A Monograph of the Collignoniceratidae fromHokkaido Part Ⅲ : Studies of the CretaceousAmmonites from Hokkaido and Saghalien-XX

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Kyushu University Institutional Repository

A Monograph of the Collignoniceratidae from Hokkaido Part Ⅲ : Studies of the Cretaceous Ammonites from Hokkaido and Saghalien-XX

Matsumoto, Tatsuro

Faculty of Science, Kyushu University

https://doi.org/10.5109/1543680

出版情報：九州大學理學部紀要 : Series D, Geology. 19 (3), pp.297-330, 1969-11-10. 九州大学理学部

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pp．297−330， text−figs．1−14， pls．39−45， Nov．10，1969

AMonograph of the Co1Hgnoniceratidae ffom Hokkaido

Part III

（Studies of the Cretaceous Ammonites from Hokkaido and Saghalien−XX）

By

Tatsuro MATsuMOTO

Abstract

Part III contains the systematic descriptions of the subfamily Barroisi−

ceratinae． The hitherto used framework of classification of the Barroisicerat−

inae is to some extent modi6ed． Bα88θocθγα8 C旺LIGNoN，1965， is regarded as asubgenus of Bαγγoτ8i6θゲα8， whereas Tθ出α8ぜαis separated as a distinct genus．

Anew subgenus of Foγγθ8εθ万αis established which is characterized l）y a smoothed outer whorl． This is morphologically transitional to more evolute yα6θi6θγα8， which is settled as a specialized offshoot in the Barroisiceratillae．

The described species from Hokkaido are altogether seven：−a new species of Bαγγo衙6θγα8 （Bα88θ06θγα8）， two species of Foγγθs亡θ冗α （Foηθ8￡eγ α），

including world−wide 17．（F．）α伽α履Z in a revised sense and a new one， two new species of a new subgenus of Foγγθ8￠θ励α， a species ofγαbθづ6θγα8 and a species of 17αγZθ社θ8． In connection with the descriptions of the barroisicera七ine ammonites from Hokkaido， comments are generally given on many genera and subgenera， and also on some species occurring outside Hokkaido．

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Manuscript received July 5，1969．

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Systematic Descriptions

（Continued）

Subfamily Barroisiceratinae

The subfamily Barroisiceratinae BAssE，1947， were comprehensively studied by REEsIDE（1932）and BAssE（1947）． The framework of the classi6cation used

in the Tγθ硫8θby WRIGHT（1957）is in principle acceptable， as was previously

supPorted by REYMENT（1955）． There are subsequent works which should be taken into consideration， such as those of YouNG （1963）， PARNEs （1964），

］M［ATsuMoTo et al．（1964）， CoLLIGNoN （1965） and the late Dr． vAN HoEPEN

（1968）．

Although the Cretaceous deposits of Hokkaido are not so prolific in the Barroisiceratinae as those of Madagascar， our recent collections， aided much by Mr． T． MuRAMoTo， contain some interesting examples． As a result of the study of them and also the survey of previous works， I modify to some extent WRIGHT s scheme of classi丘cation．

In view of the high variabiIity of the barroisiceratine ammonites， as demonstrated by BAssE s（1947）6ne work， too much splitting in classification

should be avoided． Several superficially distinctive groups of species are treated as subgenera， whereas a few apparently resembling ones are separated as distinct genera， inasmuch as there are suf6cient reasons．

The Barroisiceratinae are typically represented by Bαγγo乞8Zcθγα8 and range in shell characters from comparatively more compressed， feebly ornate or smooth−

ish genera， such as Solgθγ伽8 and丑αγZθ屹8， to more in且ated， strongly ornate ones， such as Fo θ8亡θγ α（s．s．）alld S励bαγγoZ8icθγαs． Two major stocks， one without and the other with mediolateral tubercles， can be distinguished in the

subfamily， but the mediolateral tubercles themselves may become apparently

variable in the case when the smoothing of flanks takes place（as in Solgθγ屹8 and丑α冗θZτθ8）． In other words， the af丘nity of Bαγγo乞8Z6θγα8 with a smoothed outer whorl（e．g． Bα88θooθγα8）and that of Fo宵θsτθγZαwith smoothed flanks

（e．9．Solgθγπθ8） may be confused unless the ontogenetic change of characters in the inner whorls is carefully inspected． Many species of the Barroisiceratinae have fairly or very involute shells， but Foγγθ8君θγZαincludes less involute species．

yαbθZ￠θγα8is regarded as a specialized offshoot of the Foγγθ8￠θがαstock charac−

terized by evolute shells， more or less depressed and strongly七uberculate septate whorls and a smooth body−whorl． A new subgenus（2∪「τLγα7η0￠0α）of 170γγθ8τ碗α to be established below seems to represent an intermediate form between 170γ一 γθ8εθγZα （s．s．） and yαbθZ6θγα8． Sutures are also considerably variable in the Barroisiceratinae． Those of BαγγoZ8Z6θγαs may show the average pattern， al−

though they vary to some extent in themselves． Comparatively reduced patterns

are seen i11∬αγ1θ舵8， whereas more deeply indented ones characterize 8励bαγ一

γoZ8τ6θγα8 and yα6θτ￠θγα8．

The origin of Bαγゲoτ8Zcθγα8 isl certainly in S励p万oη06y￠伽80f the Upper Turonian， as has already been mentioned by WRIGHT（1957， p． U32）．1〜θθ8鰯￠θ8

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AMonograph of the Collignoniceratidae from Hokkaido． Part III

WRIGHT and MATsuMoTo，1954， another derivative of Sμ吻乞oη06〃鋤80ccurring

near the Turonian−Coniacian boundary， indeed resembles Bα宵oZ8i￠θグα8 in some respects but is more closely related to劫bpγZoηoc〆μ8， as has been described

in detail in Pαγ￠10f this monograph（MATsuMoTo，1965， P．62）． It could be

possibly a passage form between S？L吻γ oηoc〃61μ8 and Bα㌍γoi8乞6θγα8， but I am rather inclined to regard it as a dead end offshoot of S％bP弼oη062／61μ8， because its much compressed shell−form， Hexuous ribs， bullate umbilical七ubercles， and

modi6ed pattern of sutures imply deviation from the normal characters which

connect Bαγγoτ8乞cθγα8 with S秘伽弼oηρo〃clμs．

A］most all the genera and subgenera of the Barroisiceratinae are strati−

graphically confined to七he Coniacian， except that Tθ鋤8iαis informed by YouNG

（1963）to range up to the Lower Campanian．

The zonal succession of various species of the subfamily in七he Coniacian has not yet been well estal〕lished， inspite of their frequent occurrence in certain

areas． According to Co肌IGNoN s （1965）atlas of characteristic fossils in

Madagascar many of the illustrated species belonging to BαγoZ8τcθγα8（s．s．），

S励bαγ㌍o乞s乞cθγα8，Hα弼θπθ8， Foγγθs￠θ？・iα （s．s．）， YαbθZoθγαs and SoIgθγττθ8（two

species）occur in the Middle Coniacian zone of瓦088仇α臨θγα8毒んθobα臨αημ伽一

Bαγγo 8Z￠θγα8 0γz江αん2ノ￠η8θ， several of Solgθγπθ8 ［＝Pをりθfθαμ0￠￠γα8］ and Bα88θo−

6θゲα8in the UpPer Coniacian zone of Pγ乞oηo￠yclo6θγαs gμ〃αbαημ仇一Gα励ん乞θガ6θγα8 仇αγgαθ，whereas three species of Yαbθi6θγα80ccur already in the Lower Conia−

