l SSj\)UU31 -ULU4Transactions and Proceedingsof thePalaeontological Society of Japan
New SeriesNo. 116

Palaeontological Society of Japan
December 30, 1979

Co-Editors
Associate editor

I taru HAY AMI and Tsunemasa SAITO
Tomowo OZAWA

Officers for 1979-1980

President: Tetsuro HANAI
Councillors:

Kazuo ASAMA, Kiyotaka CHINZEI, Takashi HAMADA, Tetsuro HANAI,

Itaru HAYAMI, Hisayoshi IGO, Kametoshi KANMERA, Tamio KOTAKA, Tatsuro MATSUMOTO, Ikuwo OBATA, Tsunemasa SAITO, Tsugio SHUTO, Yokichi
TAKAYANAGI, Toshimasa TANAI, Ryuzo TORIYAMA
Members of Standing Committee:

Kazuo ASAMA (Finance), Kiyotaka CHINZEI(General Affairs), Takashi HAMADA (Planning), Itaru HAY AMI (Transactions),
Hisayoshi IGO (Foreign Affairs), Iku wo OBATA (Membership), Tsunemasa
SAITO (Transactions), Tsugio SHUTO (Special Papers), Yokichi TAKA YANAGI("Fossils")
Secretaries:

Hiromichi HIRANO and Yasumitsu KANIE (Membership), Kunihiro ISH I-ZAKI ("Fossils"), Tomowo OZAWA (Transactions), Toshiyuki YAMAGUCHI(General Affairs), juichi YANAGIDA and Ienori FUJIYAMA (Special Papers)
Auditor:

Sumio SAKAGAMI

The fossil on the cover is Nipponitella explicata HANZAWA, an aberrant
uncoiled fusulinacean from the Lower Permian Sakamotozawa Formation,southern Kitakami, Northeast japan.

All communications relating to this journal should be addressed to the
PALAEONTOLOGICAL SOCIETY OF JAPAN,
c/o Business Center for Academic Societies,
Yayoi 2-4-16, Bunkyo-ku, Tokyo 113, Japan.
Sole agent:

University of Tokyo Press, Hongo 7-3-1, Tokyo, japan.

Trans. Proc. Palaeont. Soc. japan, N. S., No. 116, pp. 175-178, pI. 24, December 30, 1979

708.

KIDOA, EINE NEUE DIATOMEEN-GATTUNG AUS DEN
OBERNEOGENEN KOITOI SCHICHTEN,TENPOKU, HOKKAIDO*SEIICHI KOMURA

japan Petroleum Exploration Co., Ltd. (JAPEX), Chiyoda-ku, Tokyo 100

Abstract. Kidoa graviarmata, n. gen., n. sp. (araphid diatom) is described from the
Koitoi Formation (Upper Neogene) in the Tenpoku district, japan.

Systematische Beschreibung

Einleitung
Ordnung Pennales SCHUTT, 1896
Bei der Untersuchung der marinen
Mikrofossilien aus den neogenen Ablagerungen, die im Nordtenpoku Gebiet
umfangreich verbreitet sind, im Zusammenhang mit der Suche von Erdol und-gas hat der Verfasser eine neue bogenformige Kieselalge, die von den bereitsbekannten Gattungen vollstandig unterschieden werden kann, neulich gefunden.
In dieser Arbeit beschreibt und illustriert der Verfasser die neue Gattung,Kidoa, die zur Familie Fragilariaceae
gehOrt. Viele gut erhaltene Exemplareaus den in den Aufbissen gesammelten
Materialien wurden fur die Diagnose
und Beschreibung der neuen Gattung
und Art verwendet. Alle Exemplare,die in den Praparaten durch Pleurax
eingebetteten wurden, werden im Technischen Institut von JAPEX aufbewahrt.

Familie Fragilariaceae
SCHUTT, 1896
Gattung Kidoa, n. gen.
Namengebung:
Herrn Hideo Kmo,
Direktor von Sakhalin Oil Development
Corporation Co., Ltd. in Verehrung gewidmet.
Typusart: Kidoa graviarmata, n. sp.
Diagnose: Theken in Valvarebene mit
Apikalachse gewolbt, in Gurtelansicht
linear-rechteckig, mit den am Pol stehenden derben Fortsatzen, ohne Zwischenbander und Septen ; Schalen dorsoventral,
mit starker gewolbtem Ruckenrand,
linear-Ianzettlich im UmriB, unsymmetrisch zur Apikalebene, mit randstandige Stacheln undregelmaBig
Streifen ;geordnetentransapikalen
Apikalarea vorhanden aber Zentralarea
fehlend.
Bemerkungen: Die bilaterale Strukturanordnung und das Fehlen des Raphensystems rechtfertigen die Gehorigkeit
dieser neuen Gattung zur Familie
Fragilariaceae. Diese Gattung besitzt* Received May 26, 1978; revised manuscript
received Sept. 11, 1979; read june 18, 1977
at Shizuoka.

175

176

Seiichi KOMURA
142'0

derselben Weise wie die Arten vonCampylosira GRUNOW (vgl. HUSTEDT,
1927-64, S. 128) Cymatosira GRUNOW (vgI.
HUSTEDT, op. cit., S. 123) durch Bildung
der bandformig geschlossenen Kolonien
leben mu.Bte.
Kidoa graviarmata, n. sp.
Tafel 24, Fig. 1-8; Abb. 2, Fig. 1-6

TENPOKU-GEBIET

4S'N --\---}~--t-----

a!===~[=~[
10lorn
Abb. 1. Lage des Fundpunktesvier folgende Eigentiimlichkeiten: 1)
derbe Fortsatze am Pol, 2) dichtstehende
Stacheln am Rande, 3) krammerformiger
Schalenumri.B und 4) kurze Streifen auf
der Oberfiache. Sie besteht im wesentlich
in nachster Verwandtschaft mit derGattung Campylosira, die drei erstere
Charakteristiken besitzt und sich vonihr durch die regelma.Big punktierte
Ornamente unterscheidet.
Aus Analogie mit den ahnlichen
Genera mit Fortsatzen und Stacheln la.Bt
sich vermuten, da.B die lebende Zelle in

Namengebung: gravis (lateinisch, adv.)=wichtig+armo (lat.)=bewaffnen, nachden durch viererlei Strukturelementen
ganz ausgeriisteten Theken.
Holotypus: Praparat Nr. JAPEX Fo11(34)= 14.1 X 78.5(Fm15636, 15635, 15634),
Taf. 24, Fig. 1, Abb. 2, Fig. l.
Paratypen: Praparat Nr. JAPEX Fo11(31)= 18.3 X 90.3(Fm15630, 15631), Taf. 24,
Fig. 2, Abb. 2, Fig. 2; Praparat Nr. JAPEX
Fo-11 (23) = 19.0 X 90.2 (Fm 15645, 15644),
Taf. 24, Fig. 3, Abb. 2, Fig. 6; Praparat
Nr. JAPE X Fo-11(25)=13.2X89.8(Fm15642,
15640), Taf. 24, Fig. 4; Praparat Nr.
JAPEX Fo-11(14)=8.6x86.0 (Fm 15628),
Taf. 24, Fig. 5; Praparat Nr. JAPEX
Fo-11(34)=7.2x92.9(Fm15633,15632), Taf.
24, Fig. 6; Praparat Nr. JAPEX Fo-11(40)=9.1x83.0(Fm15626), Taf. 24, Fig. 7, Abb.
2, Fig. 3; Praparat Nr. JAPEX Fo-11(70)=5.3x 132.0 (Fm 16958), Abb.2, Fig. 4;
Praparat Nr. JAPEX Fo-11(68)=1l.0x
138.3(Fm16988), Abb. 2, Fig. 5.
Material: 10 Exemplare.
Typusfundort: Fo-11, Bodenaufschlu.B(Abb. 1), etwa 3,8 km siidostlich vonToyotomi (Breitengrad 45'5'14/1N, Langengrad 141'19'17/10).
Typusschichten: Aschenreicher Kieselgur der Koitoi-Schichten, Oberstmiozan(vgl. MINATO et aI., 1956; NAGAO, 1960).
Beschreibung: Theken in Giirtelansicht
eng-linear, mit gro.Ben derben pedalahnlichen an den Polen stehenden Fortsatzen, die in der schragen Valvarlage

708.

Kidoa, eine neue Diatomeen-Gattung

daher etwas konvergent, tiber die ganze
Oberflache auBer dem hyaIinen Apikalfeld
verbreitet, von Pseudoraphe unterbrochen,
8-9 in 10 f1-; Axialarea oder Pseudoraphesehr eng, fadenahnIich jedoch deutIich,in der MitteIIinie verIaufend.
Bemerkungen : Die vorIiegende Art
zeigt eine bedeutende RegelmaBigkeit
und Einheitlichkeit in der Anordnung
der Streifen und StacheIn, wie die mikrophotographischen Aufnahmen (Taf. 24,
Fig. 5 und 7) deutlich zeigen. Sie tritt
selten oder zwar meistens als Bruchstiickin den Tenpoku-MateriaIien auf, abersie kann durch ihre bogenfOrmigen
SchaIen mit den unnachahmIichen
StacheIn leicht aufgefunden werden.

DO.

0'"
0<0

om

~~

f

177

om
om
DO

Do
Do
Do
DO
DO
DO

o

Danksagung
2Abb. 2.

3

4b

5

6

Kidoa graviarmata, n. sp.

best sichtbar sind und in der Giirtellage
als ungebuckelte Schragflache erscheinen(Taf. 24, Fig. 7 u. Abb. 2, Fig. 4b);
Schalen verlangert, eng-linear bis linearIanzettlich, dorsoventral, gegen den
PoIenden allmahlich verschmaIert, flachin AxiaIrichtung doch im Querschnitt
etwas gew6Ibt, mit stumpf bis scharf
gerundeten, nicht geschnabeIten, dochseIten etwas kopfig geschwollenen ApikaIenden und auch mit geraden oder wenig
konkavem Bauchrand und starker, vor
den Polenden pI6tzlich noch starker
konvexem Riicken, 29-69 f1- lang, 4-5 f1breit; marginale Stacheln entIang
SchaIenrand, in der VaIvarIage aIs ob
Punkt erscheinend, gleichentfernt unddicht liegend, mit transapikalen Streifen
abwechseInd, 8-9 in 10 f1-; Streifen sehrkurz, punktiert, aus 1-3 Punkten bestehend, zur Apikalachse senkrecht und

Der Verfasser ist Herrn Dr. Y. IKEBE,
Vizeprasident von JAPEX, fUr seine
Erlaubnis dieser Ver6ffentIichung und
Herrn F. AKIBA von JAPEX fUr seine
fruchtbare Diskussionen zu groBem
Dank verpflichtet.
Literatur
GLESER, S.1. et al. (1974): Diatomovye vodorosli SSSR, Bd. 1. 1-4, 5-400, 401-404,
Abb. 1-16, Taf. 1-20, 1-93. NAUKA,
Leningrad.
HUSTEDT, F. (1927-64): Die Kieselalgen
Deutschlands, Osterreichs und der Schweiz
mit Beriicksichtigung der iibrigen Lander
Europas sowie der angrenzenden Meeresgebiete: in Rabenhorstes KryptogamenFlora von Deutschland, Osterreichs undder Schweiz, 7. (1): 1-920, Abb. 1-542,(2) : 1-736, Abb. 1-1105, (3): 1-556, Abb.
1-411, Leipzig.
KARSTEN, G. (1928): Bacillariophyta (Diatomeae) : in ENGLER, A.u. PRANTL, K.,
Die natiirlichen Pflanzenfamilien, 2. 105303, Fig. 93-424, Verlag von Wilhelm
Engelmann, Leipzig.

178

Seiichi KOMURAMINATO, M. et al. (1965): The geologic
development of the japanese Islands.
i·xxv, 1-442, Taf. 1-30, Abb. 1-26, Tab.
1-25, Tsukijishokan, Tokio.
NAGAO, S. (1960): Explanatory text of thegeological map of japan, Toyotomi. Ceol.
Surv. Hokkaido, 1-42, Photo. 1-20, Taf.
1-6, 1 Karte.

SHESHUKOVA·PORETZKAJA, V.S. (1967) : Neo·genovy morskie diatomovye vodorosli
Sakhalina i Kamchatki. Izd. LCU, 1-327,
Taf. 1-50, Abb. 1-9, Tab. 1-19.
v AN HEURCK, H. (IS96): A treatise on theDiatomaceae. (iibergesetzt von W.E.
Baxter). i·xx, 1-55S, Taf. 1-35, Abb. 1291. Wisley 'and Son, London.

::It$~;R::ItJ:=OO~~==*f6r~'}f/gElt~~. Kidoa: ;: Q)~.I'l.l:j:>r,,'* • ~l!l!; • ~'UM.l:<, r~Q) 4"?Q) fJU!r~~~~tJ:*- ·n'7.>;: c~ ~l1c"t7.> : 9tJ: IJ t;::.t¥1I!l 1....t.:i'&~· jilij~~t;::,;67.>~'ItQ)::r 7;fjt~jf§· jilij1l!ljitffiit;::,7U1:."t7.> r IT· m$dlt;::ji[~t;::l!7U"t7.>*tlo JlHIl~Q)tJ:
tJ,'"C't'l. Campylosira GRUNOW tJ~J:~Q) ~ t,Q)t'l. Cat>Q) 3,,?Q)~I1~t -:>-n'7.>Q)'"C', m.
Kidoa I'l.;: Q).t;::. t -:> C t;rr~'"C';67.>o 1....tJ'1.... Campylosira l'l.i'&JmJ:Q).'i1;~tJ~Jf':J;liJ!Ut;::5J­;(P"t 7.> Q)t;::%,t 1.... -C, Kidoa t'l.m$dlQ)jjlij1l!Ut;:::J;IBW~t;::re7U"t 7.> Q)'"C', ;: Q).'i1;'"C'jjIij~I'l.120JIj ~n
7.>0 ;: Q)m.I'l.J:~Q)~~~tJ, i?~ -C, Campylosira Q).t ~ t;::I:j:>'L' /3 t;:::totJ,n7.> RJ~~I'l.tJ:<. !if.li?tJ,t;::3fj;fjt/3t;::, :it(:-:>-C Fragilariaceae t;::.:t<"t7.>;:ct;::.tJ:7.>o ;:nl'l.mtE"i'"C'Q)c;: ~*~~~'"C', ;R::ItQ)~*'I-I:j:>'"C'I'l.~ < mt;::, ~ < IUIi)t C tJ:-:> -c!±lm"t 7.>0
tJ::to;:Q)~Q)~fij;IH·~'!J :/:fiilll~~~1J (~)

iU;r=oo* ~p**=J:(;t;::t,tJ:tro'J' ;fJ f,!f -Toyotomi ~&,Tenpoku ;R::It

Erklarungen zur Tafel 24 (Plate 24)
Fig. I-S: Kidoa graviarmata, n. gen., n. sp.
Fig.!. Holotypus. Praparat Nr. jAPEX Fo·ll (34) =14.1x7S.5 (Fm 15636,15635,15634). Koitoi·
Schichten. Oberstmiozan. a: hohe, b: mittiere, c: tiefe Einstellung.
Fig. 2. Paratypus. Praparat Nr. jAPEX Fo-ll (31)=1S.3x90.3 (Fm 15630, 15631). Ebenda. a:hohe, b: tiefe Einstellung.
Fig. 3. Paratypus. Praparat Nr. jAPEX Fo-ll (23)=19.0x90.2 (Fm 15645, 15644). Ebenda. a:tiefe, b: hohe EinsteUung.
Fig. 4. Paratypus. Praparat Nr. jAPEX Fo-ll (25)=13.2xS9.S (Fm 15642, 15640). Ebenda. a:tiefe, b: hohe Einstellung.
Fig. 5. Paratypus. Praparat Nr. jAPEX Fo-ll (14) =S.6xS6.0 (Fm 1562S). Ebenda.
Fig. 6. Paratypus. Praparat Nr. jAPEX Fo-ll (34)=7.2x92.9 (Fm 15633, 15632). Ebenda. a:hohe, b: tiefe Einstellung.
Fig. 7. Paratypus. Praparat Nr. jAPEX Fo-ll (40)=9.1xS3.0 (FmI5626). Ebenda. Schrage
Valvarlage.
Fig ..S. Paratypus. Praparat Nr. jAPEX Fo-ll (27) =5.4xS9.6 (Fm 1563S). Ebenda. Schrage
Valvarlage.

KOMURA:Kidoa, eine neue Diatomeen-Gattung

2aPlate 24

2b
7

1a

1b

1c

4a

4b

5

6a

3a

3b

6b

8

Trans. Proc. Palaeont. Soc. japan, N. S., No. 116, pp. 179-222, pis. 25, 26, December 30, 1979709.

