,. 539-596,. p･. pls.. Palliolum. nese. Birthday,. M. 36,. mos.. 45,. :. Sci.,. (1927) : vol.. 2,. 2).. Part. Jubl.. pt.. (1929) :. p.. 191-204,. Molluscan. 3. (Studies H･. Prof.. of. Japa･ 60th. Fujimoto's. of. Internal. der. aus. the. Cong.,. Geol.. 7,. sec.. p.. the. 48-56,. Palaeontgr･,. Kreide･. japanischen. in. microstructures. shell. vol･. the 45,. lowest. part. 3,. 1-22,. 5. pls･. part. of. the. art･. from. the. p1. middle. of the. Joban. Coal･fleld･. Jour･. Joban. Coal･fleldL. ibid･,. EtaibetsI. Jour･. Teshio･. ibid･,. pls. from. mollusca. Univ.. p.. 24th. vol･. remains. Tertiary 4,. signi丘cance. from. Tokyo,. 1-26,. Tertiary. Imp.. Comm.. pls.. remains. Uniu.. 7,. GABB. ♪eckhami. Publ.. pls･. Molluscan. art.. (1926) Fac.. 3. Molluscan. Sci., Imp.. (1925) : vol.. 8. 3-6,. (1924) : Call.. 320-330,. Palliolum. of. mutation. Peckhami,. p.. Pectinacea yoKOYAMA,. the. functional (1972) : The : Bivalvia)･ (Mollusca (1980) : Versteinerungen. T.R.. WALLER,. On. (195S) :. T.. UTAS臼IRO,. Tokyo, shells. sec.. from. Oil-丘eld. the 2,. 1, pt･. vol･. the. Joban. 7,. of p･. Embets. and. 235-248,. 3. Coal-丘eld. of. Haboro,. pls.. 2 pls･ fossils. from. Karafuto･. ibid･, vol･. 2, pt･. 9, p･ 369-398,. 6 pls･.

(27) Explanation Figs.. Fig.. 1,. 2,. 15･. Acila cast. from. a. left. 2.. Rubber. cast. from. a. right. external. 15.. Rubber. cast. from. a. right. external. 3.. Malletia. 4,. 5,. Gypsum. cast. from. a. right. 5,. Gypsum. cast. from. a. left. Figs.. Figs.. Figs.. 7,. Rubber. 8.. Right. 9, 10. 9.. Right. 10.. Left. Malletia internal internal Neilo. from. a. 11.. Rubber Rubber. cast. 16,. 14.. Left. Yoldia. Left 17. Left. 17.. Rubber. 18.. Palliolum. internal. hlOld. from. cast. 19.. Gypsum. 20.. Rubber. Fig.. 21.. Glycymeris. Fig.. 22.. PeriPloma. Right. Gypsum. left. cast. a. from. a. from. Y4.. ×1. Y4.. mold. external. mold. Eolotype. Loc.. xl.5 Loc.. ×1.2. MIO.. external. Loc.. Y2.. (GIYU-103-17) (GIYU-103-26). ×1.2. Loc.. ×1. Loc.. Y2っ. M4.. YoKOYAMA. tokunagai mold. external. (GIYU-103-43) (Aelga) besshoense. cast. Hl.. mold. (GIYU-103-39) (GIYU-103-40). ×1.2 Loc. ×1. Loc.. Y5. Y3.. NoMURA. vesiitoides. valve. left left. Loc. Loc.. GABB. right. a. lil. Hl.. Yll.. ×1. Peckhami. (Hataiyoldia) from. cast. ×1.2. ×1 Loc.. (GIYU-103-38). ×1.5. external. (DelectoPecten). Portlandia. Loc.. KANEfIARA. (GIYU-103-18) a. Loc.. xl.2. U3.. (GIYU-103-8). mold. tateiwai. (s. s.). from. cast. 19, 20･. external. right. Propeamussium. 16.. (GIYU-103-37). mold Ⅱ1.. mold. (s.s.) sagittaria YoKOYAMA mold (GIYU-103-13) mold (GIYU-103-14). ･internal internal. M2.. M2.. Hl.. external. 12. 13,. Loc.. (BINDS). right. a. ×1.3. Y4.. ×1 (GIYU-103-38) (s.s.) inermis (YoKOYAMA) mold (GIYU-103-1) ×1.5 Loc. mold (GIYU-103-4) ×1.5 Loc.. from. M2. Loc.. ×1. (GIYU-103-35) (GIYU-103-36). mold mold. Loc.. ×1. diuaricata. nov. sp. morozakiensis a left external from cast. Rubber. Figs.. external. Loc.. valve. ll, 12.. 13.. Fig.. (s.s.) cえst. Loc.. ×1.5. Loc.. ×2. (GIYU-103-34) mold (YoKOYAMA). external. (GIYU-103-37). valve. Acila. 7.. 14. Figs.. Left 8.. mold. KAMADA. praeniPPonica. 4.. 6. Figs.. external. (Minormalletia) Poronaica internal mold (GIYU-103-5) Ennucula. 6.. (YoKOYAMA) (GIYU-103-32) mold (GIYU-103-33). pictulata. Rubber. Left Figs.. (Truncacila). 1.. I.. Plate. of. a. right. ×1. Loc.. El.. (YoKOYAMA) external. mold. (GIYU-103-29). ×1 Loc.. Y4.. Y6..