cian zone of P￠γo傭θγα8由励輪襯． Whether this succession is everywhere main七ained in Madagascar and other regions or otherwise should be examined

by further study． The available evidence in Hokkaido is not su伍cient on this acco皿t． All the species from Japan occur in the zone of 1％06θγα働秘8％ωα∫ 一仇θη8i8． In our present knowledge it may be broadly stated that most of the

barroisiceratine genera and subgenera seem to have been rather suddenly dif−

ferentiated directly or indirectly from the common ancestor，品bpγ40ηoo〃61μ8・

The geographical distribution of the Barroisiceratinae was summarized by

BAssE（1947， p．161−170， especially text−figs．6−7）， who concluded that they are distribu七ed in a considerably wide belt on both sides． of the postumed Late

Cretaceous equator． Japan was not included in her distribution map． The

occurrence of various species belonging to various genera and subgenera of the

subfamily has become distinct in the present study． Hokkaido as well as the

Pacific side of Northeast Japan must have been under the influence of七he ocean curren七from the south in addition to七hat from the north or northeast．

The reason why the Barroisiceratinae have hitherto been overlooked from

the study of the proli且c Upper Cretaceous of Hokkaido is， in my view， in facies

problem． In Hokkaido as well as in Northeas七Japan，七he barroisiceratine

ammonites occur almos七exclusively in comparatively shallower， more or Iess

sandy（and glauconitic）open−sea sediments but are extremely rare in probably

off−shore muddy sediments． While the strata of the Iatter facies are widely

distributed in Hokkaido， those of the former facies are limited there．

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Genus BαγγoZ8τcθγα8 DE GRossouvRE，1894

欠〃Pθ一8Pθo θ8・一∠4γηηzoγτ党θ8 んαbθ7プθZZ？zθγZ］旺AuER，1866 （subsequent designa−

tion by SoLGER，1904）．

Gθηθγ乞6伽gη08ぜ8．−Whorls are moderately involute， more or Iess higher than broad， and usually broadest in the lower part（i．e． near the umbilicus），

having compressed to considerably inHa七ed flanks and a rather low， roof−shaped venter． The ventral keel is typically strong and七he clavate ventral tul〕ercles give rise to distinct serration on the keel．

From rather sparse umbilical tubercles arise radial ribs which are alternated with one or two shorter ones． All the ribs form clavate tubercles at the ventro−

lateral shoulder and then projected to the ventral clavi． The umbilical tubercles are typically ro皿ded at least on the inner whorls but may sometimes be bullate．

Normally the radial ribs are rather flat．

AI七hough the suture is considerably variable， the first lateral lobe（L）is

moderately deep and asymmetrically bipartite and the Iateral saddles on both sides of L are massive to subrectangular in rough outline． The number of

auxiliary elements is apparently variable． The saddles and lobes are moderately indented． The main lobules in the two lateral saddles and七he folioles in the

lower part of L may be considerably long and narrow． Other minor incisions

are generally small， showing a rather reduced aspect of the suture．

The size of the shell is small to moderate．

Rθ仇α触．−In the欠γθα万8θ（WRIGHT，1957， p． L432）two subgenera， Bαγ一 γoZsぜoθγα8（s．s．）and Tθぽαs乞αREEsIDE，1932， are included in七he genus Bαγγo乞8ε一

〇θγα8． Flor the reasons described below I think i七be七ter to separate T斑α8iα as a distinct genus and treat Bα88θ06θ㌍α8 CoLI、IGNoN，1965， as a subgenus of Bαγo 8ゼ￠θγα8． The above described generic diagnosis is七ypically applied to the

Subgenus BαγγoZ8 ￠θγαS （S．S．）．

Ihad an opportunity to examine two syntypes of∠4働仇o励εθ8∂θ励ατ06αγ励α一施8R6MER（1852）， the type−species ofτθωα8 αREEsIDE，1932， in七he University of Bonn（G．1．B． No．48a and 48b）（Text−figs．1−2）． The larger and illustrated one （R6MER，1852， pl．1， fig．2a−c） is designated here as the lectotype． The smaller one is of identical species． In these specimens the major ribs which

arise from the umbilical tubercles are somewhat elevated at七he middle of七he

Hank， if not forming distinct tubercles． The ribs are somewhat weakened be−

tween this row of elevations and that of ventrolateral七ubercles． Some of the

ribs show a slight bending at the elevating point． These characters， though indistinct and overlooked by subsequent authors（e．g． LAsswlTz，1904；REEsIDE，

1932；YouNG，1963）， and the compressed whorls with Hattened flanks and also

very deeply incised sutures with an apparently trifid first Iateral Iobe， may indicate a possible afnnity of Tθzα8Zα（1θ励ατo￠αγ仇α診αwith such species as P8θπ∂08c〃lo梛bα6Mα仇θ励oαηα （RENz，1936）（see YouNG，1963）， although七he ventral keel is more distinctly serrate in欠θ鋤8づα．

欠．∂θ励ατocαγ碗α￡αoccurs， according to YouNG（1963， P．120）， in the upPer−

most Santonian and the Iowest Campanian． Tθ影α8Zα鋤γ亡o励（REEsIDE）（1932，

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ー〜 ︑

／，，・

1b

20

20mm −

Figs．1−2． Tα履α8iαdθ励α￠06α㌍仇α￡α（R6MER）

Two syntypes， No．48a（Fig．1）and No．48b（Fig．2）， in the Palaeontological Museum， University of Bonn． Lateral view（a）and whor1−section（b）in diagram−

matic sketch．（T．］M．（1θliγτ．）

︑

2b

p．16，p1．6， figs．7−9；pl．7，6gs．8，9），which is reported as older than T．〔Zθ励α￡o−

￠αγ仇ατα，seems to show slight thickening of the ribs at the mid−flank and weakening above that point． These species are more evolute than typical species

ofBαγγo乞8τcθγ。α8．

REEsIDE （1932， pl．3， figs．9−10；pl．4， fig．3） described under T．（1θ励ατo−

6αr飢α施alarge shell which has prominent and distant ven七rolateral nodes on otherwise smoothish body−whorl． This is a remarkable feature which is not

seen in Bαγγ0ゼ8i6θγα8 （S．S．）．

To sum up欠θωα8Zαconsiderably deviates from Bαγγo 8Zcθγα8．

In the Cretaceous of Hokkaido no examples of BαγγoZ8icθγα8（Bαγγo 8τcθγαs）

have been found， but there is a species which is referable to B．（Bα8sθooθγα8）．

Subgenus Bα88θ06θγα8 CoL・LIGNoN，1965

欠鯛）θ一81）θ6乞θ8．−Bα88θ10cθγα8 col6αηαpZ CoLI・IGNoN， 1965 （original designa−

tion）．

8励gθηθ酩砺α9η08乞8．−This subgenus resembles Bαγγoi8Zcθγα8（BαγγoZsτ一 6θγα8）in the earlier growth−stages， but is distinguished by the disappearance of the ribs and tubercles in more or less late growth−stages． The ventral keel is also weakened and may disappear in the nnal stage． In other words七he ou七er whorl is smoo七hish． Even on the inner whorls the ribs are weakened on the Hank．