A STUDY OF THE "PENNATAE TRIGONIIDS" FROM JAPAN*
MASA YUKI TASHIRO
Department of Geology, Faculty of Science, Kochi University, Kochi 780

Abstract. The present work is a taxonomic revision of the so-called pennatae
trigoniids from japan, with an attempt to explain the evolutionary parallelism between Hf3terotrigonia and Apiotrigonia. 16 species belonging to the pennatae
trigoniids are known from various localities of the Upper Cretaceous in japan. They
are classified into two genera (Apiotrigonia and Heterotrigonia) and four subgenera(Apiotrigonia s. str., Heterotrigonia s. str., Microtrigonia and Nakanotrigonia nov.).
I propose Apiotrigoniinae nov. as a new subfamily of the Trigoniidae on thesegenera and subgenera together with several other genera and subgenera outsidejapan, such as Columbitrigonia, ?Quoiecchia, Dampietrigonia nov. and Turkestanella
nov. Apiotrigoniinae nov. 'is mainly composed of the Heterotrigonia trunk and the
Apiotrigonia trunk which were probably derived from a common ancestor in theLower Cretaceous. The evolutionary tempo of the Heterotrigonia trunk is more
rapid than that of the Apiotrigonia trunk. Microtrigoniais an off-shoot of Apiotrigonia,
whereas Nakanotrigonia nov. is that of Heterotrigonia. The apparently directionalchanges of characters are recognized in both trunks in parallel with each other.

Introduction

in Southwest japan. Since UEDA andFURUKAWA (1960) reported the biostratigraphy of the Himenoura Group, several
authors, e.g., HATAE (1959, 1960), AMANO(1960a, 1960b, 1962, 1963), UEDA (1962),
YAMAMOTO and HAY AMI (1971), TANAKA
and TERAOKA (1973), TASHIRO and NODA
(1973), TASHIRO (1976), and TASHIRO andOTSUKA (1978), restudied the Himenoura
Group. As a result the stratigraphic
knowledge of the Himenoura Group wasmuch improved, and consequently thestratigraphic ranges of pennatae trigonian
species were also clearly determined. I
once described the evolutionary changeof characters in the pennatae trigoniids
on the basis of the material from theHimenoura Group (TASHIRO, 1972). Subsequently more materials have beenobtained, and my previous work should
be revised and enlarged in the light ofMany species belonging to the socalled "pennatae trigoniids" (pennatae
group, AGASSIZ, 1841; pennata group,
LYCETT, 1872-1879; pinnate forms,
NEWELL and BOYD, 1975, excluding
Iotrigonia and Vaugonia) have been described from various localities of theUpper Cretaceous in japan by elder
authors.
A biostratigraphic study of the Cretaceous trigonians in japan was comprehensively treated by NAKANO (1960).
The stratigraphical positions of pennatae
trigonian species which were listed in
NAKANO (1957, 1960, 1961) are incorrectin certain parts, especially regarding
the species from the Himenoura Group* Received july 13, 1979; read Oct. 20, 1979
in Nagoya.

179

180

Masayuki TASHIRO
tions, with abbreviated indication by
prefix.
GK: Department of Geology, Facultyof Science, Kyushu University(Fukuoka 812)
KE: Faculty of Education, Kumamoto
University (Kumamoto 860)
KSG: Department of Geology, Facultyof Science, Kochi University(Kochi 780)
Acknowledgements

Text-fig. 1. Map showing the localitiesof the pennatae trigoniids in Japan.
°A: Middle Yezo Group; AI. Shimo-katsurazawa, A2. Katsurazawa. B: Mikasa Formation (Turonian part) (Pombetsu). C:
Upper Yezo Group; C1. Saku, C2. Urakawa.
D: Hakobuchi Group (Tomiuchi = Hetanai).
E: Futaba Group; E1. Hirono, E2. Ashizawa. F: Izumi Group; F1. Izumi Mountains, F2. Awaji island, F3. Matsuyama, F4.
Yuasa. G: Sotoizumi Group (Kaiisako
Formation) (Monobe). H: Uwajima G.·oup(Uwajima). I: Onogawa Group (Inukai).
J: Lower Himenoura Subgroup; J1. Uto
Peninsula, J2. Amakusa-Kamishima Island.
K: Upper Himenoura Subgroup; K1. eastern
coast of Amakusa-Shimojima Island, K2.
western coast of Amakusa-Shimojima Island,
K3. Shimo-koshikijima Island.

up-to-date knowledge.
In this paper I offer revised taxonomic
classification of the pennatae trigoniids
from Japan, and attempt to discuss theorigin and evolution of this group.
Repository
The specimens treated in this paper
are stored in the following three institu-

Before going further, I wish to express
my sincere thanks to Emeritus Professor
Tatsuro MATSUMOTO of Kyushu Univ.
for his kind encouragements, criticalreading of the first draft and supplying
me with valuable information and several
specimens from the Upper Cretaceous of
Hokkaido. My sincere gratitude is extended also to Professor Minoru TAMURAof Kumamoto Univ., for his valuablesuggestions and encouragements, to Dr.
Mitsuo NAKANO and Dr. Itaru HAY AMI,
for their kind advice. Thanks are due
to Mr. Katsukichi YAMAMOTO, for the
supplying me several pennatae trigonians
from the Izumi Group, to Mr. Iwane
MIZUNO, from the Uwajima Group, to
Mr. Masao OTSUKA, from the Himenoura
Group, and to Mr. Makoto OKAMURA
from the Upper Yezo Group. My thanks
are extended to Dr. D. H. POULTON of
the Geological Survey of Canada, for
his kind advice and Dr. S. K. SKWARKOof the Bureau of Mineral Resources,
Geology and Geophysics of Australia
for his kind supply of the Australian
specimens.
Revised Classification of thePennatae Trigoniids
Systematic Description

709. Pennatae trigoniids from Japan
Order Trigonioida
Superfamily Trigoniacea
Family Trigoniidae LAMARCK, 1819
Subfamily Apiotrigoniinae nov.
Diagnosis.-Shell usually small, pyriform or trigonally ovate; umbo normallyopisthogyrous, but nearly orthogyrous ina few groups, located more anteriorly
than the mid-point of the valve length;
disk ornamented with two sorts of
costae: the concentric or subhorizontal
ones, occupying the umbonal andanterior parts of the disk and the subradial
ones, developed usually on the posterior
half of the disk, but often also on theanterior part of the disk; area ornamented
with oblique or radial costellae, orsmooth; escutcheon narrow, ornamented
with oblique costellae or smooth; dorsal
and marginal carinae weak or indistinct
except near the umbo; median groove
weak or obscure.
Remarks.-Some genera, e.g., Apiotrigonia and Heterotrigonia, of this new
subfamily resemble Vaugonia CRICKMA Y,
1932, and Iotrigonia VAN HOEPEN, 1929,
in having the reverse L-shaped costae
which are formed by two sorts of costae
on the disk. Vaugonia, however, differsfrom them, in having its distinct
marginal and dorsal carinae, and transversely laminated costellae on the area.
The L-shaped costae of Vaugonia andIotrigonia were probably originated stepby step from the concentriccos tae. Therefore, the costae on the anterior part of thedisk in Vaugonia and Iotrigonia usually
cut across the growth lines from upper
to lower. On the other hand, theL-shaped costae of the genera belonging
to Apiotrigoniinae, appear suddenly at
an early stage of growth, on account of
the appearance of the subradial costae

181

which transversely cross the umbonal
concentric costae. The subhorizontal
costae on the anterior part of the disk
generally cut across the growth lines
from lower to upper. A young shell orumbonal part of some genera of thissubfamily resembles Frenguelliella LEANZA, 1942, and Rutitrigonia VAN HOEPEN,
1929, in their surface ornamentation andtheir outline of a valve as alreadymentioned by TASHIRO (1972). Trigonia
sydariensis ARCHANGELSKI (1916), fromthe Cenomanian of Turkestan, is characterized by feeble subradial costae on theposterior part and concentric costae on
the anterior part. NAKANO (1957) suggested that Trigonia sydariensis isreferable to Rutitrigonia. Rutitrigonia
efr. laeviscula (LYCETT) (SA VELIEV, 1958),
from the Lower Cretaceous of Turkmenia,
is similar to the species of the Apiotrigoniinae in its features of concentriccostae on the disk. Since the Turkmenian species lacks distinct subradial
costae, numerous short costae appear
under the marginal carina. I think, those
two species may represent intermadiate
forms between the Apiotrigoniinae andthe group of Rutitrigonia. Many speciesof Rutitrigonia, e.g., Trigonia pseudoindica ARCHANGELSKI (1916), from the
Cenomanian of Turkestan, T. weaveri
STOY AN ow (1949), from the Aptian ofTexas, Rutitrigonia yeharai KOBAYASHI(1954 ; HAY AMI, 1968) and Rutitrigonia
amagensis KOBAYASHI (1956) from theJurassic of Mindoro, are characterized
by a pyriform outline and plain subhorizontal costae which are obscured on
the posterior part. Though they have no
subradial costae, they resemble thespecies of this subfamily in their featuresof the outline and the ornamentation ofanterior part. VAN HOEPEN (1929) established the subfamily Rutitrigoniinae(Laevitrigoniinae, SA VELIEV, 1958; Fren-

182

Masayuki TASHIRO

guelliellinae NAKANO, 1960) based on his
genus Rutitrigonia VAN HOE PEN), 1929
(type-species: Rutitrigonia peregrina VAN
HOEPEN). NAKANO (1963) amended Rutitrigoniinae towhich he referredFrenguelliella, Geratrigonia KOBAYASHI,
1954, Latitrigonia KOBAYASHI, 1954,
Ibotrigonia KOBAYASHI, 1954, Laevitrigonia LEBKUCHNER, 1933, Linotrigonia
Cox, 1952, Psilotrigonia Cox, 1952,
Nipponitrigonia Cox, 1952, and Rutrigonia.
HAY AMI (1975) listed, however, Frengilelliella, Geratrigonia, Latitrigonia, Nipponitrigonia, Ibotrigonia and Rutitrigonia,
as members of the subfamily Trigoniinae
LAMARCK, 1819. In my opinion, theRutitrigoniinae, the Trigoniinae (KOBAYASH!, 1954; NAKANO, 1961) and theNototrigoniinae SKW ARKO (1963) areclosely related to one another, and they
form a group under the Trigoniidae.
Apiotrigoniinae nov. are also added tothem as one of the members of thisgroup. The Apiotrigoniinaeare mostclosely related to the Rutitrigoniinae,
but discriminated by its subradial costae
on the posterior part of the disk.
List of genera and subgenera.Genus Apiotrigonia Cox, 1952
Subgenus Apiotrigonia Cox, 1952 ;Microtrigonia NAKANO, 1957; Dampietrigonia nov.; Turkestanella nov.
Genus Heterotrigonia Cox, 1952
Subgenus Heterotrigonia Cox, 1952;
Nakanotrigonia nov.
Genus Columbitrigonia POULTON, 1977
?Genus Quoiecchia CRICKMA Y, 1932
Age and distribution.-Upper Jurassic
and Cretaceous; Western Europe, Turkestan, Japan, Sakhalin, Kamchatzka,
Cordillera of North America, southernpart of the interior province of North
America, Central America, western
Australia, Patagonia, Chile and South
Africa.

Genus Apiotrigonia Cox, 1952
Type-species:
Trigonia
sllicataria
LAMARCK, 1819.
Diagnosis.-Shell medium to small fortrigoniids but large to small for the
Apiotrigoniinae; umbo more or ·lessprominent, located anteriorly; disk
ornamented with two sorts of costae:
the concentric or subhorizontal costae,
generally appear on the umbonal partand the anterior part of the disk, andthe subradial ones covering the posterior
part of the disk but sometimes present
on the anterior part of the disk; areasmooth or ornamented by oblique orconcentric costellae; escutcheon depressed, ornamented by oblique or
horizontal costellae, or smooth; escutcheon carina almost invisible except
near the umbo; marginal carina distinctly
angulated near the umbo but graduallychanging into rounded ridge on theposterior part; median groove weak or
indistinct.
Remarks.-The outline of the valve israther constant in each species of thisgenus. The anterior costae of the disk
(anterior series) are variable in number,strength and appearance in each species.
The posterior subradial costae (posterior
series) are, however, rather constant in
number and strength in each species but
for several species, e.g., Apiotrigonia(Apiotrigonia) obsoleta NAKANO.. A. (A.)
crassoradiata NAKANO, A. (? A.) dubia
nov. and A. (Microtrigonia) imlltensis(TASHIRO). The costae of the anterior
series are plain, narrower than theirinterspaces and regularly spaced on theumbonal region. A very narrow marginal
sulcus is recognizable on a portion closest
to the umbo in some species, e.g., Apiotrigonia (Apiotrigonia) minor (Y ABE andNAGAO), A. (A.) utoensis TASHIRO, A. (A.)
undlliosa NAKANO, A. (A.) obsoleta NAKA-

709. Pennatae trigoniids from JapanNO, A. (? A.) dubia nov., A. (Microtrigonia)
amanoi (NAKANO), A. (M.) imutensis(T ASHIRO) and A. (Turkestanella) turkestanensis (ARCHANGELSKI) (subgen. nov.).
TASHIRO (1972) has already illustrated
the umbonal characters of several speciesof this genus.
Age and distribution. - Cretaceous;Western Europe, Turkestan, japan,
Sakhalin, Kamchatzka, Cordillera ofNorth America, southern part of theinterior province of North America,
western Australia, Patagonia, Chile andSouth Africa.
Subgenus Apiotrigonia Cox, 1952
Type-species: Trigonia sulcataria LAMARCK, 1819.
Diagnosis.-Shell large to medium for
Apiotrigoniinae, pyriform, longer thanhigh; umbo weakly prominent, opisthogyrous or nearly orthogyrous in a few
species; disk ornamented by two seriesof costae; anterior ones concentric or
subhorizontal, very often weakly inclined
or undulated, sometimes vanished, locatedon an anterior half or more limited
anterior part of the disk; posterior ones
subradial, sometimes tuberculated, occupying about a posterior half of thedisk; area rather narrow, ornamented
with oblique or subhorizontal costellae,
sometimes sculptured with concentriccostellae; fine concentric plain costellae
regularly spaced on umbonal area insome species; escutcheon narrow, deeply
depressed, ornamented by oblique or
subhorizontal costellae, or smooth onsome foreign species; median groove
shallow.
Remarks.-This subgenus resembles
Heterotrigonia s. str. in the two seriesof costae, but differs clearly from thelatter in its less-developed radial costellaeon the area. Trigonia calderoni (CASTILLO

183

and AGUIERA), from the Upper jurassicof Mexico and Texas (CRAGIN, 1905;
STOY AN ow, 1949), is the oldest species
belonging to Apiotrigoniinae
nov.
SKW ARKO (1970) referred T. calderoni to
Apiotrigonia. NAKANO (1971) crassified
T. calderoni in Heterotrigonia, becauseof its radial costellae on the area. I
think that T. calderoni was a common
ancestor of the species of Apiotrigonias. 1. and Heterotrigonia s. 1. I list here,
Trigonia calderoni as a member of Heterotrigonia s. str., following NAKANO'S
classification. Cox (1952) and NAKANO(1957) referred many species to ApiotriThe species undoubtedly
gonia s. 1.
referable to Apiotrigonia s. str. are as
follows.Trigonia buchi GEINITZ, 1872; Middle
Cretaceous of Sachsen
T. concardiformis (KRAUSS) in KITCHIN(1913); Lower Cretaceous of South
Africa?T. condoni PACKARD, 1921; Aptian ofBritish Columbia
T. cragini STOY ANOW, 1949; Aptian of
Texas
Apiotrigonia crassoradiata NAKANO,
1957; Campanian of japan
A. (? A.) dubia sp. nov.; Maastrichtianof japan
Trigonia heterosculpta STANTON, 1901;
Lower Cretaceous of Patagonia
Apiotrigonia hetonaiana TASHIRO, 1978 ;Maastrichtian of japan
Trigonia kayana ANDERSON, 1938 ;Aptian of California
T. kitchini STOY ANOW, 1949; Aptian ofTexas
T. maudensis WHITEAVES, 1876; Upper
Cretaceous of British Columbia
T. subovalis var. minor Y ABE andNAGAO, 1925; Senonian of Japan andSachalin
Apiotrigonia (Apiotrigonia) mikasaensis
sp. nov.; Cenomanian and Turonian

184

Masayuki TASHIRO

of japan and Sachalin
Trigonia newcombei PACKARD, 1921;'MiddleCretaceous'of British
Columbia
Apiotrigonia obsoleta NAKANO, 1957;
Santonian and Campanian of japan
Trigonia pennata SOWERBY, 1819 ;Cenomanian of England
Apiotrigonia (Apiotrigonia) progonos(PAULCKE) in REYES and PEREZ(1978); Neocomian and Aptian ofChile
T. pumila NILSON in Hi\GG (1954);
Cenomanian of Germany
T. sulcataria LAMARCK, 1819 (Cox,1952); Cenomanian of France
T. turkmenensis ARCHANGELSKI, 1916;
Cenomanian of Turkestan
Apiotrigonia utoensis TASHIRO, 1972;
Lower Campanian of japan
A. undulosa NAKANO, 1957; Coniacianof japan
Trigonia condoni PACKARD, 1921 wasreferred to Megatrigonia (Apiotrigonia)
by JONES (1960), but to Columbitrigonia
by POULTON (1977).
Age and distribution. - Cretaceous;Western Europe, British Columbia, Texas,
California, Patagonia, Chile, Turkestan,South Africa, Sachalin and japan.