(28) T.. S口rKAMA. l. and. T.. KASE. Sec.. 2. 4 3. 10. ll. 13. 14. 16 18. 17. 19. 21 22. 20. Ease. photo.. II, Plate. 1.

(29) T.. S口IKAMA. l. and. T.. KASE. Sec.. 2. 4. 10. ll. 13. 16. 14. 18. 19. 17. 22. Kase. photo_. ⅠⅠ, Plate. 1.

(30) Expl&n&tioTL Figs.. 1, 2. 1. 2.. Figs.. 3, 3.. 4. Fig.. 5.. Fig.. 6.. Fig.. 7.. Figs.. Fig.. 8,. Macoma. Left. sp.. (GIYロー103-44) ×1 Loc. Hl. (GIYロー103-45) ×1 Loc. Hl. 4･ Venericardia YoKOYAMA (Cycloeardia) cf. tokunagai Left valve (GIYU-103-46) xI Loc. M7. Right (GIYロー103-47) ×1 Loc. M2. valve Venericardia (Cyclocardia) ci･ siogamensis (NoMURA) Left valve (GIYU-103-4白) ×1 Loc. Hl. Calyptogena chitanii (KANEEARA) Left valve (GIYロー103-49) ×1.5 Loc. Y3. Acila (Truncacila)?ictuLata (YoKOYAMA) from Rubber a cast left external mold (GIYロー103-50) 9･ Portlandia YoKOYAMA (Hataiyoldia) tokunagai. 8.. Gypsum Gypsum. valve. cast. from. a. left. cast. from. a. right external MAKIYAMA. Dentalium. yokoyamai. (GIYU-103151) Figs.. ll, 12･. ×1 Loc.. Bathymalletia. 11.. Left. 12.. Right. Fig.. 13.. Yoldia. Fig.. 14.. Pert?loma. internal. Fig.. 15.. Acesta. Fig.. 16,. Gypsum. external. mold mold. cast. PI.. I, Fig.. 13,. besshoense. from. cast. a. Rubber. 17.. Left. 18.. Linthia. cast. from. internal. a. and. nip?onica. (GIYU-103-53). xI. right. right. Y5.. Loc.. Y5.. xl.5. Loc.. Y9.. xI. external. internal. right external YosHIWARA Loc.. ×1.2. (YoKOYAMA). Y.5.. ×1 Loc.. (GIYU-103128). mold. (Acesta) goliath (SowERBY) Right valve (GIYU-103-52) ×1 Loc. 17･ Pro♪eamussium (Pro♪camussium). 16.. Loc.. ×1.3. nov.. sp.. mold. of. H2.. ill.. chitensis. (Aelga). ×1 Loc.. (GIYロー103-41) (GIYU-103-42). (GIセu-103-6) Holotype valve (GIYロー103-7) ×1.5 Loc. Y9. (Yoldia) sagittaria YoKOYAMA. Rtlbber. Fig.. II.. valve. Right. 9.. 10.. Plate. Of. Y4.. 班lo. tateiwai mold. mold. KANEHARA. (GIYU-103-20) (GIYU-103-16). xI. Loc.. Y2.. xl.5. Loc.. Y4..

(31) T.. S甘IKAMA. and. T.. KASE. Sec.. 4 8. Kase. photo.. Il, Plate. 2.

(32)