Co仇PαγZ80ηα励ゲθ伽αγ s −Bα88θocθγα8 was set uP by CoLロGNoN （1965，

p．73）as a new genus of the Barroisiceratinae． Itrea七it as a subgenus of

BαγγoZ8乞cθγα8， because it is closely related to Bαγγoゼ8Zoθγα8 （s．s．） and because BαγγoZ8ぜcθγα8（s．s．）is greatly variable and some examples show transitional

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features to Bα88θo￠θγα8． In fact， if the imma七ure specimens alone are handled，

it may be sometimes dif丘cult to tell whether they are referred to B．（Bαγγo乞8i−

6θク α8） or to B．（Bα88θOCθγα8）．

ウ

In addition to the type−species I should include ln Bα8sθ06θγα8 more specles which have essentially the same charac七ers as Bαγγo乞8Z6θγα8（s．s．）in earlier growth−stages and lose the ornament in later grow七h−stages．

In B． ooloα物αp all kinds of ornament disappear rather suddenly in the adult stage， as is clearly described I）y CoLI．IGNoN（1965， P．74， pl．447， fig・1826）・壬 But in certain other species， e．g． a new species described below， the ornament

is weakened in an earlier grow七h−stage and it disappears rather gradually．

CoLuGNoN reckoned七he upward shif七〇f the umbilical tubercles with growth as

asubgeneric character． This is， in my opinion， not so significant， since a similar feature is discernible in some examples of Bαγγo緬6θγα8（s．s．）． Other species which I am going to refer to．Bα88θ06θγα8 do not necessarily show this character．

In the reduced ornamentation Bα88θoeθγαs is similar七〇SoIgθγifθs REEslDE，

1932．In this connexion some remarks should be given on the latter genus．

801gθγπθ8 was established by REEsIDE（1932， p．14）as a subgenus of Bαγ一 γ068Z6θγα8 for the group of B．扮αη￠oゼSoLGER，1904． As the specimens of B．bγα竹coZ are no七accessible to me， I have to depend on REYMENT，s revision

（1958，p．65）a8 well as SoLGER s original description（1904， p．174， p1．5， figs．4，

5）to understand what B． bγαη￠oゼreally is． Unfortunately the best preserved syntype（No． I specimen of SoLGER，1904， pl．5，丘g．4；reproduced in the野θατゼ8θ，

fig．551−1）is missing． According to REYMENT， as well as SoLGER， No． III speci−

men is identical with No． I and No． II． Then i七follows that B．6γαη60τevidently

has weak mediolateral tubercles on the immature whorls． Until I could look

at SoLGER s specimens and／or a good collection of a population from the七ype−

locality， I should follow REYMENT s observa七ion．

80Zgθγ批8 in this sense is probably a derivative of a compressed subgroup of．Fo θ8曳がα， with attenua七ion of the orllament．801gθが￠θ8 should， thus， be separated from Bαγγoτ8 ￠θγα8 as a distinct genus． In other words， Bα88θ06θγα8 and 801gθγ τθ8 are probably superficially resembling， parallel developments in the Barroisiceratinae．

As WRIGHT（1957， p． L432）has pointed out， P初θτθαμooθγα8 BAssE，1947，

falls in the synonym of 80Zgθ励θ80f the above interpretation， because its type−

species， P初θ￠θαμ06θγα8θboγoθη8θBAssE， likewise has small mediolateral tuber−

cles on the inner whorls， as BAssE（1947， p．143）herself clearly described and as REYMENT（1954， p．265）discussed． Minor differences in the shell−form， um−

bilical margin， pattern of sutures， etc． would not deserve good criteria to distinguish the two nominal genera．

In 801gθγ屹8 bγαη￠oづthe umbilical tubercles are weak even in the immature stage and almo8t absent in the main stages， whereas the outer half of the ribs and also the ventrolateral tubercles persist to a later stage． In Bαγγoτ8τ6θγα8

（Bα88θo￠θγα8）60Z￠耽αpゼ， on the contrary， the umbilical tubercles are fairly

＊The plaster cast of the llolotype of B．60Z6αηα餌was kindly sent to me through Dr．

J．SORNAY．

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strong in the immature stages and evidently persist to a Iater stage than in 8．bγαηco乞． This can be taken as one of the generic criteria． In this respect，

Bαγγo 8i6θγα8γowτiθ秘出Z PERVINQuERE（1907， P．383， pl．12， fig．12；text−fig．104），

from Tunisia， is prol）ably referable七〇Solgθγ乞￡θ8， although its inner whorls have not been satisfactorily examined．

When the above interpretation of 80膓gθ碗θ8 is accepted， some of七he species which were previously referred to 801gγ党θ8 should be七ter be replaced to Bαγγoτs乞一

￠θγα8 （Bα88θ06θγα8）． For instance， Solgθγ乞τθ8607zgoθ？zsi8 BAssE （1947， p．125）

［＝Bαγγoゼ8icθγα8んα6θγ∫θ励θγτ， LoMBARD，1931， P．298， pl．31］， from the Coniacian of Congo， is either an example of Bα88θocθγαs or a七1east an intermediate form from Bαγγoi8Z6θγα8（Bα oゼ8Z6￠γα8）七〇B．（Bα88θooθγα8）．

The species from the Celendin Formation（Bμ￠厄cθγα8 bZZobαfμ蹴zone）of Peru， described under Bαγoi8乞cθγαs（Solgθγ飽8）bγαηco乞by BENAvlDEs−CAcEREs

（ユ956，p．477， pl．58， figs．1−4）is another example of Bα88θ06eγαs． A new specific name， Bαrrojsjcθrαs（Bα88θocerαs）pθrωujαημ7ηsp． nov．， is proposed here for it．

The species is established on two specimens， A． M． N． H． No．27887／1（holtoype）

and 2（paratype）． It is distinguished from 80Zgθγπθ8 bγαη￠oZ by the coarser and stronger ribs， more dis七inct umbilical tubercles and the absence of medio−

lateral七ubercles on its inner whorls． It has a more compressed and more involute shell， with a higher roof−shaped venter， and more numerous and more slender umbilical tubercles than BαγγoZ8乞6θ？・α8 （Bα88θocθγα8）￠ol￠αηαpZ（CoI．LIGNoN）．

Even in the smoothish outer whorl B．（Bα88eo6θγα8）pθγ伽Zαημ仇is distinct in

its very high and compressed section and persistency of七he fastigate venter．

Therefore， it is somewhat similar七〇Hαγ1碗Zθ8 in shell−form， but i七has no mediolateral tubercles and i七s ventrolateral clavi are no七so persistent and its suture is not so reduced as in正1αγ1θ e8．