Apiotrigonia (Apiotrigonia) minor(YABE and NAGAO)
Plate 25, Figs. 18-20, Text-fig. 21923. Trigonia subovalis lIMBO: YEHARA,
Japan. Jour. Ceol. Ceogr., vol. 2, no. 3,
p. 78, pI. 11, figs. 4-8.
1925. Trigonia subovalis lIMBO var. minor
Y ABE and NAGAO, Sci. Rept. Tohoku
Imp. Univ., ser_ 2,' vol. 7, no. 4, p. 116.
1930. Trigonia subovalis var. minor Y ABE andNAGAO:NAGAO,
Jour. Fac. Sci.,
Hokkaido Imp. Univ., ser. 4, vol. 1, no.
1, p. 18.
1954. Apiotrigonia subovalis minor (Y ABE

and NAGAO) : KOBAYASHI, Japan. Jour.
Ceol. Ceogr., vol. 25, nos. 1-2, p. 77.
1957. Apiotrigonia minor (Y ABE and NAGAO) :NAKANO, Japan. Jour. Ceol. Ceogr.,
vol. 28, nos. 1-3, p. 110, pI. 8, fig. 4,
non. figs. 1-3.
1957. Apiotrigonia obliquecostata NAKANO,Japan. Jour. Ceol. Ceogr., vol. 28, nos_
1-3, p. 113, pI. 8, figs. 9-10.
1962. Apiotrigonia minor (Y ABE and NAGAO) :SAITO, Bull. Fac. Arts and Sci. Ibaraki
Univ., Nat. Sci., no. 13, p. 63, pI. 1,
figs. 8-9.
1962. Apiotrigonia ashizawaensis SAITO, Bull.
Fac. Arts and Sci. Ibaraki Ul~iv., Nat.
Sci., no. 13, p. 63, pI. 1, fig. 6.
1967. Apiotrigonia minor (Y ABE and NAGAO) :MAEDA and KAWABE, Prof. H. SHIBATA Mem. Vol., Tokyo, p. 423, pI. 1, figs.
10-25.
1967. Apiotrigor..ia futabaensis MAEDA andKAWABE, Prof. H. SHIBATA Mem. Vol.,
Tokyo, p. 421, pl. 1, figs. 5-6.
1967. Apiotrigor.ia hironoensis MAEDA andKAWABE, Prof. H. SHIBATA Mem. Vol.,
Tokyo, p. 422, pI. 1, figs. 7-8.
1967. Apiotrigonia orikiensis MAEDA and
KA\VABE, Prof. H. SHIBATA Mem. Vol.,
Tokyo, p. 423, pI. 1, figs. 1-4.
1972. Apiotrigonia minor (Y ABE and NAGAO) :T ASHlRO, Trans. Proc. Palaeont. Soc.
Japan, N.S., no. 86, text-figs, I-b, 3-c,
4 and 6-a, pI. 40, figs. 1-17 (compare,not described).
1975. Apiotrigonia(Apiotrigonia)
minor(Y ABE and NAGAO): HAY AMI, Univ.
Mus., Univ. Tokyo, Bull. no. 10, p. 114.
1975. Apiotrigonia (Apiotrigonia) obliquecostata NAKANO: HAYAMI, Univ. Mus.,
Univ. Tokyo, Bull. no. 10, p. 115.

Material.-KSG 2050-2052, 2059-2060
and KE 1904-1910, collected from theLower Himenoura Subgroup at Wadanohana of Ryugadake-machi, Amakusa
Kamishima Island, Kyushu. KSG 20482049, from the same subgroup at Hinoshima islet of Amakusa KamishimaIsland; KSG 2053-2054, plaster casts
from the Furushiro-yama Formation of

709. Pennatae trigoniids from Japanthe Uwajima Group of Furushiro, Hiromimachi, Uwajima City, Ehime Pref. KSG
2055-2058 are collected from the Lowerpart of the Futaba Group of Hironomachi and Iwaki City, Fukushima Pref.
Description.-Shell medium in size,
moderately inflated; test rather thick;anterior margin semi-circular, passing
gradually into broadly arched ventral
margin; posterior dorsal margin weakly
concave, as long as about a half lengthof the valve; siphonal margin somewhat
broad, well rounded; umbo large but alittle elevated from the dorsal margin,
slightly opisthogyrous, located at about
two-fifths of the length from the frontof the valve; disk ornamented with twoseries of costae; a boundary between theanterior series and the posterior series extending nearly straight from a little posterior of the umbo to the nearly mid-pointof the ventral margin; the costae of theanterior series plain, narrower than theirinterspaces, 10 or more costae on umbonal
region concentric, regularly spaced, next
about 10 costae on the median part ofthe series broadly spaced, horizontal orconcentric in general, but sometimes
oblique, the rest costae of the anterior
series on the anterior ventral part veryvariable in strength, subhorizontal, concentric, oblique, undulated, irregularly
waved, bended in V shape, or disappearing (see, TASHIRO 1972, p. 329, text-fig.
4, pI. 40, figs. 1-13) ; the costae of posterior
series strong, broader than their interspaces, countable between 10 and 13 in
the adult specimens, the first 6 or so of
the series narrow on the upper side but
soon become sturdy on the lower side,
not reaching the ventral margin, of
which the first one begins to appear on
a little posterior of umbo, the other costae
somewhat narrower than those of theanterior ones, reaching subradially theventral margin; escutcheon broad,185

strongly depressed, ornamented with
subhorizontal or slightly oblique numerous plain costellae; area broad, ornamented with two sorts of plain costellae;
one of them occupying nearly the fullsurface of the area except near thesiphonal margin, subhorizontal or oblique,each of which is conjoined with acostella on the escutcheon; the othersort of costellae are concentric or transverse, generally developed near themarginal carina crossing the other sortof costellae; escutcheon carina scarcely
visible only near the umbo; marginal
carina distinct near the umbo but
gradually changing posteriorly into
broadly rounded ridge; median groove
shallow; inner surface smooth; inneranterior margin and posterior part ofthe inner ventral margin broadly
crenulated.
Measurements (in mm).Specimen
KE 1904,
left valve
KE 1905,
left valve
KE 1906,
left valve
KE 1907,
right valve
KE 1910,right valve
KE 1909,
left valve
KSG 2053,
left ex.
mould
KSG 2054,
right ex.
mould
KSG 2055,
right ex.
mould
KSG 2056,
left ex.
mould

LengthHeight Thickness

30.7

22.0

6.4

28.5

19.6

6.5

22.8

17.3

5.5

31.1

20.6

7.0

20.3

15.7

5.8

31.0

25.6

9.0

15.8

10.5

3.2

33.0

24.9

5.6

24.0

18.0

6.6

24.0

16.5

4.5

Remarks.- YABE and NAGAO (1925)
established minor as a variety of Trigonia
subovalis lIMBO, based on many syntypes

186

Masayuki TASHIRO
umbonal concentri c costae( Frenguelliello-Iike stage)subconcentric or
subhorizontal costa e(anterior s,eries)

Text-fig. 2. Illustration and terminology of the costae on the disk of the pennatae
trigonian, based on Apiotrigonia (Apiotrigonia) minor (Y ABE and NAGAO), scale 5 mm.

from several localities of Hokkaido,
North Sachalin, Northeast Japan andSouthwestern Kyushu, but NAKANO (1957)
ranked it up as a distinct species ofApiotrigonia and designated a specimen
as the lectotype which was collectedfrom the lower part of the Futaba Groupof Northeast Japan (Y ABE, 1927, pI. 7,
fig. 4). A form represented by the
specimens from Hokkaido (YEHARA,
1915, pI. 1, figs. 14-17) belongs to Apiotrigonia (Apiotrigonia) mikasaensis nov.,
because its foremost costa of the series
is more numerous than those of thisspecies. The specimens from the lower
part of the Uwajima Group (pI. 25, figs.
9-10), which were collected by Mr. I.
MIZUNO, are small and characterized bymore numerous costae of the posterior
series than those of this species. They
are probably immature shells of Apiotrigonia (Apiotrigonia) undulosa NAKANO,
which is characterized by strong costaeof the posterior series and irregulararrangement of costae of the anterior
series (see, TASHIRO 1972). The variablecostae are also shown in the illustrationsof the specimens from the Futaba Groupby MAEDA and KA WABE (1967).
Occurrence.-Siltstone of the lower
part of the Futaba Group at Oriki of
Hirono-machi, Futaba-gun, and Ashizawa
of Yachi, Iwaki City, Fukushima Prefecture; Inoceramus uwajimensis Zone;
Coniacian; Lower Urakawan. Sandstoneof the upper part of the Furushiroyama
Formation of the Uwajima Group, at
Furushiroyama of Hiromi-machi, Ehime
Prefecrure; Santonian; Urakawan. Blacksiltstone of the Lower Formation of theLower Himenoura Subgroup at Hinoshima, Goshonoura island and Futamado
of Himedo, Amakusa-Kaminoshima area.
Black siltstone of the Middle Formationof the same subgroup at Wadanohana
and Kugujima of Takado, AmakusaKamishima area, Kumamoto Prefecture.
Inoceramus amakusensis and Inoc. japon-

709. Pennatae trigoniids from Japanicus Zones; Santonian; Upper Urakawan.
Apiotrigonia (Apiotrigonia)
mikasaensis sp. nov.
Plate 25, Figs. 1-6, Text-fig. 31915. Trigonia cf. subovalis lIMBO: YEHARA,
Sci. Rept. Tohoku Imp. Univ., ser. 2,
vol. 2, no. 2, p. 42, pI. 1, figs. 14-17.
1957. Apiotrigonia minor (Y ABE and NAGAO) :NAKANO, Japan. Jour. Geol. Geogr., vol.
28, nos. 1-3, p. 110, pI. 8, fig. 1, non.
figs. 2 and 3.

Material.-Holotype KSG 2061, is aright valve from the Ponbetsu (Loc. IK2016), Mikasa area, Hokkaido ; KSG 20682070 (paratypes), from the same locality
as the holotype; GK. H6910-6913 (paratypes), from Ponhorokabetsu, Yubaridome, Hokkaido (Loc. Yb 67r, see MATSUMOTO and HARADA, 1964) (Masato HARADA colI.)
Description.-Shell medium in size,
moderately inflated; test rather thin;anterior margin semi-circular, ventral
margin broably arched on the anterior
part but nearly straight on the posterior;dorsal margin long, weakly concave;siphonal margin somewhat narrow but
well rounded; umbo small, a little prominent, opisthogyrous, located at abouta third or a fourth of the length fromthe front of the valve; disk with twoseries of costae; anterior series plain,narrower than their interspaces, 5 ormore costae on the umbonal region concentric, regularly spaced, next 15 ormore on the median part of theseries subhorizontal but sometimes
weakly waved; on the anterior ventral
part of the adult specimens, the anterior series generally obscured or become
irregularly flexous; the costae of theposterior series number 17 or more,
plain, a little wider than their

187

interspaces, the first 5 or so of the sameseries short, subvertical, not reaching
the ventral margin, of which the firstone begins to appear under the umbo,
the other 12 or so subradial, occupying
the posterior half of the disk; escutcheon
strongly depressed, narrow but elongatedwith about a half length of the valve,ornamented with narrow, plain, subhorizontal costellae; area narrow, ornamented with oblique and narrow costellae,
which are conjoined with the costellaeof the escutcheon near the umbonal oranterior half of the area, but on theposterior half of the area the costellae
are obscured and shown only by fine
growth lines; escutcheon carina obscure;marginal carina distinct near the umbo,
moderatelyangulated, but soon weakened
and changing into rounded ridge on theposterior part of the valve; mediangroove very weak; inner surface weakly
impressed by the subradial ribs of theposterior series.
Measurements (in mm).Specimen
KSG 2068,
right valve
KSG 2061,
right valve
GK.H 6910,
right valve
GK.H 6912,
left valve
GK.H 6913,
left valve

LengthHeight Thickness

19.0

14.3

3.0

17.9

14.0

3.3

34.8

22.1

6.5

33.2

24.5

6.2

31.2

20.5

5.0

Remarks.-This species is one of theoldest species of Apiotrigonia s. str.
from Japan. The specimens which have
hitherto been called "Trigonia subovalis
var. minor YABE and NAGAO" or "Apiotrigonia minor (Y ABE and NAGAO)" from
the Mikasa Formation and the Middle
Yezo Group in Hokkaido can be mostly
referred to this species. The specificname is derived from the Mikasa Formation of central Hokkaido, in which

188

Masayuki TASHIRO

Text-fig. 3. Apiotrigonia (Apiotrigonia)
mikasaensis sp. nov., scale 5 mm.

this species occurs commonly.
Apiotrigonia (Apiotrigonia) minor(Y ABE
and NAGAO) is discriminated from thisspecies by its less numerous and stronger
subradial costae of the posterior series,
less numerous and more irregular costaeof the anterior series, distinct andwidely spaced costellae on the area, andmore posterior location of the foremost(i. e. the first) costa of the posterior
series. Apiotrigonia (Apiotrigonia) undulosa NAKANO is closely similar to thisspecies in its numerous costae of theposterior series and finely waved costaeof the anterior series. The foremost
costa of the posterior series in thisspecies is, however, located more anteriorly than that in A. (A.) undulosa
NAKANO. Other specimens belonging toApiotrigonia s. str. in Japan, e. g., Apiotrigonia(Apiotrigonia)
crassoradiata
NAKANO, A. (A.) hetonaiana TASHIRO,
A. (A.) utoensis TASHIRO, A. (A.) obsoleta
NAKANO and A. (? A.) dubia sp. nov. areclearly discriminated from this species intheir less numerous costae of the anterior
and posterior series, and more posterior
locations of the foremost costa of theposterior series. Heterotrigonia (Heterotrigonia) subovalis (JIMBO), radiate form,(see, p. 210), resembles this species

in its foremost costae which begins toappear under the umbo, but differs in
its distinct radial costellae which are
one of the important characters in
Heterotrigonia s.1., and its less numerous
costae of the anterior and posterior
series.
Occurrence.-Sandstone of the Mikasa
Formation of Ponbetsu, (IK 2016), Mikasa
City, Hokkaido; Inoceramus hobetsuensis
Zone. Sandstone of the Middle Yezo
Group at Yonnosawa of Ponhorokabetsu,
Yubari (Yb 67r, see, MATSUMOTO andHARADA, 1964), Hokkaido. This species
is probably restricted to the Upper
Gyliakian (Turonian).
Apiotrigonia (Apiotrigonia)
undulosa NAKANO
Plate 25, Figs. 7-10, Text-fig. 41957. Apiotrigonia undulosa NAKANO, Japan.
Jour. Ceol. Ceogr., vol. 28, nos. 1-3,
p. 112, pI. 8, fig. 8.
1972. Apiotrigonia undulosa NAKANO: T ASH 1RO, Trans. Proc. Palaeont. Soc. Japan,
N. S., no. 86, pI. 40, figs. 18-19, textfigs. I-a and 2-8 (compare, not described) .
1975. Apiotrigonia (Apiotrigonia) undulosa
NAKANO: HAYAMI, Univ. Mus., Univ.
Tokyo, Bull. no. 10, p. 115.

Material.-KSG 2071-2072 and KE 19251926, imperfect specimens from Sakuradani, Hirono-machi, Fukushima Pref.;KSG 2073-2074, external moulds collectedfrom Hiromi-machi, Uwajima City, Ehime
Pref. by Mr. I. MIZUNO; KSG 2062-2067,
from Kajisako of Otochi, Kami-gun,
Kochi Pref.
Description.-Shell medium in size,
weakly inflated; anterior margin wellarched and nearly semi-circular, ventral
margin long, broadly arched; posterior
dorsal margin elongated and weakly
concave; siphonal margin narrow and709. Pennatae trigoniids from Japan
well rounded; umbo small, slightly
elevated from the dorsal margin, a little
opisthogyrous, located at a fourth oflength from the front of valve; disk
ornamented with two series of costae
except near the umbo; the costae of theanterior series, which occupy about ahalf of the disk, plain, narrower thantheir interspaces, densely crowded andconcentric near the umbo, irregularly
undulated or wavy on the main part,and on the antero-ventral part graduallyobsolete to be represented by growthlines only; the costae of the posterior
series fairly broader than the anteriorones, broader than their interspaces
number about 20, of which the first 10
or so do not reach the ventral margin,
and the first short costa begins to appear
at a point a little posterior to the umbo;
about 10 succeeding costae stretch fromthe postero-ventral carina to the ventral
margin; escutcheon narrow but elongated, ornamented with about 20 or more
subhorizontal and plain costellae; area
somewhat broad, ornamented withnumerous wavy subconcentric costellae
near the umbo, and with numerous
subhorizontal costellae which are connected with the costellae of escutcheonon the anterior half of the area except

Text-fig. 4. Apiotrigonia (Apiotrigonia)
undulosa NAKANO, scale 5 mm.