Incidentally the illustra七ed specimen of U〕THY （1918， p．48， p1．4，且g．1）

under 86んloθηbα6〃乞α（Bαγγo乞8乞cθγα8）恒αη606 var．勿砺8 SoLGER， which has weak mediolateral tubercles on the 6ne ribs， cannot be identified with B．（Bα88θ06θγα8）

pθγ耽乞α拠批here de6ned， but is probably an example of true Solgθ働θ8 from Peru．

801gθγπθ8￠z功θγ仇Zα￠秘8 REYMENT（1954， p．267， pl．2；text−fig．11；1955， p1．17，

6g．5）， from the Coniacian of Nigeria， is again another example of B．（Bα88θo−

cθγα8），because it has no mediolateral tubercles and is very similar to species of Bαγγoゼ8乞6θγα8 in the stages preceding to the smooth last s七age．

Bαγγoτsぜ￠θγα8（Bα88θooθγα8）仇oγηα九勿sp． nov．

P1．39 ［27］，Fig．1；Text−figs．3−4

丑oloε卯θ．−GK． H5460， from the zone of 1πocθγαmμ8μτoαグ拠θη8乞8， Pombets Gono−sawa（Coll． T． MuRA］MoTo， P5−6234）．

1レfθαsτLγθγη杉γz亡s．一

GK． H5460

〃（−160°）

Diameter

80．0（1）

54．5（1）

UmbiliCUS

12．8（．16）

8．5（．15）

Height

40．5（．51）

31．5（．58）

Breadth

24．6（．31）

21．4（．39）

B．／H．

．60 ．68

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．ψ

弘，，

v．グ

∂

〃

20mm

q

−

Fig．3． Bαrγo元sτ6θγ1α8（Bα88θooθγ唱α8）カτoγγλα￠祝？ηsp． nov．

b

GK． H5460， holotype． Diagrammatic sketches of lateral（a）and frontal

（b）views．（T． M．∂θ励．）

∪3（rS）

︶

L ε

5rnm

Fig．4． Bα㌍㌍oτsτ￠θγα8（Bα8sθooθγα8）力己oγワzαれ￠γ7z sp． nov．

GK． H5460， holotype． External sutures at whorl−height＝25 mm．

（T．M． dθ1τγτ．）

1） αgη08ぜ8．−The shell is rather small， Iess than 100 mm． in the diameter of the adult stage， involute and narrowly umbilicate． The whorl is considerably higher than broad， showing about 10：6＿7 in the proportion of height to breadth，

and broadest in the lower part（i．e． near the umbilical shoulder）． The umbilical

wall is overhanging and the umbilical shoulder is subangular． The flanks are

slightly convex and convergent． There are obtusely subangular ventrolateral

shoulders；七he ven七er is narrow and roof−shaped with a Iow median keel． The keel and the ventrolateral shoulders are weekened but remain in the main part of the body−whorl． In the final part of the body． whorl the keel is almost lost and the venter is gently arched．

(10)

The surface of the body−whorl is nearly smooth， except for the prorsiradiate lirae on the flank， faint serration on the week keel on its posterior half and a few， occasional， blunt， remnants of ribs and umbilical bullae． In the preceding stage， i．e． on the main part of the septate whorls there are sparse umbilical

bullae， faint ventrolateral clavi and fairly distinct medioventral clavi which correspond in number to the ventrolateral ones． No mediolateral tubercles are

discernible． The orllaments of earlier whorls are concealed in the holotype．

The suture in the adult stage is deeply and fairly finely incised． Especially the 6rst lateral lobe （L） is so deep that it is overlapPed by a part of the saddle of the immediately preceding suture（see Fig．4）． The sutural pattern is some−

what peculiar． The丘rst lateral saddle（between E and L）is subrectangular in

rough outline， apParently tripartite， having a very deep， vertical lobule on七he inner side （i．e． closer to L）． The first lateral Iobe （L）is the deepest， sul）−

rec七angular in rough outline， divided into several deep branches in the lower part by narrow， upright， folioles of dissimilar heights． The second la七eral saddle

（between L alld U2）is again irregularly tripartite， having a deeper lobule on the outer side（i．e． closer to L）． The auxiliaries are gellerally descending， but the lobule at the umbilical shoulder is unusually small． Finely subdivided folioles

show somewhat phylloid terminals in some parts．

Rθ仇α励8．−Only a single specimen is available at present， but its observed characters are so diagnostic that it is regarded as representing a new species．

Co糀忽αγτ80η．−The present species is distinguished from Bαγγo乞8乞6θγα8

（Bα88θo￠θγα8）￠oZcαηαpづCo肌IGNoN（1965， p．74， pl．447，血g．1826）， from the Coniacian（zone of Pがoηo￠〃cZo6θγα8 gWαbα％μ働）of Madagascar in its more compressed whorls（b／h＝0．6＿0．7 as compared with O．8（十）of．8． oolcαηα餌），

smaller umbilicus（u／d＝0．16 as compared with O．260f B． col6耽αp乞）， finer ventrolateral clavi and weaker and bullate umbilical tubercles which do not shift upward on the outer whorl．

BAssE （1947）6nely demonstrated the great variability of BαγγoτsZcθγαs

o捌α吻θη8θBAssE， in which ornaments sometimes tend to become weak and delicate． It is noted that the described specimen from Hokkaido somewhat

resembles one of the illustrated specimens of B． oηZIα吻θη8θBAssE（1947， pl．4，

6g．2），although the former has more compressed whorls and still more weakened or nearly obsolete ornaments． The resemblance suggests that the present species could be derived from a certain species of BαγγoZsZcθγα8（BαγγoZ8Z6θゲα8）by

weakening of ornaments and by compression of whorls． The difference in the

pattern of sutures between the two species is considerable， but the great varia−

bility in sutures of Bαγγo乞8Z6θγ・α8 as illustrated by BAssE seems七〇imply that such a particular pattern of 8uture as the present species could be led from a Hexible suture of Bαゲγoi8乞6θγα8 （s．s．）．

The present species is super丘cially similar to．P初θ￠θαμocθγα8θboγoθη8θ BAssE（1947， p．142， pl．33［9］，丘gs．4，5），from the Coniacian（ Eboro bed ）of Madagascar， in the shell−form， generally smoothish surface， and mode of the ventral ornament8． The Eboro species， which should be referred to Solgθ励θ8 as discussed above， is provided with small mediolateral tubercles in a certain

(11)

growth−stages． B．（Bα88θ06θγα8）仇o推α￡μ伽has no mediolateral tubercles and more compressed whorls． Its suture is distinct from 80Zgθγ伽8θboγoθη8乞8 in the Iong， narrow and upright folioles and lobules of L and adjacen七saddles．

B．（Bα88θo￠θγα8）仇oγηα枷物resembles Solgθ働θ8（？）1αθ励8 BAssE（1947，

p．125，pl．15［9］，6g．1；text−fig．4）， from the Coniacian （ Eboro bed，，）of Madagascar， in the smoothish and compressed shell． The two species are similar in the general pattern of suture， but differ in details as can be understood by comparing the text一負gures． The umbilical margin is subangular and overhanging

in the Hokkaido species， but it is rounded in the Madagascar species． The

ventral keel and the ventrolateral angulations are weakened but persist to the posterior part of the body−whorl in the former， whereas they disappear earlier and the venter is more rounded in the latter． Incidentally，80ZgθγZεθ8（？）1αθ励8 BAssE may be referable to Bα88θocθγα8．

The descril）ed holotype of Bαγγo 8Z6θγα8（Bα88θ06θγα8）仇o推αZz棚shows an

interesting feature that the body−whorl七ends to become less involute， with

widened umbilicus， and to be slightly decreased in height at七he Iast stage．

This scaphitoid character cannot be overlooked as accidental， since a similar

feature is observable in some species of 8εol㌘んα α（see SpATH，1931， p．328），

刀Zα励θIIZ6θγα8（see MATsuMoTo et al．，1969， P．253 and p．258）， and Afθ加 cooθγα8

（see HYATT，1903， pl．13， fig．4；pl．14， fig．7；CoBBAN，1953， pl．9）， as well as inτθκα8Zα（see WRIGHT，1957， p． L432）．

06￠視γγθη6θ．−Gono−sawa（i．e． the 6fth tributary）of the Pombets， a branch

of the Ikushumbets， central Hokkaido． The described specimen was found by T．MuRAMoTo in a calcareous nodule of greenish dark grey， sandy siltstone，

along with numerous specimens of 1πocθγα仇μ8秘ωαグ碗θη8Z8． The age is， accord−

ingly， Lower Urakawan， apProximately Coniacian．

Genus Foηθ8彦．θ冗αREEsIDE，1932

8鋼o吻物〃．−CoZZZgητoη乞6θγα8 vAN HoEPEN， 1955 ⑰oη ColZ乞9ηo励cθγα8

BREIsTROFFER，1947）；CoZI乞9ηoηθZIαVAN HOEPEN，1957．

τ〃pθ一8pθoZθ8．−BαγγoZoZ8θゲα8（Fo θ8舌θγZα）∫oγγθ8τθがREEslDE，1932（original designation）［＝170γγθ8τθηααIZμαzL（Zτ（BouLE， LEMoINE and THEvENIN，1907），as described below］．

GθηθγZ6砺αg％08 8．−The shell is typically moderate in size， about 80 to 100mm． in diameter at the adult stage， but larger in some species and smaller in others．

The involution is moderate；the umbilicus is typically 25±5 percent of the shell diameter， but may be of variable width． The whorl is nearly as high as broad， or more or Iess broader than high， or勿乞6θ勿θγ8α， being fairly variable in section． The ventral keel is dis七inct．

The omament is typically strong． It consists fundamental of rectiradiate ribs， with intercalation or bifurcation of the shorter ones at about the middle of the flank， umbilical， mediolateral， ventrolateral and medioventral tubercles．

The tubercles are generally strong． Especially the mediolateral ones are

(12)

prominent in the middle growth−stages． The umbilical tubercles may be some−

times weaker or indistinct． The ornamellt may be modi6ed in various ways，

giving distinction between subgenera or species groups．

The suture has rather massive lateral saddles on both sides of rather

narrow L and is moderately indented， but may be variable in minor details．

Rθ伽α袖s．一、Poγγθ8亡θがαwas established by REEsIDE as a subgenus of Bαγ一夕o乞8ぜ6θγα8，together with subgenera Tθ鋤8τα， AZ8εαdθ励古θ8 and五rαγZθπθ8． I agree

with REYMENT（1955）and WRIGHT（1957）in regarding 170γγθ8亡捌αas distinc七

from Bαγγoi8Zcθγα80n account of the presence of prominent mediolateral tuber−

cles in at least early to middle growth−stages． It is a fairly comprehensive and variable genus， comprising at leas七七hree subgenera， i．e． Foγγθs￠θ万α （s．s．），

Rθθ8掘θ06θγα8BAssE，1947， and a new one（1∬ZLγαγη0τ0α）to be established below．

Z祝？ηPαγzgo6θγ・α8 BAssE，1947， could also be included in 1アoγγθ8τθ仇αas a subgenus，

but I have no positive comments on this subgenus， which was established on crushed specimens from the Coniacian of Mexico（BuRcKHARDT，1919， pp．99−

108；pl．22， fig．16；pl．23， figs．1−2；pls．24 and 25）． I should furthermore in−

clude E（1θη06θγα8 vAN HoEpEN，1968（with type−species E．阻μ1比os￡α加仇vAN HoEPEN，1968）in Foγγθ8￠θγ乞αas a subgenus．

Hαγ1θ乞εθ8REEsIDE，1932， with which AI8￠α∂例伽s REEslDE，1932， is syno−

nymous（WRIGHT，1957， p． L434；BAssE，1947， p．137）， is treated in this paper as an independent genus for the reasons described in another page （see genus

Hαγ1θ乞τθ8）．

The type−species of Foγγθ8￡θγZα， F．∫oγγθ8τθγZ REEsIDE，1932， is identical with ∠46α励んocθγα8 （PγZOη0加0廊） α1伽αμd冤BoULE， LEMoINE and THEVENIN，

1907，as is discussed below． VAN HoEPEN（1955， P．361）established Colligηo励一 cθγα80n the type−species C．んα抗抗θγ81θψvAN HoEPEN，1955． This generic name was subsequently renamed by vAN HoEpEN（1957）as CoZ吻πoηθIIα， as he noticed that Coll gηo励cθγαs vAN HoEpEN，1955， is a homonym of and preoccupied by Co膓1乞9ηo励oθγα8 BREIsTRoFFER，1947． Co〜ZZgηoηθIZαvAN HoEPEN，1957， is， how−

ever， a synonym of Foγγθ8￡θγτα， because C．〃α仇働￠γ81θ班and other species which vAN HoEPEN assigned to Col吻ηoηθZIαare all good examples of Foγγθ8τθ励α， as

vAN HoEPEN（1968）himself has recently acknowledged．

Species of F「oγゲθ8fθ万αoccur in the Coniacian of various regions， some of

which show world−wide distribution．

Subgenus Foγγθ8￠θ弼αREEsIDE，1932

1〜θ仇α袖s．−F「．（F．）αIZ％αzL碗（BouLE，1・EMoINE and THEvENIN）， the type−

species， represents generalized or average characters of Foγγθ8￡θがα， showing

蛤ther a gradual change of ornament with growth． More depressed and strongly

七uberculate species as 1汀．γαzαガ励Pαγαη糎Col・1・IGNoN，1965， and F． rθ〃働θ励づVAN

HoEpEN，1968（the two of which are closely allied to each other and could be

identical）， are included in 170γγθ8Zθγτα （s．s．）．

In F．んobso励（REEsIDE，1932）the mediolateral tubercle is shifted upward

and united with the large， horn−like ventrolateral tubercle on the adult whorl．

(13)

Iwould regard this charac七er as specific rather than generic， since such a feature does not necessarily occur in other species of Foγγθ8君θγZα．