189

for near the umbo; posterior half of
the area nearly smooth except for fine
growth lines; escutcheon carina indistinct; posterior carina angulated near
the umbo but gradually changing into
roundly elevated ridge; median grooveof the area very weak.
Measurements (in mm).Specimen
KSG 2072,
right ex.
mould
KSG 2073,
left ex.
mould
KSG 2074,
left ex.
mould
KSG 2062,
left valve
KSG 2063,
left valve
KSG 2064,
left valve

LengthHeigth Thickness

23.0

16.0

12.0

11.0

9.0

7.2

19.0

14.2

14.0

11.1)

14.0

11.0

1.8

2.9

Remarks.-Many specimens are collected from the Futaba Group of Northeast Japan and the Uwajima Group of
Shikoku, although some of them areimperfect external moulds. The specimens(pI. 25, figs. 7-10) from Hiromi-machi of
Uwajima and Kajisako of Otochi bothin Shikoku, represent the immature stageof this species. Mature specimens are
generally about 40 mm or more in length.
This species is characterized by thestrongly undulated costae of the anterior
series. Such costae generally appear onsome species of Apiotrigonia s. str., e. g.,
A. (A.) minor (Y ABE and NAGAO) and A.
(A.) crassoradiata NAKANO. In thisspecies, the undulate costae are somewhat crowded and occupy the majorityof the anterior series. This species
closely resembles A. (A.) minor, but it
has undulated costae in the anterior
series and less numerous subradial costaeof the posterior series. This species issimilar to A. (A.) mikasaensis sp. nov. inMasayuki TASHIRO

190

having numerous costae of the posterior
series, but differs in the foremost costaof the posterior series which appears
later in that species. It is probably aderivative from A. (A.) mikasaensis sp.
nov. A. (A.) utoensis TASHIRO resembles
this species in the wavy concentriccostellae near the umbo on the area, but
clearly differs in the plain subradial
costae of the posterior series and its
undulated costae of the anterior series.
Occurrence.-Examined specimens arefrom the lower sandstone of the Futaba
Group at Sakuradani, Hiromi-machi,
Futaba-gun, Fukushima Pre f., from thesandstone of the lower part of the
Furushiroyama Formation of the UwajimaGroup at Hiromi, Kitauwa-gun, Ehime
Pref. and fine-grained sandstone of theKajisako Formation of the Sotoizumi
Group at Kajisako of Otochi, Kami-gun,
Kochi Pref. This species is also reported
from the Inukai Formation of the
Onogawa Group in Oita Pref. by TERAOKA (1970). The holotype designated by
NAKANO (1957) was described from
Taikorin, Oriki, Hirono-machi, Futabagun, Fukushima Pref. This species isprobably restricted to the Turonian(upper part of the Kajisako Formation)
and Coniacian (lower part of the Uwajima Group and the Inukai Formation of
the Onogawa Group). Inoceramus hobetsuensis Zone and I. uwajimensis Zone.

Apiotrigonia (Apiotrigonia)
crassoradiata NAKANO
Plate 25, Figs. 21 and 22

1938. Trigonia subovalis JIMBO, var. minor
YABE and NAGAO: NAGAO and OTA·
TUME, Jour. Fac. Sci., Hokkaido Imp.
Univ., ser. 4, vol. 4, nos. 1-2, p. 42,
pI. 1, fig. 9, non figs. 7 and 8.
1957. Apiotrigonia crassoradiata NAKANO,Japan. Jour. Geol. Geogr., vol. 28, nos.
1-3, p. 113, pl. 8, figs. 9 and 10.
1975. Apiotrigonia (Apiotrigonia) crassora·diata NAKANO: HAYAMI, Univ. Mus.,
Univ. Tokyo, Bull. no. 10, p. 115.
1976. Apiotrigonia crassoradiata NAKANO:TASHIRO, Palaeont. Soc. Japan, SPec.
Pap., no. 19, p. 57, pl. 7, figs. 4-6.
1978. Apiotrigonia crassoradiata NAKANO:TASHIRO, Trans. Proc. Palaeont. Soc.
Japan, N. S., no. 112, pp. 428-431,
Text·figs. 3-5, pI. 54, fig. 5.

Material.-KSG 2077-2085, internal andexternal moulds from Fukkireura of
Shimo-koshikijima Island, Kagoshima
Pref., KSG 2075-2076 and KE 2783, external moulds from Omagari of Tomiuchi(Hetonai), Iburi District, Hokkaido. KE
2127 and KSG 2086, from Himezuka of
Dogo, Matsuyama City, Ehime Pref.
Measurements (in mm).Specimen
KSG 2075,
right ex.
mould
KSG 2076,
right in.
mould
KSG 2077,
left ex.
mould
KSG 2078,
left ex.
mould
KSG 2079,
right ex.
mould
KSG 2086,
right valve

LengthHeight Thickness

42.0

32.2

43.3

29.0

36.5

25.5

9.0

25.0

26.0

7.8

32.5

27.5

7.3

24.0

23.0

7.0

9.9

Remarks.-This species is characterized
by its entirely smooth area, bi- or
trifurcated subradial costae in the posterior series in some adult specimens,
variable ornamentation of the anterior
series and somewhat large size for
Apiotrigonia S. str. The subradial costae,
about 12 in number, are variable in thestrength on the median part of the disk,
as already mentioned in my previous

709. Pennatae trigoniids from Japan
paper (TASHIRO, 1978). The first costaof the posterior series begins to appear
more posteriorly than that of Apiotrigonia(Apiotrigonia) minor (Y ABE and NAGAO).
The posterior carina is distinctly angulated on the earlier half of the valve,
but it rapidly becomes blunt on the later
half.
Occurrence.-Holotype of this species
was described by NAKANO (1957) fromthe basal part of the Izumi Group at
Yuasa of Onsen-gun, Ehime Pref. The
specimens in my hand were collectedfrom several localities as mentioned
below.
Black silitstone of the basal part of
the Izumi Group at Himezuka of Dogo,
Matsuyama City, Ehime Pref. ; Inoceramus(Sphenoceramus) schmidti Zone; Middle
Campanian. Sandstone of the Lower
Member of the Middle Formation(Member U-IIa) of the Upper Himenoura
Subgroup, at about 500 m south of
Fukkireura, and about 200 m north of
Fukkireura, Kashima-mura, Satsuma-gun,Kagoshima Pref. Sandstone of Member
U-IIa of the same subgroup at Yokohama
of Oe, Amakusa-machi, Amakusa-gun,
Kumamoto Pref.; Inoceramus (Sphenoceramus) sachalinensis Zone; Middle Campanian. Fine grained sandstone of the
Hakobuchi Group, at Omagari, Tomiuchi(Hetonai), Iburi District,
Hokkaido ;Inoceramus (Sphenoceramus) orientalis
orientalis Zone; Lower Campanian. A
specimen collected by Mr. Makoto OKAMURA of Kumamoto Univ. from theUpper Yezo Group at Saku, Teshionakagawa-gun, Hokkaido (Inoceramus(Sphenoceramus) schmidti Zone), is identified with this species.
This species is probably restricted to
Lower and Middle Campanian (Lower
Hetonaian).

191

Apiotrigonia (Apiotrigonia)
hetonaiana TASHIRO
1938. Trigonia subovalis var. minor Y ABE andNAGAO: NAGAO and OTATUME, Jour.
Fac. Sci., Hokkaido Imp. Univ., ser. 4,
vol. 4, nos. 1-2, p. 42, pI. 1, figs. 7-8,
non fig. 9.
1978. Apiotrigonia
hetonaiana TASHIRO,Trans. Proc. Palaeont. Soc. Japan,
N.S., no. 112, pp. 425-428, text·fig. 2,
pI. 54, figs. 1-4.

Material.-KE 2776-2782, see TASHIRO,
1978.
Remarks.-Since this species wasreferred to Trigonia subovalis var. minor
YABE and NAGAO, by NAGAO and OTATUME (1938), it has been listed as Apiotrigonia minor (Y ABE and NAGAO) by
NAKANO (1957), SAITO (1961), MAEDA and
KA w ABE (1967) and HAY AMI (1975).
Recently TASHIRO (1978) discriminatedthis species from Trigonia subovalis var.
mino1' Y ABE and NAGAO, and describedin detail as a distinct species of Apiotrigonia, A. hetonaiana TASHIRO.
This species is large for Apiotrigonia
s. str., and characterized by smooth andbroad area, disapperance of the anterior
series, finely crenulated inner anterior
margin and numerous radial striae on
the subinternal surface of the anterior
half of the disk. The subradial costaeof the posterior series are generally
weaker than in several resembling
species, e. g., A. (A.) minor (Y ABE andNAGAO), A. (A.) mikasaensis sp. nov., andA. (A.) crassoradiata NAKANO. This
species is similar to Apiotrigonia (Apiotrigonia) obsoleta NAKANO, in having its
smooth area and obscured costae of theanterior series, but clearly differs in its
larger size of the valve and more
numerous subradial costae of the posterior series than that of A. (A.) obsoleta(12 or more in this species; 4-7 in A.

Masayuki TASHIRO

192(A.) obsoleta). This species is probably
closely related to Apiotrigonia (Apiotrigonia) crassoradiata NAKANO.
Occurrence.-Fukaushi Sandstone of the
Hakobuchi Group at Panketosano-sawaof Tomiuchi (Hetonai), Iburi District,
Hokkaido; Maastrichtian (Upper Hetonaian). Sandstone of the uppermost partof the Chinomigawa Formation of theUpper Yezo Group, at Chinomigawa of
Urakawa, Hidaka District, Hokkaido,
which is somewhat younger than the
Inoceramus (Sphenoceramus) schmidti Zone
or uppermost part of the Inoc. (Sphenoc.)schmidti Zone; Lower Maastrichtian orUppermost Campanian?; Lowest Upper
Hetonaian or uppermost Lower Hetonaian.
The holotype (KE 2776) wascollected at Panketosano-sawa, Tomiuchi.
This species presumably ranges from theuppermost Campanian to Maastrichtian.

Apiotrigonia (Apiotrigonia)
utoensis TASHIRO
1972. Apiotrigonia utoensis TASHIRO, Trans.
Proc. Palaeont. Soc. Japan, N.S., no.
86, p. 333, text-fig. 7, pI. 41, figs. 9-11.
1975. Apiotrigonia (Apiotrigonia) utoensis
TASHIRO: HAY AMI, Univ. Mus., Univ.
Tokyo, Bull. no. 10, p. 115.

Material.- The specimens at my disposal are KE 1881 and 1882 which were
described in my previous study (TASHIRO,
1972, pI. 41, figs. 9 and 10).
Remarks.-This species is discriminatedfrom the other species of Apiotrigonia
s. str. in its numerous transverse striae
on the area and the subradial costae
which are finely tuberculated on theanterior region of the posterior series.
This species resembles Microtrigonia spp.,
e. g., Apiotrigonia (Microtrigonia) amanoi(NAKANO), A. (M.) postonodosa NAKANO,
and A. (M.) imutensis (TASHIRO), in its

tuberculated subradial costae on theposterior series. Apiotrigonia (Microtrigonia) imutensis (TASHIRO) is closely
related to this species in having its
transverse striae on the area. This
species, however, differs from these
species of Microtrigonia in its lessdeveloped subradial costae on the anterior part of the disk.
Occurrence.-Black siltstone of thelower part? of the Upper Formation of
the Lower Himenoura Subgroup (Formation L-III) at Okoshiki beach of Odamachi, Uto City, Kumamoto Pref.; Inoc.
(Sphenoceramus) orientalis nagaoi, Heterotrigonia (Nakanotrigonia) himenourensis(subgen. nov.), and Diplomoceras? sp.
occurred together with this species. The
bed is probably Lower Campanian(Lowest Hetonaian) in age. Black siltstone of the Middle Formation of thesame subgroup, at the western beach of
Kugujima islet, Takado, Ryugadakemachi, Amakusa-gun, Kumamoto Pref.;Inoceramus japonicus Zone; Upper Santonian (Uppermost Urakawan).
Apiotrigonia (Apiotrigonia)
obsoleta NAKANO
Text-fig. 51957. Apiotrigonia obsoleta NAKAKO, Japan.
Jour. Geol. Geogr., vol. 28, nos. 1-3, p.
114, pI. 9, figs. 5-7.
1957. Apiotrigonia minor var. nankoi NAKANO, Japan. Jour. Geol. Geogr., vol. 28,
nos. 1-3, p. 112, pI. 9, figs. 1-4.
1972. Apiotrigonia obsoleta NAKAKO: T ASHIRO, Trans. Proc. Palaeont_ Soc. Japan,
N.S., no. 86, p. 331, pI. 41, figs. 1-8,
non figs. 12 and 13.
1975. Apiotrigonia (Apiotrigonia) obsoleta
NAKANO: HAYAMI, Univ. Mus., Univ.
Tokyo, Bull, no. la, p. 115.

Material.-KE 1891-1903, from Okoshiki
beach of Oda-machi, Uto City, Kumamoto

709. Pennatae trigoniids from Japan
Prefecture.
Description.-Shell small; test rather
thin; umbo small, slightly prominent, alittle opisthogyrous, located at a third
to a fouth from the front of valve;anterior margin well rounded passing
gradually into broadly arched ventral
margin; siphonal margin narrow, wellrounded, somewhat rostra ted to posterior;posterior margin nearly straight, posterodorsal margin gently concave; the costaeof the posterior series occupy about athird of the disk; about 10 of the costaeof the anterior series concentric near
the umbo, regularly spaced and crowded;
those on the succeeding median part ofthe same series broadly spaced, narrower
than their interspaces, nearly subhorizontal, gradually weakened towards venterand posterior, and generally effaced on
the median part of the disk; those on
the ventral part of the same seriesnearly obsolete; the costae of theposterior series very weak, broadly
spaced, 4 to 8 in number, of which 3 orso on the anterior region do not reachthe ventral margin; the first costa of
the series begins to appear at a point
about 5 mm distant from the umbo
towards the posterior; area nearlysmooth except for several concentriccostellae which are conjoined with thecostellae of the escutcheon near theumbo; escutcheon depressed, rather
broad, ornamented with 10 or less than
10 oblique costellae; escutcheon carina
indistinct; postero-ventral carina obtusely
angulated near the umbo, but soonchanging into low and broably roundedridge; median groove of the area very
shallow, but distinct; smooth marginal
sulcus extended along the boundary
between the costate disk and the smootharea; inner surface smooth; innerposterior ventral margin broadly crenulated on some specimens.

193

Text-fig. 5. Apiotrigonia (Apiotrigonia)
obsoleta NAKANO, scale 5 mm.

Aleasurements.-(see, TASHIRO, 1972)
Remarks.-The subradial costae of theposterior series are variable in number,
between 4 and 8. The costae of theanterior series are generally obscure in
the majority of the specimens on thecentral and anterior ventral part of thedisk; but occasionally discernible as
weak costellae in some specimens. The
latter was once called Apiotrigonia
minor var. nankoi by NAKANO (1957), butthere is gradation between it and thesmoothish form in a fossil populationfrom one and the same locality.
This species distinctly differs fromother species of Apiotrigonia s. str. fromJapan, in its less numerous, and low andweak costae on the disk. It may havebeen derived from the main lineage
ranging from A. (A.) 11likasaensis to A.
(A.) hetonaiana (text-fig. 17). It resembles Trigonia maudensis WHITEA YES(PACKARD, 1921) from the Haida
Formation of Queen Chalotte Island,
British Columbia, in having less numerous subradial costae of the posterior
series and somewhat weak costation on
the disk. That species, however, lacked
the costellae on the escutcheon_
The specimens from the Himenoura
Group of Kyushu are larger in size and194

Masayuki TASHIRO

less triangular in outline than thosefrom the Izumi Group of Awaji Island.
These differences could not be regarded
as specific but may be due to the changes
with growth.
Occurrence.-Black siltstone of theUpper Formation (Formation L-III) of
the Lower Himenoura Subgroup, on
Okoshiki beach and Hiraiwa beach of
Oda-machi, Uto City, Kumamoto Pref.;Lowest Hetonaian (Lower Campanian).
Black siltstone of the Middle Formation(Formation L-II) of the same subgroup,at Wadanohana of Takado, Ryugadakemachi, Amakusa-gun, Kumamoto Pref.;Inoceramus japonicus Zone; Upper Urakawan (Santonian). Holotype and paratypes by NAKANO (1957) were describedfrom the Shichi shale (Uppermost
Campanian) and Minato shale (Upper
Campanian) of the Izumi Group of Awaji
Island, Kinki District. This species
ranges probably from Upper Santonian
to Campanian.
Apiotrigonia (? Apiotrigonia)
dubia sp. nov.
Plate 25, Figs. 11-17, Text-fig. 61972. Apiotrigonia aff. obsoleta NAKANO:
T ASHlRO, Trans. Proc. Palaeont. Soc.
Japan, N. S., no. 86, pI. 41, figs. 12
and 13.