The subgenus、Foγγθ8￡θγZαcomprises also less depressed but distinctly tuber−

culate species， such as、P．伽θbαθvAN HoEPEN，1968， and a new one（F「．αγ7ηατα）

to be described below．

The illustrated syntype of GαzL彦〃 θγ 6θγα8γηαγ9αθ var． Z）θγτ↓αγzμγ7z BRUGGEN

（1910，p．720， pl．27，6g．3）and the 6nely illustrated specimen of L、むTHY（1918，

p．41，pl．1，6g．2）， from the Coniacian of Peru， probably represent another

species of rather compressed Foγγθ8τθ冗α， as is F．（17．）bα88θαθBENAvIDEs−

CAcEREs（1956， p．477， pl．58， fig．5）． They seem to be identical and should be

called Foγγθ8舌θ？イα （Floγγθ8τθηα）Pθγμαγ梛伽（1効GGEN）．

Some of the less depressed species such as 17．8亡α批o励（REEsIDE，1932）and F．ρπα1θη8乞8（STEINMANN，1897），11ave a modified ornament on the outer whorl，

on which mediolateral tubercles are absorbed by raised ribs． This subgroup can be， in my opinion， grouped with the subgenus E∂梛ooθγα8， because on the outer whorl of E．勿％IZτ608fα九物vAN HoEPEN（1986， P．171， pl．12， text−fig．4b）， the mediolateral and also the umbilica1七ubercles are likewise absorbed by thick ribs．

Secondary， shorter ribs are more frequently intercalated in E．物視1飽08Zα加祝，

but this is probably a specific character．

The subgenus IZθθ8 d！θooθグαs BAssE，1947， has Iess infla七ed flanks and its mediolateral tubercles fuses with the umbilical one oll the outer whorl． Its type−

species is∠Lηz伽o？zπθ8 Pθ￠γ060冗θγz8乞8 CoQuAND （1859， P．995；DE GRossouvRE，

1894，p1．2， fig．5）． Rθθ8乞∂θ06θγα8 gαIIZcτ〃7z BAssE，1947， is an unnecessary specific name， because it is synonymous with Foγγθ8￠θγZα（Rθθ8掘θo￠θγα8）Pθ亡γocoγ乞θη8 8．

In this subgenus the keel disappears on the outer whorl， on which七he venter is flat or concave， bordered by ventrolateral clavi．

The world−wide species F．（F．）αZZμα閲ゼis found in Hokkaido． In addition to it there is another remarkable new species of Foγγθ8￠θγZα（s．s．）in the collec−

tions from Hokkaido．

No examples of、Foγγθ8￠eγZα （Rθθ8Z∂θocθγα8）and F．（E∂θη06θγα8）have been found in Hokkaido， but there are two species of a new subgenus， which are characterized by a smoothed outer whorl．

Foγγes亡θ働（1汀0γγ￠8亡θ甑）α1玩α砿乞

（BOULE，1・EMOINE and THEVENIN，1907）

Pl．40 ［28］， Figs．1−4；Text−figs．5−7

1907．

1908．

1910．

1932．

A￠α励ん06θγα8 （Pηoηo￠γoが8） αZZμαz￠砺 BouLE， LEMoINE and THEvENIN，

／1γzγz．PαZεo？zε．， vo1．2， P．12 ［32］， pl．1 ［8］，6gs．6，6a，7， text−69．17．

P励oγ↓oぴoが8α1抗αμ（ガ，LISsoN， Sobγθαlg祝η08醐伽πo痂亡θ8（1θZ Pθγz↓， P．17，

pl．17．

Pγτoηoγo傾8αZZτLαzL砺， BR廿GGEN，2V．」．ハZ仇． BθゼZ． Bd．30， p．772．

Bα勿γoi8τ￠θγα8（Fo θ8Zθγiα）αIZαμ碗［8司，REESIDE， U． S． GθoZ． S蹴η． Pγo∫．

Pαρθγ170−B，p．14．

BαγγoZ8τ￠θγα8 （Foγグθ8￠θ万α）∫oγγθ8舌θηREESIDE，σ．8． GθoZ． Sμγ〃． Pγo∫．

Pαpθ170−B，p．17， p1．5， figs．2−7．

(14)

1947．

？1955．

1956．

1965．

Bαγγoゼ8乞cθγα8 （F「0γγθ8￠θγτα）αZZμαμ（li， BAssE，∠4γτγτ． Pα160ηム， vol．33， p．128

［32］，pl．8，6g．3，3a；pl．9， fig．2，2a （？）．

CoZI汐ηo痂cθγα8 Pθ7心θ9γiηαεoγvAN HoEPEN， So励んAρ． Jo耽． S6τ．， Vo1．51，

p．364，text−figs．10−11．

Bαγγoi8τcθγα8 （F・oγγ、θ8￠θγiα） αZZ視ατLd冤， BENAvIDEs−C五cREREs， BμII ノ1仇θγ 1μμ8．Nα￠． Hτ8亡．， vol．108， P．478， P1．61， fig．1．

Foγγθ8亡θ冗α αIZ視α視（江， CoLLIGNoN，1965， A￠1α8 Fo88τ1θ8 Cαγα6￠θγ． Mα∂α一 gα8cαγ， fasc．13， p．76， p1．448， fig．1828．

10mm

一

⁵

「

︐︑︵

｝ 10mm

一

70

、≡＿ノ

人）

＼，ノ6 ．ノ㌃＝ 7b

Figs．5−7． Foγγθ8￠θパα（Fo宵θ8￠θ万α）αIZz↓肌6砺（BouLE， LEMoINE and THEVENIN）．

Whor1−sections in various growth−stage．s and an e．xternal suture of an immature shell．5：GI（． H5442，6：GI（． H5440，

7：GK． H5441b．（T． M．∂θ1仇．）

丁脚θs．−BouLE et al．（1907）did not designate the holotype． Of the two illustrated syntypes， the larger one（BouLE et al．，1907， pl．1， fig．6，6a）is some−

what malformed in that the ventral row of tubercles deviates from the siphonaI Iine． The smaller one（BouLE et al．，1907， pl．1， fig．7；七ext一盒g．17）may be be七ter preserved， but the authors did not illustrate its side view． Therefore，

Ihesitate to designate the lectotype without seeing the specimens， although

they are certainly of identical species．

Mαεθγ乞α1．−The following six specimens from the Ikushumbets area are

referred七〇this species：（1）GK． H5442（T． MuRAMoTo Coll．2156），from Gono−

sawa， Pombets，（2）GK． H5440（T． MuRAMoTo Col1．914）， from a pebble of the

Ikushumbets at Yayoi，（3）GK． H5441（T． MuRAMoTo Coll．）， from another pebble of the Ikushumbets at Yayoi，（4）GK． H5464（T． MuRAMoTo Coll． P5−

2451），from Gono−sawa， Pombets，（5）GK． H5622 （H． KoKuBu Coll．）， from

Ik 2119 p， Gono−sawa Pombets， and（6）GK． H5623（T． TAKAHAsHI Coll．36613），

from Ik 2147 p， Gono−sawa， Pombets．

Spθ￠碗￠砺αgη08Z8．−A species of 170γγθ8亡θがα（s．s．）which has a moderately stout shell， moderately distant and coarse， radial ribs， and distinct tubercles，

of which the mediolateral ones are the most prominent． Sutures are moderately

(15)

incised， having Iateral narrOW lateral lObeS．

saddles of roughly subrectangular outline and fairly

1レfθα8ZLγθγηθγ乙診8．一

Specimen

GK． H5622（c）

一^{（十10°）（ic）}

一^{（−180°）（c）}

一（−190°）（ic）

GK． H5623（c）

一^{（−10°）（ic）}

一^{（−180°）（c）}

一（−190°）（ic）

GK． H5440（c）

一^{（＋10°）（ic）}

GK．且5442（c）

COLLIGNON，

1965，p．76

Diameter Umbilicus

40．5（1）

23．7（1）

22．4（1）

29．0（1）

〜57 81

9．2（．23）

5．6（．23）

5．2（．23）

8．2（．28）

〜16（．28）

25（．31）

Height

20．4（．50）

20．0（．49）

13．5 12．7 11．7（．49）

11．2（．50）

7．2 6．6 12．8（．44）

11．8

〜27（．48）

37（．46）

Breadth BりH．

25．0（．61）

22．0（．54）

17．3 13．0 13．8（．58）

11．2（．50）

7．2 6．3 17．06（．58）

14．0

1．22 1．10 1．28 1．02 1．17 1．00 1．00 0．95 9一∩δ0 0_1⊥

コ

寸⊥噌⊥

〜33（．58）〜1．2

50（．62） 1．35

Number of

major ribs per whorI

11

12

50r 6×2

14（15？）

For comparison

F．∫o θ8舌θ碗

（REEgIDE，

1932，p．17）

the same

（p1．5， f．2−4）

C．Pθγθ9γ仇αεoγ

（HOEPEN，1955，

p．364）

〜50（c）

〜50（ic）

28（c）

14

26．5（c）

（ic）

75（1）

（ 1／4−1／3，，）

5．9（．22）

20（．27）

25（．5）

13（．46）

6（．43）

13（．49）

13

36（．48）

33（．6）

25（．5）

16（．57）

4．5（．32）

ρO

ピ0

1⊥ ・

3 1

45（．60）

1．2 1．0 1．2 0．75

4

9一ハU

コ寸⊥︷⊥

1．25

10（？）

10

11（？）

Z）θ8励p励θγθ勿α祐8．−The specimens from Hokkaido show characters of

various growth−stages． GI（．且5442 is nearly as large as the large syntype of BouLE et al．， while GK． H5622 is slightly larger than their smaller syntype and slightly smaller than BAssE，s（1947， pl．14［8］，毎．3）specimen． GI（． H5623 is

asmall shell， representing the stage immediately preceding七〇tha七〇f GK．

H5622． Other three specimens are as Iarge as one of七he above three and show apart of still inner whorls， although they are more or Iess defective． The speci−

men illustrated by CoLLIGNoN（1965， pl．448，丘g．1828）is七he Iargest but still wholly septate． One of BRUGGEN s（1910， p．722）specimens， from Peru， seems

to be as Iarge as Co肌IGNoN s from Madagascar， although I have not seen it．

No example as large as C旺LIGNo．N s has been obtained from Hokkaido， although GI（． H5442， which preserves a portion of the body−whorl， may have been similarly large when it was complete．

Summarizing the observation of these specimens as well as other previously described ones， it may be stated that the present species shows a rather gradual change of characters with growth． The specific diagnosis described above con−

cerns primarily with the shells of later growth−s七ages． There are， furthermore，

minor dif［erences between individuals of the same growth−stage．

(16)

The whorl grows with a moderate rate， embracing a little over a half of the inner one， with the umbilical seam just on the row of mediolateral七ubercles．

The umbilicus is， accordingly， fairly narrow， ranging from one third to one fifth of the diameter of the entire shell． It is considerably deep．

At 6rst the whorl is slightly higher than broad， having distinct ventrolateral shoulders and a keeled venter． A七the shell diameter of 20 mm． or so the whorI becomes broader， being as high as broad in the intercostal section and some−

what broader than high in the costal section（between tubercles）． In the later growth−stages it is slightly broader than high even in the intercostal section

（wi七h b．／h．＝about 1．1）and collsiderably broad in the costal section （with b．／h．＝1．3±0．1）． The intercostal whorl−sec七ion is subrounded， with a steep umbilical wall， a rounded umbilical shoulder， moderately inflated flanks， and an

arched but weakly keeled venter． Owing to the strong七uberculation the costal

whorl−section looks polygonal．

Ribs and tubercles begin to appear at abou七the shell diameter of 10 mm．

In the early stage they are not so strong as in the later stages， especially the umbilical tubercles are undeveloped or indistinct， the mediolateral ones are of modera七e intensity， where ribs are normally bifurcated， and the ventral orna−

ments of the barroisiceratine type， consisting of three rows of clavate tubercles and rib8 in chevrons， are characteristic．

In the later growth−stages the ribs are coarsened and the tubercles are strengthened． The mediolateral七ubercles are especially prominent， having a large

base and a spinose apex． The umbilical tubercles are much smaller and of variable intensity． The ventrolateral tubercles are modera七ely strong， having

abroader base than in the earlier growth−stage． The medioventral clavi persist to the adult stage， although the keel is lowered．

Alow major rib runs radially from the umbilical margin to the mediolateral tubercle． The mode of bifurcation of the ribs at the mediolateral tubercles may vary with individuals or from place to place even in one specimen． Typica11y one secondary rib is projec七ed forward and the other runs almost radially on the extension of the major one． Sometimes Y shaped branching is shown． Occa−

sionally the intercalation of the secondary rib is seen at one place， while the simple extension of the major rib is seen at another．

As far as the measurable specimens are concerned， there are 10 to 12 major ribs in a whorl． GK． H5442 may be exceptional in that its septate whorl has

somewhat more crowded and more numerous（14）ribs， but on its body−whorI

the rib8 are as distant as in normal specimens． On七he other hand the holotype of BαγγoZ866θγα8 （Foγγθ8￠θ仇α） ∫oγ？楡θ8古θγZ REEsIDE （1932， P．17， pl．5，69．2−7），

NSNM．73757， has 10 major ribs per whorl and the ribs on七he outer whorl

seem to be somewhat more distant than those on the syntypes of F．α伽α偏τ．

The dif［erence is by no means great and can well be included within the varia−

tion of．F．（1P．）α批α城Z． As the available specimens from North America are few， it is not decided at this moment whether a subspeci丘c separation is possible

or not be七ween the North American and Madagascar groups of individuals．

It is interesting to note that some of the specimens from Hokkaido（e．g．

(17)

GK． H5442， H5622 and H5623）are closer to the syntypes of、F．（F．）αZIματL（況 from Madagascar and some others（e．g． GK． H5440 and H5441）are rather similar to the holotype of F．∫oγγθ8亡θγ￠from North America． The latter subgroup has

slightly more distan七ribs and better marked umbilical七ubercles in somewhat

earlier growth stage than the former， but the difference is slight and there is gradation between the two subgroups． In other words it is natural and reasonable