Material.-Holotype KSG 2087, is a left
valve, from Azenotani, Sakai City, Izumi
Mountains; KSG 2089 and KE 1935-1936(paratypes), from the same locality ofholotype; KSG 2090-2091 (para types)
from Masuno, Ushibuka City (AmakusaShimojima Island), Kumamoto Pref. The
specimens are external and internalmoulds.
Description.-Shell small, pyriform totrigonal ovate, longer than high; umbo
small, slightly prominent, a little opis-

thogyrous, located at the fourth to fifthfrom the front of valve; anterior margin
semicircular; ventral margin weakly
arched; siphonal margin narrow, rostrated to posterior; posterior margin
nearly straight; the costae of the posterior series occupy about a half or less ofthe disk; the costae of the posterior
series strong but narrow, broadly spaced,finely tuberculated near the posteroventral carina, 7 to 10 in number, of
which 3 or 4 on the anterior region
do not reach the ventral margin; thefirst costa of the series begins to appear
at a point about 2 mm distant from theumbo towards the posterior; about 8 or
so costae of the anterior series concentric near the umbo, closely spaced,
connected with the costellae of escutcheon and area, forming Rutitrigonia or
Frenguelliella-like concentric ornamentation; those on the median part of thesame series broadly spaced, narrower
than their interspaces, nearly horizontal,
about 5 in number, gradually weakened
towards ventral and posterior; those on
the ventral part of same series nearly
obsolete; area ornamented with two
sorts of costellae; subhorizontal costellae
occupy nearly full surface of the area
except for the siphonal part, conjoinedwith the costellae of escutcheon; subvertical costellae also occupy nearly fullsurface of the area except the siphonalpart, conjoined with the subradial costae
on the posterior series of the disk; those
two sorts of costellae cross each other,
forming fine tuberculations; escutcheonrather broad, lanceolated, ornamented
with 8 or more tuberculated subhorizontal
costellae; postero-ventral carina well
remarked; escutcheon carina and mediangroove of the area nearly invisible;
inner posterior ventral margin broadly
crenulated; growth lines very weak or
almost invisible.

709. Pennatae trigoniids from Japan

Text·fig. 6. Apiotrigonia (?Apiotrigonia)
dubia sp. nov., scale 5 mm.

Measurements (in mm).Specimen
KSG 2087,
left ex.
mould
KSG 2088,
right ex.
mould
KSG 2089,
left in.
mould
KSG 2090,
left ex.
mould
KE 1935,
left ex.
mould
KE 1936,
left ex.
mould

LengthHeight Thickness

9.5

6.5

1.6

11.9

8.0

1.9

10.0

7.'J

10.5

7.S

11.0

7.5

15.0

9.5

1.2

Comparison.-This species resembles
Apiotrigonia (Apiotrigonia) obsoleta NAKANO in ornamentation of the disk, butdiffers in its tuberculated sculpture on
the area and the finely tuberculated
subradial costae in the posterior series.
It is similar to Apiotrigonia (Apiotrigonia)
utoensis TASHIRO in its finely tuberculated
subradial costae, but differs clearly inthat the latter has transverse costellaeon the area and numerous concentriccostae in the anterior series. It resembles
Apiotrigonia(Microtrigonia)
amanoi(NAKANO) in the same type of costel-195

lation on the area, but is distingushable
from that species in having less developed subradial costae on the disk. It isalso similar to Apiotrigonia (Microtrigonia) postonodosa NAKANO in the finely
tuberculated subradial costae in theposterior series and the features of theornamentations on the area, but is notcharacterized by so strong and so welldeveloped subradial costae of the posterior series as in that species. The subgeneric assignment of this species to
Apiotrigonia (s. str.) is provisional, since
it has some characters which recall us
Microtrigonia.
Occurrence.-Fine-grained sandstone of
the Azenotani Shale of the Izumi Groupat Azenotani, Sakai City, Izumi Mountains. Fine-grained sandstone of thesame formation at Takinoike, IzumiSano City, Izumi Mountains. Sandstoneof the Middle Member (Member U-IVb,
TASHIRO and OTSUKA, 1978) of the Upper
Himenoura Subgroup, at about 400 m
west of Masuno (roadside exposure),
Oniki-machi, Ushibuka City, Kumamoto
Pref.; Upper Hetonaian (Maastrichtian).
This species is restricted probably to theuppermost Campanian and Maastrichtian,being one of the latest species of thepennatae trigoniids.
Subgenus Microtrigonia NAKANO, 1957
Type-species: Microtrigonia amanoi
NAKANO, 1957; Upper Himenoura Subgroup in Southwestern Japan. Upper
Campanian (Lower Hetonaian).
Diagnosis.-Shell small, roundly subtriangular or pyriform; umbo weakly
opisthogyrous, located anteriorly; disk
ornamented with two sorts of costae:
the concentric plain costae on umbonal
part and the subradial ones tuberculated
generally, appearing on the outer side ofoutskirts of the former; escutcheon

196

Masayuki TASHIRO

narrow with tuberculated oblique ortransverse costellae; area broad with orwithout oblique tuberculated costellae
which conjoined with the costellae ofthe escutcheon; dorsal carina indistinct;
postero ventral carina rather distinct,
angulated near the umbo; median grooveof the area weak or indistinct.
Remarks.-Microtrigonia was eatablished by NAKANO (1957) as a distinct
genus. It was considered as a derivativefrom Apiotrigonia s. str. by NAKANO(1957) and TASHIRO (1972). The intimate
relationships between certain species ofApiotrigonia s. str. and Microtrigonia aresuggested by many features.
Forinstance, a specimen of Apiotrigonia(Microtrigonia) imutensis (TASHIRO) (pI.
26, fig. 10), shows the subradial costaeof the posterior series, like those ofApiotrigonia (Apiotrigonia) minor (Y ABE
and NAGAO) (pI. 26, fig. 18) and A.
(A.) crassoradiata NAKANO (pI. 26, figs.
21, 22) (see Text-figs.). This specimen
may, however, be a malform. Apiotrigonia (Microtrigonia) imutensis (TASHIRO)is closely related to Apiotrigonia (Apiotrigonia) utoensis TASHIRO in the featuresof the area and the tuberculated costaeof the posterior series. The immature
stage of Microtrigonia is nearly identicalwith that of Apiotrigonia s. str. in the
Frenguelliella- or Rutitrigonia-like concentric plain costae of the umbonal
region (see TASHIRO, 1972, text-fig. 1).
A younger shell of Apiotrigonia (Microtrigonia) postonodosa NAKANO does notshow the typical characters of Microtrigonia but has fine tuberculate costaeof the posterior series and less developed
subradial costae on the anterior part ofthe disk. This suggests that A. (M.)
postonodosa may have descended fromsome species of Apiotrigonia s. str.
Microtrigonia is distinguished from
Apiotrigonia s. str. in its tuberulated

A

B

..,
,
,"

,

- ..... __ .. ---Text-fig. 7. Examples showing therelationships between Apiotrigonia s. str.
and Microtrigonia.
Note the "common
zigzag ribbing" appearing on the disks onthree different species of the pennatae
trigoniids. A: Apiotrigonia (Api?trigonia)
minor (Y ABE and NAGAO); B: A. (Microtrigonia) imutensis (TASHIRO); C: A. (A.)
crassoradiata NAKANO, scale 5 mm.

709.

Pennatae trigoniids from Japan

subradial costae which are developed ona certain part of the disk. Several
species of Apiotrigonia s. str., Turkestanella nov. and Dampietrigonia nov., havesubradial sculptures on the anterior partof the disk. For instance, Apiotrigonia(Apiotrigonia) hetonaiana TASHIRO havesubinternal striae on the part, Apiotrigonia(Dampietrigonia)
dampierensis
SKWARKO have fine radial striae, andApiotrigonia (Tu rkestanella) tu rkestanensis(ARCHANGELSKI) is characterized by theMicrotrigonia-like subradial costae. Apiotrigonia (Apiotrigonia) minor (Y ABE andNAGAO) and A. (A.) crassoradiata NAKANO
are very often characterized by theobliquely costated anterior series. Suchsubinternal or external subradial sculptures and oblique costations on theanterior part of the disk, appearing in
Apiotrigonia s. str., Turkestanella nov.
and Dampietrigonia nov., are probably
suggested the relationships between themand Microtrigonia. And the subradial
elements probably indicate one of thecommon characters in the pennatae
trigoniids. I think that these four taxa,
Apiotrigonia s. str., Turkestanella nov.,
Dampietrigonia nov. and Microtrigonia,
can not be distinguished generically. I
regard Microtrigonia as a subgenus of
Apiotrigonia s. 1. Microtrigonia is as yet
unknown from the foreign Cretaceous
sediments. Its known occurrence isrestricted to the Campanian and
Maastrichtian of Japan. It seems likelythat Microtrigonia is one of the end
members of the trigoniid lineages, whichbecame extinct by the end of Cretaceous.
The following species from Japan arereferable to the subgenus Microtrigonia:
A. (M.) amanoi (NAKANO, 1957); Upper
Campanian (type-species of Micro. trigonia)
A. (M.) minima (NAKANO, 1957); Maastrichtian197

A. (M.) imutensis (TASHIRO, 1972);
Campanian
A. (M.) postonodosa NAKANO, 1957;
uppermost Campanian or MaastrichtianA. (M.) sp.; Maastrichtian (this paper)
Distribution.-Campanian and Maastrichtian (Hetonaian) of Japan. Examples
outside of Japan have not yet been
confirmed.
Apiotrigonia (Microtrigonia)
amanoi (NAKANO)
Plate 26, Figs. 1-6, Text-fig. 91957. Trigonia subovalis var. minor Y ABE
and NAGAO: AMANO, Kumamoto Jour.
Sci., ser. B, vol. 2, no. 2, p. 57, pI. 1,
fig. 19.
1957. Microtrigonia amanoi NAKANO, Japan.
Jour. Ceol. Ceogr., vol. 28, nos. 1-3,
p. 117, pI. 9, figs. 21 and 22.
1957. Apiotrigonia
tuberculata
NAKANO,Japan. Jour. Ceol. Ceogr., vol. 28,
nos. 1-3, p. 115, pI. 9, figs. 15 and 16.
1972. Microtrigonia amanoi NAKANO: TASHIRO, Trans. Proc. Palaeont. Soc. Japan,
N. S., no. 86, pI. 40, figs. 26 and 27(without description).

1975. Microtrigonia amanoi NAKANO: HAy AMI, Univ. Mus., Univ. Tokyo, Bull.
no. 10, p. 116.
1975. Microtrigonia tuberculata (NAKANO):HA YAMI, Univ. Mus., Univ. Tokyo,
Bull. no. 10, p. 116.
1976. Microtrigonia amanoi NAKANO: TASHIRO, Palaeont. Soc. Japan Sp. Pcp.
no. 19, p. 57, pI. 7, figs. 10-14.

Material.-KE 1933, 1934, 2130 and 2131,
external moulds, collected from Ukimizu,
Shimo-Koshikijima Island, Kagoshima
Pref. (type locality by Nakano, 1957).
KE 2134, external mould, from Oe of
Amakusa-machi,
Amakusa-shimojima
Island, Kumamoto Pref. KE 2132-2133,
from Himezuka of Dogo, Matsuyama
City, Ehime Pref. KSG 2092-2094, internal

198

Masayuki TASHIRO

....~
(')

.....
~

.....

.....
....

'C:I

Z
<I:

a.

:l<:;

Q

0\
Q

z
<I:

0

....:::,
C

:2
<I:

u
F
G

z

:l<:;

<I:
Z
0
IZ
<I:
(J)

OJ
I:)-

B

Z

:l<:;

<I:

OJ

U

<I:

Q

Z

0

U

Z

0

0:::

::t;;:

::>

I-

~

I

Q

:2
0

z

lLJ

U

A

I

I:)-

709. Pennatae trigoniids from Japanand external moulds, from Azenotani,
Sakai City, Izumi Mountains. KSG 20952098, internal and external moulds, from
Fukkireura of Shimo-Koshikijima Island.
KSG 2099-2100, external moulds, from
Hanzanji, A waji Island, Hyogo Pref.
KSG 2101, external mould, from Hironoof A waji Island. The specimens registeredas KE, were already described by
TASHIRO (1976).
Description.-Shell trigonally ovate,
moderately inflated; umbo slightly
opisthogyrous or nearly orthogyrous,
small, a little elevated from the dorsal
margin, located at about two-fifths fromthe front of the valve; anterior margin
semicircular; ventral margin broadly
arched; siphonal margin obliquely truncated, occupying about a half lenght of
the height of the valve; postero-dorsal
margin nearly straight or slightly convex
but a little concave near the umbo;
antero-siphonal margin bluntly angulated ;disk ornamented with two sorts of
costae; concentric plain ones, narrower

Apiotrigonia (Microtrigonia)
amanoi (NAKANO), scale 5 mm.

Text-fig. 9.

199

than their interspaces, regularly spaced,about 10 in number, occupying umbonal
region which is about one fourth in heightfrom the umbo; several imperfect concentric costae which are crossed by theother sort of costae, forming tuberculations, recognizable under the umbonal
concentric costae, weakened and broadend
towards the venter; the other elementof costae subradial, strong, tuberculated,broader than their interspaces, occupying
the main part of the disk outside theumbonal region, about 9 costae of
posterior extended from the posteromarginal carina to the ventral margin,
the other 6 or more costae appearing on
the anterior marginal part and theanterior part of ventral margin, oblique ornearly vertical on the middle part on theventral, soon bended obliquely on theventral part; escutcheon very narrow
with 10 or more oblique and tuberculated
costellae; area broad, elongated triangular; 7 or so plain and concentriccostellae which conjoined with the costaeof the disk, crowded near the umbo of
the area; 10 or so tuberculated andoblique costellae, which conjoined withthe costellae of the escutcheon, widely
spaced, narrower than their interspaces,
occupying the other part of the area;
escutcheon carina distinct near the umbo,
but obscure on the posterior; theboundary of the area and escutcheon
visible only as a depressed line of theescutcheon; postero-marginal carina
distinctly angulated, weakly concave;median groove of the area indistinct;
inner surface smooth; inner posterior
ventral margin broadly crenulated ; in the

Text-fig. 8. Diagram showing the stratigraphical occurrences and the presumed lineof descent in Apiotrigonia s. str. from Japan. A: Apiotrigonia (Apiotrigonia) mikasaensis
sp. nov., B: A. (A.) minor (Y ABE and NAGAO), C: A. (A.) crassoradiata NAKANO, D: A.
(A.) hetonaiana TASHIRO, E: A. (A.) undulosa NAKANO, F: A. (A.) utoensis TASHIRO, G:
A. (A.) obsoleta NAKANO, H: A. (?A.) dubia sp. nov., scale 5 mm.

Masayuki TASHIRO

200

umbonal region a marginal sulcus-likenarrow band runs under the posteroventral carina; the band ornamented withfine plain vertical costae which conjoinedwith the concentric costae of the diskof I:lmbonal region, forming rever:oe L
shape.
Measurements (in mm).Specimen
KSG 2095,
right ex.
mould
KSG 2096,
left valve
KSG 2097,
left ex.
mould
KSG 2098,
right ex.
mould
KSG 2093,
right ex.
mould
KSG 2092,
left ex.
mould

LengthHeight Thickness

18.0

14.0

3.3

14.5

10.8

1.9

12.3

8.5

1.7

11.9

9.2

1.7

12.5

8.9

2.5

8.5

6.3

1.6

Remarks.- The holotype (GKU. MA.
00001) designated by NAKANO (1957) fromthe Upper Member of the Middle Formation of the Upper Himenoura Subgroup(Member U-lIb), at Ukimizu of Imuta,
Kashima-mura, Shimo-Koshikijima Island,
Kagoshima Pref. (=Imuta Formation at
Ukimizu of Imuta by AMANO, 1957, and
NAKANO, 1957), is small (11.6 mm inlength). It seems to represent a young
stage, being probably a umbonal fragmental specimen. The largest specimen(KE 1934; see TASHIRO, 1976) in mycollection from the type locality ismeasured about 25 mm in length. The
latio of length to height is variable
between 4/5 and 3/5.
This species shows gradual changes inoutline and surface sculptures in accordance with the stratigraphic sequence,in which three representative forms arerecognizable. They are called here the"rostrate", the "typical" and the "tuberculate" forms (see Text-fig. 11). They
are, however, not clearly discriminatedspecifically or subspecifically, since theintermediate specimens are usually foundbetween them.
The rostrate form
generally occurs in the Lower Campanianor the lowest part of the Upper Campanian of the Izumi Group and the Upper
Himenoura Subgroup. The typical form
is found from the Upper Campanian andLowest Maastrichtian? of the Upper
Himenoura Subgroup, the tuberculate form
from the Maastrichtian and the uppermost Campanian of the Izumi Group of
Awaji Island and the Izumi Mountains.
The features of each form are as
follows.Rostrate form :-Shell pyriform androundly subtriangular; area narrow thanin the typical form; umbonal concentriccostae less numerous and occupy anarrower area.
Typical form :-Shell subtriangularly
ovate; umbo improminent; area broader
than in the rostrate form; escutcheonvery narrow.
Tuberculate form: - Shell trigonallyovate, much inflated.
The rostrate form somewhat resembles
Apiotrigonia (Microtrigonia) imutensis(TASHIRO) in its rostrated posterior
siphonal part, but differs in its costellaeon the area and less numerous costae of
the anterior and posterior series. The
tuberculate form is similar to Apiotrigonia (Microtrigonia) postonodosa NAKANO, in its features of costae on the disk,
but differs in its weak and more distinctly tuberculate costae of the posterior
series. The Frenguelliella- or Rutitrigonialike stage is more distinct in the tubercuI ate form and more persistent than inA. (M.) postonodosa. Apiotrigonia tuberculata NAKANO (1957) is identical withthe tuberculate form. What was listed

709. Pennatae trigoniids from Japan
under "Apiotrigonia tuberculata" by
TANAKA and TERAOKA (1973), and MAEDA and KA W ABE (1967) from ShimoKoshikijima Island, Kagoshima Pref., isprobably better to be transferred totypical form.
Occurrence. - Black siltstone of theUpper Member of the Middle Formationof the Upper Himenoura Subgroup(Member U-lIb), at Ukimizu of Kashima,
Satsuma-gun, Kagoshima Pref. Blacksilty sandstone of the Lower Memberof the Middle Formation of the Upper
Himenoura Subgroup, at Fukkireura of
Kashima. Fine-grained sandstone of theLower Member of the Middle Formationof the Upper Himenoura Subgroup(Member U-lIa) at Yokohama of Oe,
Amakusa-machi, Amakusa-gun, Kumamoto Pref. Black siltstone of the basal
part of the Izumi Group at Himezuka of
Dogo, Matsuyama City, Ehime Pref.
Fine-grained sandstone or siltstone of
the Azenotani shale of the Izumi Groupat Azenotani, Sakai City, Izumi Mountains.
Silty sandstone of the Shichi shale ofthe Izumi Group at Hirono, Awaji Island,
Hyogo Pref.; Inoceramus (Sphenoceramus)
schmidti Zone. Campanian and probably
also an uncertain part of the Maastrichtian.
Apiotrigonia (Microtrigonia)
imutensis (TASHIRO)
Plate 26, Figs. 7-12

1972. Microtrigonia
imutensis
TASHIRO,
Trans. Proc. Palaeont. Soc. Japan,
N. S., no. 86, p. 335, text-fig. 9, pI. 40,
figs. 24 and 25.
1975. Microtrigonia
imutensis
TASHIRO:
HAYAMI,
Univ. Mus., Univ. Tokyo
Bull. no. 10. p. 116.
1976. Microtrigonia
imutensis
TASHIRO:TASHIRO, Palaeont. Soc. Japan, Sp.
Pap. no. 19, pI. 7, -figs. 7 and 8 (forcomparison) .

201

Material.-Holotype is KE 1887 (T ASHIRO, 1972) from Ukimizu of Imuta,
Kashima - mura
(Shimo - Koshikijima
Island), Satsuma-gun, Kagoshima Pref.
KSG 2102-2104, from Fukkireura of Imuta,
Kashima-mura.
KSG 2105-2106 from
Yokohama of Oe, Amakusa-machi,
Amakusa-gun, Kumamoto Pref. KSG
2107 from Himezuka of Dogo, Matsuyam a City, Ehime Pref. KSG 2108-2109
from Oshima islet of Ushibuka City,
Amakusa-Shimojima, Kumamoto Pref.
Description.-See TASHIRO, 1972, p. 335.
Measurements (in mm).Specimen
KSG 2102,
right valve
KSG 2103,
right valve
KSG 2104,
left ex.
mould
KSG 2105,
right ex.
mould
KSG 2106,
right ex.
mould
KSG 2107,
left ex.
mould
KSG 2108,
left ex.
mould
KSG 2109,
left ex.
mould

LengthHeight Thickness

25.0

17.0

4.0

17.0

12.2

3.0

16.7

12.5

2.8

24.0

15.0

4.0

22.4

16.5

3.9

18.4

14.7

4.0

11.2

9.3

2.6

13.2

12.5

3.0

Remarks.-This species is clearly distinguished from Apiotrigonia (Microtrigonia) amanoi(NAKANO) in its smooth area,
finer tuberculations of the subradial costae
and more numerous and more crowded
concentric costae on the disk. This
species shows changes in the arrangement of the surface ornamentation inaccordance with the stratigraphic sequence. Three representative varieties
aredis criminated: pseudo-utoensis form
(Text-fig. 3-A), radiate form (Text-fig.
3-B and C) and the typical form (Text-

202

Masayuki TASHIRO

fig. 3-D). Since an intermediate form
usually occur in every case, these threeforms are not treated as subspecies.
The features of the three forms are as
follows.pseudo-utoensis form: - Area
ornamented with fine but distinct concentricor transverse striae, as in Apiotrigonia(Apiotrigonia) utoensis TASHIRO; subradial
costae somewhat less numerous (about
15) and more distinctly tuberculated thanin the other two forms; siphonal marginmoderately rostra ted.
radiate form :-Siphonal margin rostrated; subradial costae well developedon almost the entire surface of the disk,
except for the umbonal concentric
Rutitrigonia or Frenguelliella-like series;
the tubercles of the subradial costae
very fine.
typical form :-Area broader than in
the other two forms; siphonal margin
somewhat truncated; the subradial costae
about 25, being more numerous than inother forms.
The radiate form was sometimes listed
erroneously as Trigonia ogawai (YEHARA,
1923) or Apiotrigonia postonodosa (HATAE,
1959, 1960; MIKI, 1972) from the Lower
Member of the Middle Formation of theUpper Himenoura Subgroup at Yokohama
of Oe. "Trigonia" sp. (n. sp.) of AMANO(1962), from the same member at Oe, is
probably another example of this radiateform.
Occurrence.- The holotype came fromthe black siltstone of the Upper Memberof the Middle Formation of the Upper
Himenoura Subgroup at Ukimizu of
Imuta,
Kashima-mura,Satsuma-gun,Pref. (Shimo-koshikijima
KagoshimaIsland) (T ASHlRO, 1972). The pseudoutoensis form occurs in the black siltstoneof the Lower Formation of the Upper
Himenoura Subgroup (Formation U-I)
at Oshima islet of Ushibuka City, Kuma-

moto Pref. (Amakusa-Shimojima Island),and from the same formation at Fukkireura of Kashima-mura (Shimo-koshikijima Island). Inoceramus (Sphenoceramus)
orientalis orientalis is known from thelocality of Oshima islet. While Inoceramus (Sphenoceramus) elegans pseudosulcatus was collected from the localityof Fukkireura. The radiate form is
known from the black siltstone of thebasal part of the Izumi Group at Himezuka of Dogo, Matsuyama City, Ehime
Pref., occurring together with Inoceramus(Sphenoceramus) schmidti. Another locality of the radiate form is the sandstoneof the Lower Member of the Middle
Formation of the Upper Himenoura Subgroup (Member U-IIa) at Yokohama ofOe, Amakusa-machi, Amakusa-gun, Kumamoto Pref. (Amakusa-Shimojima Island),and the sandstone of the same member
at Fukkireura of Kashima-mura, ShimoKoshikijima Island. Inoceramus (Sphenoceramus) sachalinensis is known from thesame locality as this form in AmakusaShimojima Island. This species is probably restricted to occur in the Campanian (Lower Hetonaian); Inoceramus(Sphenoceramus) orientalis orientalis Zone
and Inoc. (SPhenoc.) schmidti Zone.
Apiotrigonia (Microtrigonia)
postonodosa NAKANO
Plate 26, Figs. 13-17, Text.fig. 10

1957. Apiotrigonia
postonodosa
NAKANO,
japan. jour. Ceol. Ceogr., vol. 28, nos.
1-3, p. 114, pI. 9, figs. 8-14.
1972. Apiotrigonia postonodosa
NAKANO:TASHIRO, Trans. Proe. Palaeont. Soc.
japan, N.S., no. 86, pI. 40, figs. 20-23,
text.figs. 5 and 1-c, 3-d, and 6-B.
1975. Apiotrigonia postonodosa
NAKANO:HAYAMI, Univ. Mus., Univ. Tokyo, Bull.
no. 10, p. 115
1976. Apiotrigonia postonodosa
NAKANO:709. Pennatae trigoniids from Japan
Palaeont. Soc. Japan,
Pap., no. 19, pI. 7, figs. 1-3.

TASHIRO,

Sp.

Material.-KE 1927-1931 and KSG
2113-2114, from Yotsuinosako of Kamihira, Miyanokawachi, Kawaura-machi,
Amakusa-Shimojima Island; KE 21172119, from Ono of Hongo, Miyanokawachi; All the specimens are internaland external moulds.
Diagnosis. - Shell medium for Microtrigonia but small for Apiotrigonia s. 1.,
pyriform to rounded subtrigonal, fairly
inflated; umbo slightly opisthogyrous,
not prominent, located at about onethird to one-fifth from the front of thevalve; anterior margin well rounded;
ventral margin long, broadly arched;siphonal margin narrow, rounded, somewhat rostrated to the posterior; posterodorsal margin straight or weaklyc oncave,
occupying about a half length of thevalve; ratio of length to height about
two-thirds in the adult stage but larger
in younger stages; disk ornamented with
two series of costae: the anterior andthe subradial series, those of the former
concentric, plain, widely spaced, somewhat narrower than their interspaces; 5
or 6 costae on the umbonal region
distinct for about 4 mm in distance fromthe umbo towards the venter; thesucceeding several costae gradually
weakened and broadly spaced, and connected with the subradial series of costae
on the anterior part; and finally thoseon the ventral part of the adult stage,over 10 mm or so in length, become nearly
indistinct; the subradial series of costae
very strong, but narrower than theirinterspaces, finely tuberculated; about 10
costae from the rear of the valve
extended from the postero-ventral carina
towards the ventral margin, nearlystraight, occupying about three-fourths
in length of the disk; 7 or more costae

203on the anterior part short, surroundedby the outskirts of the anterior series,
bi- or trifurcate near the antero-ventral
part; Frenguelliella-like stage of theumbonal region limited only with a few
concentric plain costae; escutcheon
depressed, very narrow, ornamented with
10 or more transverse costellae which
are finely tuberculated, narrower thantheir interspaces, and conjoined with thecostellae of the area; area broad,ornamented with horizontal or obliquecostellae which are finely tuberculated,narrower than their interspaces, number
about 15, of which 3 or so near thesiphonal margin somewhat weaked andirregularly waved; escutcheon carina
indistinct except near the umbo; posteroventral carina angulated on a half
length of itself from the umbo but soonchanging into roundly angulated ridgeon the posterior half; median groove on
the area indistinct; inner surface smooth;posterior inner ventral margin broadly
and strongly crenulated; inner adductor
scars and hinge structures are strongly
impressed for pennatae trigoniids.

Text·fig. 10. Apiotrigonia (Microtrigonia)
postonodosa NAKANO, scale 5 mm.

Masayuki TASHIRO

204
Measurements (in mm).Specimen
KE 1927,
left ex.
mould
KE 1928,
right ex.
mould
KSG 2110,right in.
mould
KSG 2112,
right ex.
mould
KSG 2113,
left ex.
mould
KSG 2114,
right ex.
mould
KSG 2119,left ex.
mould

LengthHeight Thickness

18.4

13.3

3.0

12.5

10.5

2.6

13.3

9.7

2.7

13.4

9.4

2.4

14.8

9.8

2.3

12.3

10.8

3.2

14.9

9.5

3.6

Remarks.- This species was referredto Apiotrigonia s. str. by NAKANO (1957).
As the holotype (GH. NM.00004) and theparatypes (GH. NM.00005-6, GK. H.6021)
are small, the subradial costae which arecharacteristic to Microtrigonia are notshown in these type specimens. JUdging
from the specimens which I collectedfrom the same stratigraphic unit in
Amakusa, the type specimens undoubtedly
represent the younger stage of thisspecies. The largest specimen in mycollection is about 20 mm in length.
Besides the material from the Himenoura Group, this species was also describedby NAKANO (1957) from the Shichi shaleof the Izumi Group at Hanzanji, Miharagun, Awaji Island. As the specimensfrom the Izumi Group in my collection
are very small, it is questionable whether
they are referrable to this species or to
the tuberculate form of Apiotrigonia(Microtrigonia) amanoi (NAKANO). In
fact, this species is closely related to the
tuberculate form of A. (M.) amanoi,
in having the tuberculated subradial
costae and the oblique costellae on the

broad area, but differs in its finer
tubercles on the costae, more rostra ted
siphonal margin and the more restricted
FrengueHiella-like stage on the umbonal
part. The rostrate form of Apiotrigonia(Microtrigonia) imutensis (TASHIRO) somewhat resembles this species in its
rostra ted outline, but clearly discriminated by its smooth area and more
numerous subradial costae of the posterior
series.
Occurrence.-Fine sandstone of theLower Member of the Upper Formationof the Upper Himenoura Subgroup(Member U-I1Ia), at Yotsuinosako of
Kamihira, Ono of Hongo, Keijigahama
and Nodden, all in Miyanokawachi,
Kawaura-machi, Amakusa-gun, Kumamoto Pref. The type locality by NAKANO(1957) (Nodden of Miyanokawachi) is ofnearly the same horizon as the four
localities of this paper. ?Siltstone of
the Shichi shale of the Izumi Group, atHanzanji, Shichi-mura, Mihara-gun, Hyogo
Pref. (Awaji Island); The geological ageof Member U-I1Ia of the Upper Himenoura
Subgroup may be referrable to the uppermost Campanian or Lower Maastrichtian.
The Shichi Shale of the Izumi Group was
assigned to the Uppermost Campanian.

Apiotrigonia (lvIicrotrigonia) sp. indet.
Plate 26, Figs. 19, 20

Material.- Three imperfect specimens(KSG 2120-2122) and two internal moulds(KSG 2123-2124), from Panketosanosawa
of Tomiuchi (Hetonai), Iburi District,
Hokkaido.
Description.-Shell small, roundly triangUlar, longer than high, fairly strongly
inflated; umbo slightly opisthogyrous,
less prominent; anterior margin semicircular; ventral margin broadly arched;siphonal margin small, somewhat angu-

709. Pennatae trigoniids from Japan
lated; posterior dorsal margin nearlystraight but a little concave near theumbo; disk ornamented with two seriesof costae; the subradial costae of theposterior series tuberculated, of which 8
or more extended from the posteroventral carina to the ventral margin,
occupying the posterior half of the disk,
whereas several others appear on theantero-ventral part, short, extending
from a point at some distance from theumbo to the ventral margin; concentriccostae of the anterior series plain; area
broad with oblique costellae; escutcheonvery narrow with numerous transverse
costellae; escutcheon carina indistinct;
postero-ventral carina angulated near
the umbo, but roundly elevated on its
posterior half; inner surface smooth;
inner posterior ventral margin broadly
crenulated, numbering about 6; innerposterior dorsal margin crenulated, about
12; inner siphonal median ridge distinct.
Measurements (in mm).Specimen
KSG 2120, right valve
KSG 2123, left in. mould

Length Height
7.8
5.6
15.0
11.7

Remarks.-Although the details of surface ornamentation of the available
specimens are not clear, this species
resembles Apiotrigonia (Microtrigonia)
postonodosa NAKANO rather than otherspecies of Microtrigonia, in its inflated
valve and less numerous subradial costae.
A. (M.) postonodosa, differs from thisspecies in its strong costae in both
series on the disk. So far it is only
known species of Microtrigonia, from theCretaceous of Hokkaido.
Occurrence.-Fukaushi Sandstone of the
Hakobuchi Group at Panketosanosawa ofTomiuchi (Hetonai), Iburi District,
Hokkaido. The part immediately below
the Zone of Inoceramus (?Sphenoceramus)
Maastrichtian(Upperhetonaianus;

205

Hetonaian).
Apiotrigonia (Microtrigonia)
minima (NAKANO)
1957. Microtrigonia minima NAKANO, Japan.
Jour. Geol. Geogr. vol. 28, nos. 1-3,
p. 119, pI. 9, figs. 21 and 22.
1975. Microtrigonia minima NAKANO: HAYAMI, Univ. Mus., Univ. Tokyo, Bull. no.
10, p. 116.

Remarks.- There is no example of thisspecies in my collection. I indicate it
only for completing the list of species.
Age and distribution.-Campanian and
Maastrichtian (Hetonaian): Shichi Shaleand Kitaama Sandstone of the Izumi
Group in Awaji Island (NAKANO, 1957).

Subgenus Dampietrigollia nov.
Type-species: 'Apiotrigonia' dampierens is SKWARKO, 1969; Aptian; Western
Australia.
Diagonosis.-Shell pyriform; umbo opisthogyrous, located anteriorly; disk ornamented with two series of costae; subradial costae occupying on the wholesurface of the disk but weak on theanterior half, generally tuberculated;concentric costae plain, appear on theanterior half of the disk; area andescutcheon smooth; escutcheon andpostero-ventral carinae weak or indistinct
except near the umbo; median grooveof the area weak.
Remarks.- This new subgenus is proposed on the basis of 'Apiotrigonia'
dampierensis SKW ARKO, 1969, from theMelligo Quartzite of Dampier Peninsula,Western Australia. It is characterized
by the smooth area and escutcheon, andthe subradial costae which cover thewhole surface of the disk including theanterior part. Trigonia calderoni (CASTILLO and AGUILERA) (CRAGIN, 1905;

Masayuki T ASH! RO

206

z
<{

lI
U

0:::

I(f)

w

<{

~

z
<{

z
<{

a.
~
<{

U

A

.....