七〇refer the Hokkaido specimens to one and七he same species which in itself shows a moderate（but not great）extent of variation．

BENAvlDEs−CAcEREs （1956， P．479）stated that F．αIIμαμ〔IZ and 17．∫oγγθsτθが were separable only by the spinose character of the ornamentation in the latter

species． This is， in my observation， merely a problem of preservation． GK H5622， for instance， does show the spinose mediolateral tubercle on a well

preserved part but the spine is septate and only the basal rounded nodes are

shown on other parts of the same specimen．

Taking all the above observations in七〇consideration， I am led七〇the con−

clusion that Foγθ8亡θγ乞αプoηθ8￠θが（REEsIDE，1932）falls in the synonym of Foγグθ8舌θがαα1ψαμ碗（BouLE，1・EMoINE and THEvENIN，1907）． Even if the sub−

specific separation could be considered， the specific nameα伽α煽Z should precede

∫oゲγθ8￠θγ6．

CoII乞9γzoγzi￠θrα8 pθγθgがηα￠oγvAN 且oEPEN，1955，（p．364， text−figs．10−11），

from South Africa， is possibly identical with F．α1伽α城Z， because of the similarity in every respect． VAN HoEpEN（1968， p．167）has recen七ly regarded

F．PθγθgZ％α加γas iden七ical with、P．んα仇仇θγ8Z￠〃Z vAN HoEPEN，1955． Should this be accepted， then it would follow that the Iarge holotype of F．んα働㎜θγ81θψ

（vAN HoEPEN，1955， p．361， text−6gs．7−9），from Sou七h Africa， with a diameter over 220 mm．， would represent七he fu11−grown stage of 17．α1勧α煽i． I refrain from giving the final conclusion， until I can examine relevant specimens from

South Africa and Madagascar．

Aminor but interesting malformed fea七ure is occasionally observable in

the available specimens． On七he last one third of the whorl of GK． H5623， the

medioventral row of tubercles deviates from the siphonal line， resulting in unequal distance from the row of ventrolateral tubercles on either side． The

same feature is seen on one of the syntypes of Bo肌E et al．（1907， p1．1［8］，

毎．6a）．

Co伽Pαγ 80π．−F oγγθ8￡θηα（Fo御θ8τθγZα）αII祝α2雄most typically represents the sul）genus Foγγθ8τθγταin that it shows the subgeneric characters in a general way and in a moderate degree． It is not so compressed as F．8θ砂iθγθη8θ

（REEsIDE）（1932， p．16， pl．4， figs．4−8）nor is it so depressed as 1汀．γαzαガ厄一 Pαγα？zψCol、ロGNoN（1965， P．78， pl．449， figs．1829−1831）． Its ribs and tubercles

are regularly disposed and rather gradually strengthened with growth． In this

species there is no hypernodosity nor shift of tubercles as in F・んob80？zゼ

（］REEslDE）（1932， P．18， P1．9， figs．1−2， pl．10， figs．1−2）， nor fusing of la七eral tubercles into sharp ribs as in 17．8￠α励o仇（REEsIDE）（1932， p．17， pl．7， figs．

1−7；pl．8，6gs．1 3；pl．9， fig．1）．

(18)

Foγγθ8εθγ乞αcf．αZIα掘乞［sic］of PARNEs（1964， p．23， pl．2， figs．7−8）， from

Israel， which has compressed whorls and somewhat upward shifting lateral

tubercles， is probably distinct from F．α批α掘τ， unless the compression owes to secondary deformation． It may be closer to， if not identical wi七h， Foγγθ8fθγiα bα88θαθ （BENAvlDEs−CAcEREs）（1956， P．477， pl．58， fig．5）［＝Bαγγoぜ8乞cθγα8 んαbθγ∫θZIηθγZ， BRむGGEN，1910，印oηHAuER），P．730， text−fig．10］［＝Bαγo乞88i￠杉γα8 λαbθヅθIIηθγτ， ST．EINMANN，1930， text−fig．195］， from Peru， or、F． Pθ閲α批抗

（B前GGEN），emend．

Foγγθ8亡θγ掘（Foγγθ8亡e万α）わ仇αssαi（VENzo）（1936， P．88， pl．7［3］， fig．12；

text−fig．1）from Zululand， South Africa， closely resembles F，（F．）α批α閲ゼ， but has stronger ribs． In the latter species the tubercles are rather prominent over ribs．

066祝γγθη￠θ．−Gono−sawa， Pombets， a tributary of the Ikushumbets， zone of 加ocθγα仇祝8祝ωα元伽θη8乞8；pebbles of the main course of the Ikushumbets， at Yayoi， together with 1ηocεγα仇μ8〃o〃o〃α仇α乞NAGAo and MATsuMoTo． Summariz−

ing these records of occurrence in central Hokkaido， the species seems to occur

in the main or middle part of the Lower Urakawan［＝approximately Coniacian］

in the Japanese scale．

Foγγθ8亡θγ乞α（、Foγγθ8εθγ乞α）αZ抗α癩乞seems to show a world−wide distribution in the Coniacian， since there are available records of its occurrence in Madagas−

car， South Africa， Peru， Utah（U．S．A．）and Japan． In Madagascar， according to Col．LIGNoN （1965）， it occurs in the zone ofκ088祝αε乞￠θγα8 仇θobα1〔1乞α？z視仇一 BαγγoZ8τcθγα8 0励Zα々θη8θ， Middle Coniacian． In South Africa vAN HoEPEN reported the occurrence of 、P． pθγθgγ仇αfoγ from his 1）θγoη乞￠θγα8 beds

（Coniacian）．

Foγγθ8￠θγZα （Foγγθ8￠θγ乞α） αクη7ταεα sp． nov．

Pl．41［29］，Fig．1；Text−fig．8

Holo切pθ．−GK． H5621， from loc． Ik 2144p， Gono−sawa， Pombets（Coll． T．

TAKAHAsHI 42−10−1−1）．

Spθc頒c∂乞αgη08τ8．−A species of Foγγ・θ8εθγ乞α（．Foγγθ8εθ万α）which has com−

paratively higher whorls， less inflated flanks， rather prorsiradiate ribs and

prominent mediolateral tubercles． The umbilical tubercles are indistinct and the ventral ones are of moderate intensity． On the body−whorl the ribs are much

separated and the mediolateral tubercles become bullate and sharp−headed． The

first lateral lol）e of the adult suture is narrow and deep．

1レfθα8τLγθγηθγzτ8．一

GK． H5621 at the last septum（ic）

behind （c）

Diameter

82．0（1）

一

UmbiliCUS

24．6（．30）

Height

40．0（．49）

34．2

Breadth

26．0（．32）

33．6

B．／H．

←

08

n

bOV

●

■

Dθ8cγ⑳物θγθ仇αγ〃8．−Only a single specimen is before me whorl is crushed， but the observable characters are distinct．

and its body一

A Monograph of the Collignoniceratidae fromHokkaido Part Ⅲ : Studies of the CretaceousAmmonites from Hokkaido and Saghalien-XX

Kyushu University Institutional Repository