709. Pennatae trigoniids from JapanSTOY ANOW, 1949; SKW ARKO, 1970), fromthe Jurassic formation of Mexico andTexas, is similar to this type-species
in its smooth escutcheon. While SKW ARKO
(1970) referred T. calderoni to Apiotrigonia, NAKANO (1971) classified T.
calderoni as a member of Heterotrigonia,
because of the presence of weak radialcostellae on the area of T. calderoni. A
few Albian species, Trigonia newcombei
PACKARD (1921) and Trigonia maudensis
WHITE AVES by PACKARD (1921) from the
Haida Formation (Albian) of Queen
Charlotte Island, resemble the typespecies in having the smooth escutcheon
and area. Dampietrigonia is, however,distinguishable from them in that its
subradial costae extend to the anterior
part. Microtrigonia, Nakanotrigonia nov.
and Turkestanella nov. are characterized
by the subradial costae which appear on
the anterior part of the disk. The subradial costae of them are, however,stronger than those of this new subgenus,
and do not develop near the umbo.
Distribution.-Aptian; Western Australia.
Subgenus Turkestanella nov.
Type-species: Trigonia turkestanensis
ARCHANGELSKI, 1916 [=Megatrigonia(Apiotrigonia) turkestanensis : POJARKOVA,
1978J; Cenomanian; Turkestan.
Diagnosis.-Shell trigonal-ovate; umbo
small, less prominent, slightly opisthogyrous, located anteriorly; disk ornamented with Microtrigonia-like costae;

207

area· and escutcheon ornamented withoblique costellae; postero-ventral carina
distinct; escutcheon carina obscure.
Remarks.-This new subgenus is similar
to Microtrigonia in its subradial costae
which develop on the anterior part ofthe disk, but differs in its broader andless numerous subradial costae, and lessnumerous concentric costae on the disk.
Distribution.-Cenomanian; Turkestan.
Genus Heterotrigonia Cox, 1952
Type-species: Trigonia diversicostata
WHITE AVES,
1876; Albian; British
Colombia.
Diagnosis. - Shell small to large,
pyriform and trigonally ovate; umbo
opithogyrous, located anteriorly; disk
ornamented with two series of costae;
subradial ones developed generally on
the posterior part of the disk; extending
sometimes to the anterior part; thecostae of the other series appear on theanterior part of the disk, generally subhorizontal but may be variable in thearrangement and intensity; area ornamented with radial costellae; escutcheon
ornamented with oblique or subhorizontal
costellae, or smooth; postero-ventral
carina and escutcheon carina weak
except near the umbo; median grooveof the area very weak or indistinct.
Remarks.-Heterotrigonia was established as a distinct genus by Cox (1952)
on the basis of Trigonia diversicostata
WHITE AVES, from the Haida Formationof the Queen Charlotte Islands, British

Text·fig. 11. Diagram showing the stratigraphical occurrence and possible lines ofdescent in Apiotrigonia (Microtrigonia) from Japan. A·D: Apiotrigonia (Microtrigonia)
imutensis (TASHIRO), A. pseudo·utoensis form, B. and C. radiate form, D. typical form;
E·H: Apiotrigonia (Microtrigonia) amanoi (NAKANO), E and F. rostrate form, G. typicalform, H. tuberculate form (=Microtrigonia tuberculata NAKANO), I: Apiotrigonia(Microtrigonia) minima (NAKANO), J: Apiotrigonia (Microtrigonia) postoncdosa
NAKANO, scale 5 mm.

208

Masayuki TASHIRO

Columbia. It is distinguishable from
Apiotrigonia in its radial costellae on the
area.
Distribution.-Upper jurassic to Upper
Cretaceous; Northern Pacific region.
Subgenus Heterotrigonia Cox, 1952
Type-species: Trigonia diversicostata
WHITEAVES, 1876.
Diagnosis.-Shell pyriform, umbo prominent, opisthogyrous; disk ornamented
with two series of costae; anterior ones
plain, concentric near the umbo, buthorizontal, oblique, waved or obsolete on
the antero-ventral part, occupying about
the anterior half or less of the disk;
posterior costae plain, occupying theposterior half or so of the disk; area
ornamented with plain radial costellae;
escutcheon narrow,smooth or ornamented
with oblique or subhorizontal costellae;
postero-ventral and escutcheon carinae
indistinct except near the umbo.
Remarks.-Three species, e. g., Trigonia
diversicostata WHITEAVES, from theAlbian of British Columbia, Trigonia
calderoni (CASTILLO and AGUILERA),
from the Upper jurassic of Mexico andTexas, and Trigonia subovalis JIMBO,
from the Cenomanian of japan, arereferable to this subgenus. It resembles
closely Apiotrigonia s. str. in its ornamentations of the disk and the escutcheon,
and its pyriform outline of the valve.
Unless the area is observable, it may bedifficult to discriminate Heterotrigonia s.
str.. from Apiotrigonia s. str.
Distribution.-Upper
jurassicandCretaceous; Northern Pacific region,
Central America (Mexico and Texas).
Heterotrigonia (Heterotrigonia)
subovalis (jIMBO)
Plate 26, Figs. 23-24, Text-fig. 12

1894. Trigonia subovalis JIMBO, Pal. Abh.,N. F. Bd. 2, Ht. 3, pp. 188-189, pl. 8,
figs. 5 and 5a.
1923. Trigonia sawatai YEHARA, Japan. Jour.
Ceol. Ceogr., vol. 3, p. 80, pl. 10, fig. 9.
1954. Heterotrigonia sawatai (YEHARA): KoBAYASHI, Japan. Jour. Ceol. Ceogr.,
vol. 25, nos. 1-2, p. 77.
1957. Apiotrigonia jimboi NAKANO, Japan.
Jour. Ceol. Ceogr., vol. 28, nos. 1-3,
p. 115, pI. 8, figs. 5-7.
1957. Heterotrigonia subovalis (lIMBO) : NAKANO, Japan. Jour. Ceol. Ceogr., vol. 28,
nos. 1-3, p. 118, pI. 8, figs. 13-15.
1961. Heterotrigonia subovalis (lIMBO) : NAKANO, .Trans. Proc. Palaeont. Soc. Japan,
N. S., no. 42, p. 57, pl. 9, figs. 1-14.
?1960. Megatrigonia (Apiotrigonia) subovalis(lIMBO):LIVEROVSKAJA,
Palaeont.
Bull., 2, Leningrad, pp. 251-252, pI. 5,
figs. 1-3.
1975. Apiotrigonia (Heterotrigonia) subovalis(lIMBO): HAYAMI, Univ. Mus., Univ.
Tokyo, Bull. no. 10, p. 115.

Material.-KSG 2125-2128, external andinternal moulds from Keirinbashi of
Shimo - Katsurazawa,
MikasaCity,
Hokkaido; KSG 2129-2130 from thePonbetsu River (Loc. near Ik 2016),
Mikasa City, Hokkaido; GK. H6051 and6055, collected at Ik 2021, on the Ponbetsu River, by T. MATSUMOTO.
Description.-Shell large, pyriform,
moderately inflated, longer than high;test rather thick; umbo slightly prominent, located at about one third or one
fourth of length from the front of thevalve; anterior margin well rounded;
ventral margin moderately arched;siphonal margin weakly rounded orsomewhat truncated obliquely, slightly
rostrate; posterior dorsal margin weakly
concave; disk ornamented with twoseries of costae: anterior ones plain,
generally weak, of which several on theumbonal region are concentric, those on
the anterior ventral part nearly obsolete,709. Pennatae trigoniids from Japan

209

Text-fig. 12. Diagramatic sketches showing two shapes of Heterotrigonia (Heterotrigonia) subovalis (JIMBO). A: radiate form (form of Trigonia sawatai) , B: typicalform, scale 5 mm.

and those on the median part generally
subhorizontal, variable in the arrangement, oblique, wavy and sometimes disappear; the costae of posterior series
subradial, generally weak, broadly
spaced, numbering about 10 or more, of
which 2 or so near the umbo do notreach the ventral margin and the next
2 or so are very often bi- or trifurcatednear the ventral margin; area ornamented
with radial costellae which are veryvariable in number and strength andsometimes effaced; escutcheon depressed,
narrow, ornamented with fine and plain
horizontal or oblique costellae; escutcheoncarina indistinct; posterior carina
distinct near the umbo but laterchanging into roundly elevated andconcave ridge; median groove on thearea very shallow.
Measurements (in mm).Specimen
KSG 2127,
right ex.
mould
GK. H6051
left valve
GK. H6055,
right valve

LengthHeight Thickness

32.0

24.1

8.4

43.2

33.3

10.8

48.9

38.2

12.0

Remarks.- This species was describedin detail by NAKANO (1957, 1961). It isvariable in the features of the surface
ornamentation. Trigonia sawatai YEHARA,
1923, and Apiotrigonia jimboi NAKANO,
1957, are here regarded as synonyms of
Heterotrigonia (Heterotrigonia) subovalis.
However, two forms are represented in
the same fossil population of this species.
Radiate form (form of T. sawatai):Subradial costae of the posterior series
appear distinctly under the umbo;
anterior series irregularly waved on. theanterior ventral part; radial costellae on
the area numerous and distinct.
"Typical form": - Subradial costae
weak, less numerous than in the radiate
form; costae of the anterior series nearly
disappear on the anterior ventral part;
radial costellae on the area very weakand discernible only on the umbonal
region; umbonal angle somewhat broader
than in the radiate form.
This species differs from Heterotrigonia(Heterotrigonia) calderoni (CASTILLO andAGUILERA) from the Upper Jurassic of
Mexico and Texas, and H. (H.) diversicostata (WHITE AYES) from the Albian ofBritish Columbia, in its distinct costellaeon the escutcheon. Two imperfect speci-

Masayuki TASHIRO

210

Z
"'TJ
:::0

lj>

rli-l
0

z
C
:::0

z

«

l>

z

A

o

~
en

l>

:E

<!

~

l>

B

z

z

8
G"I

Z

-<

<!
Z

r

a::

l>

o

::l
I-

:i
o
a:iu
z

Aiotrpigonia (Apiotrigonia) mikasaensis
nov. of the same locality in its lessnumerous costae on the disk.
Occurrence.-Sandstone of the Mikasa
Formation at Keirinbashi of Shimokatsurazawa, Ikushunbetsu, and on the
Pombetsu River (Ik 2021), both in Mikasa,
Central Hokkaido; Middle Cenomanian.
?Sandstone of the upper part of theMikasa Formation of Ponbetsu (Ik 2016) ;Turonian. Sandstone of the upper part(lId) of the same formation at an
abandoned quarry, NWW of the Katsurazawa-dam, Ikushunbetsu; Turonian.

A

l>

z

A

«

in

--l

<!

Text·fig. 13. Diagram showing thestratigraphical occurrences and the pre·sumed line. of descent in Heterotrigonias.l. from Japan. A: Heterotrigonia (Hetero.
trigonia) subovalis (JIMBO) ; B: H. (Nakano.
trigonia) granosa NAKANO; C: H. (N.)
himenourensis TASHIRO, scale 5 mm.

mens (KSG 2129 and 2130) of the present
species are in my collection from a higher
part of the Mikasa Formation (Inoceramus
hobetsensis Zone: Middle Turonian), (Ik.2016). They do not show clearly thecharacters of the area. They differ fromSubgenus Nakanotrigonia nov.
Type-species: Heterotrigonia himenourensis TASHIRO, 1972; Lower Campanian.
Diagnosis. -Shell small, trigonal-ovate,
a little longer than high; umbo small,less prominent, slightly opisthogyrous;
disk ornamented with two sorts of
costae; the plain, concentric ones onumbonal part and subradial, tuberculated
ones extending to the outer part of theoutskirt of the umbonal concentric ones;
area rather broad, ornamented withseveral tuberculate radial costellae;
escutcheon very narrow, with numerous
tuberculate, oblique costellae; escutcheoncarina indistinct; postero-ventral carina
rather angulated; median groove indistinct; Frenguelliella-like stage of umbonal region distinct.
Remarks.-This subgenus differs from
Heterotrigonia s. str. in having the tuberculated costae and costellae on the surface,
and the well developed subradial costaeof the posterior series. It is similar to
Microtrigonia in its well developed andtubrculated posterior series. Microtrigoniais, however, devoid of the radial costellaeon the area.
List of species.Heterotrigonia (Nakanotrigonia) granosa709. Pennatae trigoniids from Japan
NAKANO, 1957; Santonian; Japan.
H. (N.) himenourensis TASHIRO, 1972;
Lower Campanian; Japan.
Distribution. - Santonian and Lower
Campanian; Japan. No species has been
known outside Japan.
Heterotrigonia (Nakanotrigonia)
himenourensis TASHIRO
Plate 26, Fig. 25
1972. Heterotrigonia himenourensis TASHIRO,Trans. Proc. Palaeont. Soc. Japan, N. S.,
no. 86, p. 334, pI. 41, figs. 14-16, text·fig. 8.
1975. Apiotrigonia (Heterotrigonia) himeno·
urensis (TASHIRO): HAYAMI, Univ.
Mus., Univ. Tokyo, Bull. no. 10, p. 116.

Description and lvIeasurements.-(seeTASHIRO, 1972).
Remarks.-This species differs from
Heterotrigonia (Nakanotrigonia) granosa
NAKANO in its distinct postero-ventral
carina, well developed subradial costaeof the posterior series, and bi- or trifurcate subradial costae on the anteroventral part of the disk.
Occurrence.-Black siltstone of theUpper Formation of the Lower Himenoura Subgroup (Formation L-III) at
Okoshiki and Hiraiwa beaches of Oda,
Uto City, Kumamoto Pref. (Uto Peninsula); lower Lower Campanian; Lowest
Hetonaian.
Heterotrigonia (Nakanotrigonia)
granosa NAKANO
1957. Heterotrigonia granosa NAKANO, Japan.
Jour. Ceol. Ceogr., vol. 28, nos. 1-3,
p. 119, pI. 8, fig. 16.
1975. Apiotrigonia (Heterotrigonia) granosa(NAKANO) : HAYAMI, Univ. Mus., Univ.
Tokyo, Bull. no. 10, p. 116.

Remarks.- This species resembles Apiotrigonia (lvIicrotrigonia) amanoi (N AKA-

211NO), in its suboval outline and tuberculated costae and costellae on the disk
and escutcheon, but clearly differs in its
distinct radial costellae on the area.
Occurrence.-Black siltstone of the
Middle Formation of the Lower Himenoura Subgroup (Formation L-II), at
Wadanohana of Takado, Ryugadakemachi, Amakusa-gun, Kumamoto Pref.;Inoceramus japonicus Zone; Santonian(Upper Urakawan).

Genus Columbitrigonia PauL TON, 1977 .
Type-species:
Trigonia
columbiana
PACKARD, 1921.
Remarks.-This genus is characterized
by well developed subradial costae ofthe posterior series. In young stage itshows the surface ornamentations oftypical Apiotrigonia. PauL TON (1977)
referred it to Megatrigoniinae VAN
HOEPEN, together with Apiotrigonia.
Age and distribution. - Albian, southwestern British Columbia.
?Genus Quoiecchia CRICKMA Y, 1932
Type-species: Quoiecchia aliciae CRICKMAY, 1932.
Remarks.- This genus is debatable as
to its taxonomic position.
It wasreferred to the Laevitrigoniinae by
SAVELIEV (1958), but to the Myophorellinae by PauL TON (1977). It is characterized by subvertical or subradial costae
on the posterior part of the disk where
the costae extend from the posteroventral ridge to the ventral margin.
Its costae resemble more closely to thoseof the posterior series of Apiotrigonia
s. str. or Heterotrigonia s. str. than the
costation of lvIyophorella and Laevitrigonia. Its less opisthogyrate umbo andless angulated postero-ventral ridge areMasay'/!-ki TASHIRO

212

also similar to those of the pennatae
trigoniids ..
Age and distribution.-Lower Cretaceous, British Columbia.

Evolutionary changes of thesubfamily Apiotrigoniinae
The earliest species of pennatae
trigoniids is represented by Trigonia
calderoni (CASTILLO and AGUILERA)(CRAGIN, 1905; STOY ANOW, 1949; SKW ARKO, 1970), from the Upper Jurassic of
Mexico and Texas. T. calderoni is characterized by its smooth escutcheon andfinely radiating area as mentioned by
SKWARKO (1970) and NAKANO (1971).
The disk of T. calderoni is ornamented
with subhorizontal plain costae on theanterior part, subradial or subverticalcostae on the posterior, and fine regular
SpeciesHet. (Het.)

concentric costae on· the umbonal part.
Such a costation on the disk is one of
the important characters of pennataetrig()niids.. The anterior subhorizontal
costae. (anterior series) meet with theposterior subra·dial op.~~ (posterior series)
usually on the central part of the disk,
forming the reversed L sculptures. As
illustrated by STOY ANOW (1949, pI. 14,
figs. 1 and 2), the umbonal region of
T. calderoni is characterized by Frenguelliella- or Rutitrigonia-like regularly
spaced and plain concentric costae. Sucha Frenguelliella- or Rutitrigonia-likestage is generally observable on theumbonal region of numerous species inpennatae trigoniids, as has already been
mentioned by TASHIRO (1972). T. calderoni,
is probably a common ancestor of many
species belonging to Apiotrigonia s. I.
and Heterotrigonia s.l., which flourishedextensively in the Cretaceous period.

cenom.Tur·leon·lsanton. I CampanianIMaestricht.

subova/is- --Hel.(Nok.) granosa
Het. (Nak.) himenourensis
Ap: (Ap,) mikasaensis
Ap. (Ap.)minor

Ap. (Ap.) crassoradiota
Ap. (Ap.) hetonaiano
Ap. (Ap.) undu/osa---xAp. (Ap.) utoensisX

Ap. (Ap.) obso/eto--

Ap. (lAp.) dubia
Ap. (Micr.) imufensis--

Ap. (Micr.) amanoi. - - ..

Ap. (Mlcr.) posfonodosa
Ap. (Micr.) minimax

Ap. (Micr.) sp.

x
Gvliakian I Urakawah I

Hetonaian

Text-fig. 14. The stratigraphic ranges of the pennatae trigoniid species from Japan.

709. Pennatae trigoniids from Japan
Heterotrigonia is known from the
Cenomanian and Turonian (Gyliakian) of
Hokkaido in Japan. It is represented by
Trigonia subovalis JIMBO (1894), which is

Text-fig. 15.

213

characterized by numerous radial costellaeon the area. T. subovalis is very changeable in the number and strength of thecostae and costellae. The subradial

Map showing the distributions of the pennatae trigoniids in the world.

Microf'rigonlo/
Aplofrigonlo

Heferofrlgonio

UP. JUR.

LOWER

Text-fig. 16.

CRETACEOUSUPPERCRETACEOUS

Possible lines of descent of the pennatae trigoniids.

214

Masayuki TASHIRO

costae are weakened or bi- or trifurcate
on the ventral part, and the subhorizontal
costae are weakened, irregularly waved
or sometimes disappearing in the matureor late aged specimens. Heterotrigonia
s. str. began to appear, probably in theUpper Jurassic, as shown by the occurrence of Trigonia calderoni in Central
America, and disappeared in the Middle
Turonian (K4b2 by MATSUMOTO, 1977)of Japan, with the downfall of Trigonia
subovalis. The distribution of Heterotrigonia was shifted from Central America
to Japan along the North Pacific Coast,passing through British Columbia, where
Heterotrigonia diversicostata and radiating "Trigonia newcombei" (NAKANO, 1961,1971), are known.
Heterotrigonia s. str. is undoubtedly
succeeded by Nakanotrigonia nov., which
occurs in the Santonian and Lower
Campanian (K5b and K6al) of Japan.
Nakanotrigonia is characterized by tuberculate radial costellae on the area andtuberculate subradial costae which
occupy nearly the whole surface of thedisk except for the narrow umbonalpart, crossing to plain concentric costae.
Nakanotrigonia is probably a branchwhich offshooted from the Heterotrigonia
trunk represented by the successive species
from T. calderoni to T. subovalis by way of
T. diversicostata and "T. newcombei", as
has already been pointed out by NAKANO(1961, 1971). Text-fig. 13 diagramaticallyillustrates the three species of Heterotrigonia s. I. from Japan, showing the
successive change with age. Also textfig. 12 shows two varied forms of
Heterotrigonia (Heterotrigonia) subovalis.
Dampietrigonia nov., based on 'Apoitrigonia' dampierensis SKW ARKO (1969) fromthe Aptian of Western Australia, ischaracterized by the smooth area andescutcheon, and numerous subradial
costae which invade into the anterior

part of the disk. Dampietrigonia wasprobably derived from Trigonia calderoni
or some other pennatae trigoniids in the
Early Cretaceous. The close relationshipbetween T. calderoni and Dampietrigonia
is shown by their smooth escutcheonand somewhat truncated siphonal margin.
Apiotrigonia s. str. is the most flourishedgroup in the pennatae trigoniids (Apiotrigoniinae), characterized by the absenceof radiating costellae on the area. The
earlier representatives of Apiotrigonia
are several species from the Lower
Cretaceous of Central America and SouthAmerica (STOY ANOW 1949, ANDERSON
1938, STANTON 1901). The latest one isrepresented by Apiotrigonia (Apiotrigonia)
hetonaiana, from the Maastrichtian (K6bl)of Japan. Some species of Apiotrigonia
s. str. from the Lower Cretaceous, aregenerally characterized by the regularly
arranged costae of the anterior series
and the escutcheon without costellae.
On the other hand, the species of APiotrigonia s. str. from the Upper Cretaceous
are characterized by the variable arrangement of the anterior series and thecostellate escutcheon. The Campanianand Maastrichtian species, such as A.
(A.) hetonaiana and A. (A.) crassoradiata,
probably represent the last phase of theevolutionary trend in the main trunk of
Apiotrigonia s. str., as shown by their
extraordinarily bi- or trifurcate subradial
costae of the posterior series and theirregularly waved or effaced costae of
the anterior series. Similar features arealso observable in H. (H.) subovalis, thelatest species of Heterotrigonia s. str.
On the other hand, the earlier species ofHeterotrigonia, e. g., H. (H.) calderoni
and H. (H.) diversicostata, are similar to
the earlier ones of Apiotrigonia s. str.
of the Lower Cretaceous, e. g., A. (A.)
cragini, A. (A.) kitchini and A. (A.)
kayana from North America, and A. CA.)

709. Pennatae trigoniids from Japan
UP. JURASSIC

LOW. CRETACEOUS

UPPER

215

CRETACEOUS

Text-fig. 17. Diagram showing the directionally increasing radial ornaments on thedisk of the pennatae trigoniids and the evolutional parallelism between trunks of Heteror_ 0 trigonia and Apiotrigonia.
A: Heterotrigonia (Heterotrigonia) calderoni; B: H. (H.) diversicostata; C: H. (H.) subovalis; D: H. (Nakanotrigonia) himenourensis; E: Quoiecchia
aliciae; F: Apiotrigonia (Apiotrigonia) pennata; G: A. (A.) mikasaensis; H: A. (A.)
crassoradiata; I: A. (A.) hetonaiana; J: A. (Microtrigonia) amanoi; K: A. (Dampietrigonia) dampierensis; L: Columbitrigonia columbiana; M: A. (Turkestanella) turllestanensis;
N: A. (A.) obsoleta.

and A. (A.) condoni from
British Columbia, in their regularly
arranged costae of the both series on the
disk. These similarities in successivechanges with geological age imply theevolutionary parallelism between Apiotrigonia and Heterotrigonia.
In sofar as I know, the origin ofApiotrigonia s. str. was probably in theLower Cretaceous of Central America,
as that of Heterotrigonia s. str. Apiotrigonia s.1. expanded its distribution into
three directions. One was the same asin the case of Heterotrigonia s. str., extending from Central America to Japan
newcombei

along the North Pacific coast. The
second route was from Central America
to Central Asia (Turkestan), passing
Texas, England and France, along thenorthern coast of the Tethys Sea. The
third one was presumably from thenative home to western Australia passing
through South America and South Africa,
along the South western Pacific coast.
This is suggested by the subgenus
Dampietrigonia from Australia by way
of A. (A.) heterosculpta STANTON, 1909)
from Patagonia, A. CA.) progonos (PAULCKE) (REYES and PEREZ, 1978) from
Chile and A. (A.) concardiformis (KRAUSS)

216

Masayuki TASHIRO

from South Africa (KITCHIN 1913).
CoLumbitrigonia POULTON (1977), fromthe Lower Cretaceous (Barremian toAlbian) of British Columbia, is characterized by extraordinarily developed
subradial costae of the posterior series.
It is undoubtedly derived from Apiotrigonia s. str., because the immature shell
has distinctly the Apiotrigonia-type costae
as illustrated by POULTON (1977, pi. 2,
figs. 22, 24, 28, 29, 30, 33, 38, 41, 42 and
43 ; pi. 3, figs. 22 and 23). CoLumbitrigonia
probably offshooted from the Apiotrigonia
trunk in an early Cretaceous time.
Quoiecchia CRICKMAY (1932), from theLower Cretaceous of British Columbia,
is doubtful in the systematic position.
For the reasons which I mentioned in p.
212, I regard it as a member of thepennatae trigoniids (Apiotri:goniinae),presumably a branch from the Heterotrigonia trunk.

Microtrigonia NAKANO, 1957, fromJapan, is undoubtedly derived from Apiotrigonia s. str., with Apiotrigonia (APiotrigonia) utoensis as its presumableancestor. Microtrigonia closely resembles
Nakanotrigonia and TurkestaneLLa in theornamentation of the disk, but differsfrom Nakanotrigonia in its less developed
radial costellae on the area, and fromTurkestaneLLa in its more numerous costaeof the posterior and anterior series.
Microtrigonia is the latest branch fromthe Apiotrigonia trunk, as Nakanotrigonia
is so from the Heterotrigonia trunk.
Microtrigonia appears, however, later
than Nakanotrigonia (Microtrigonia in theLower Campanian as compared with
Nakanotrigonia in the Santonian) (seeText-figs. 16, 18).
TurkestaneLLa, from the Cenomanian ofTurkestan, may also be a derivative fromthe Apiotrigonia trunk.

Text-fig. 18. Presumed phylogenetic relations in the subfamily Apiotrigoniinae nov.
T: Trigoniinae, B: Apiotrigoniinae, R: Rutitrigoniinae and Megatrigoiinae; A: Apiotrigonia
trunk, H: Heterotrigonia trunk.

709.

Pennatae trigoniids from Japan

The Apiotrigonia trunk ranges fromthe lowest Cretaceous to the uppermost
Cretaceous, accompanied with several
branches, e. g., Columbitrigonia in the
Neocomian, Dampietrigonia in the Aptian,Turkestanella in the Cenomanian andMicrotrigonia in the Campanian. The
Heterotrigonia trunk probably ranges
from the Upper Jurassic to the lower
Lower Campanian, accompanied with thebranches of Quoiecchia(?) in the Lower
Cretaceous and Nakanotrigonia in the
Santonian (see Text-fig. 18).
In my opinion, the phylogenetic
evolution ·of the pennatae trigoniids(Apiotrigoniinae) probably took placesystematically in a definite direction
which is manifested by the development
or increase of the subradial costae, theso-called posterior series, and the degeneration of the concentric or subhorizontal
costae, the so-called anterior series (seeText-fig. 17). The directional evolution
proceeded on the trunks of Apiotrigonia
and Heterotrigonia in parallel with eachother, and also in several branches which
offshooted from the both trunks. The
evolutional tempo in each branch or
trunk was not constant.
References
AGASSIZ, L. (1840): Etudes critiques sur les
Mollusques Fossiles, Memoire sur les
Trigonies, 58 p., 11 pis., (Neuchatel).
AMANa, M. (1957): Upper Cretaceous molluscan fossils from Shimo-Koshikijima,
Kyushu. Kumamoto Jour. Sci., ser. B,
sec. 1, Geol., vol. 2, no. 1, p. 63-86, pis.
1-2.
- - (1960a): Geology of Tobase-jima andSenzokuzozo·jima, Amakusa, Kumamoto
Prefecture. Ibid., vol. 4, no. 1, p. 1-12,
pI. L- - (1960b): Geology of Maki·shima and its
neighboring islands, Amakusa, Kumamoto
Prefecture. Jour. Ceol. Soc. Japan, vol.

217

66, no. 783, p. 769-779.
- - (1962): The geologic history of the
Paleo·Shiranui Bay in the Neo·Cretaceous
period (Part 2, Regional geology).
Kumamoto Jour. Sci., ser. B, sec. 1,
Geol., vol. 5, no. 1, p. 1-36.
- - (1963): Geology of Ikara·jima, Izumi·
gun, Kagoshima Prefecture. Ibid., vol. 6,
no. 1, p. 12-17.
ANDERSON, F. N. (1938): Lower Cretaceous
deposits in California and Oregon. Ceol.
Soc. America, Sp. Pap., no. 16, p. 1-339,
pis. 1-48.
ARCHANGELSKI, A. D. (1916): Les mollusquesdu Cretace superieur du Turkestan. Mhn.
Com. Ceoi. Petrograd, N. Ser. Livr. 152,
52 p., 8 pis.
Cox, L. R. (1952): Notes on the Trigoniidae,
with outline of a classification of thefamily. Proc. Mal. Soc. London, vol. 29,
pts. 2 and 3, p. 45-70, pis. 3-4.
CRAGIN, F. R. (1905): Palaeontology of theMalone Jurassic Formation of Texas.
Bull. United States Ceoi. Surv., no. 266,
ser. C, no. 73, p. 1-172.
CRICK:VIAY, C. H. (1932): Contribution towarda monograph of the Trigoniidae. American
Jour. Sci., vol. 24, p. 443-464.
GEINITZ, H. B. (1872-73): Das Elbthalgebirge
in Sachsen. 1, Der untere Quader. 5,
Brachiopoden und Pelecypod en. Palaeontographica, vol. 20, pt. L
HAGG, R. (1954): Die Mollusken und Bra·chiopoden der Schadischen Kreide 4, Sver.
Ceol. Unders., ser. C, no. 535, 72 p., 9pis.
HATAE, N. (1959): On the stratigraphicalboundary between the Upper Cretaceousand Palaeogene strata of Amakusa·
Shimoshima, Kumamoto Prefecture. Sci.
Rep. Kagoshima Univ., no. 8, p. 102-113(in Japanese).
- - (1960): The geology and the geologicalstructure of Amakusa·Shimoshima, Kuma·
moto Prefecture. Ibid., no. 9, p. 61-107(in Japanese).
HAYAMI, I. (1968): Some Jurassic bivalvesfrom Mindoro. Ceoi. Palaeont. South.
east Asia, vol. 5, p. 173-185, pis. 21-22.
- - (1975) : A systematic survey of the218

Masayuki TASHIRO

Mesozoic Bivalvia from Japan. Univ.
Mus., Univ. Tokyo, Bull. no. 10, p. 1-228,
pis. 1-10.
JIMBO, K. (1894): Beitrage zur Kenntnis derFauna der Kreideformation von Hokkaido. Palaeont. Abhandl. N.F., vol. 2, no.
3, p. 149-194, pis. 17-25.
JONES, D. L. (1960):
Lower Cretaceous(Albian) fossils from South-Western
Oregon and their paleogeographic significance. Jour. Palaeont., vol. 34, no. 1,
p. 152-160, pI. 29.
KOBAYASHI, T. (1954): Studies on theJurassic trigonians in Japan. Part 1,
Preliminary notes. Japan. Jour. Geol.
Geogr., vol. 25, nos. 1-2, p. 61-80.
- - (1956): Studies on the Jurassic trigonians in Japan, part 5, Some Jurassic
trigonians from central and west Japan.
Ibid., vol. 27, no. 1, p. 1-8, pI. 1.
- - (1957) : A trigon ian faunule from Mindoro
in the Philippine islands. Jour. Fac. Sci.
Univ. Tokyo, sec. 2, vol. 10, no. 3, p.
351-365, pI. 3.
KITCHIN, F. L. (1913): The invertebrate
fauna and palaeontological relations of
the Uitenhage series. South AfricanMus., Ann., vol. 7, pt. 2, no. 3, p. 21-250,
pis. 2-11.
LEANZA, A. F. (1942): Los Pelecipodos delLias de Piedra Pintada en el Neuquen.
Rev. Mus. de la Plata, N.S. tom. 2, p.
143-206, pis. 1-19.
LEBKUCHNER, R. (1933): Die Trigonien dessiiddeutschen Jura. Palaeontographica,
vol. 77, p. 1-119, pis. 1-16.
LIWEROWSKAJA, E. V. (1960): Stratigraphy
and fauna of the Upper Cretaceous formation in the East Coast of Penshina
Bay. Palaeont. Bull., 2, Leningrad, p.
231-261, pis. 1-6.
LYCETT, J. (1872-79): A Monograph of the
British Fossil Trigoniae. Palaeontographical Soc., 245 p., 41 pis., London.
MAEDA, S. and KAWABE, T. (1967): Apiotrigonia from the Futaba Group in the
Joban District, North Japan. Prof. H.
SHIBATA Memorial Volume, p. 420-425,
pI. 1, table 1.
MATSUMOTO, T. (1977): Zonal correlationof the Upper Cretaceous in Japan. MidCretaceous Events, Hokkaido Symposium,
1976. Palaeont. Soc. Japan, Sp. Pap.,
no. 21, p. 63-74.
- - and HARADA, M. (1964): Cretaceous
stratigraphy of the Yubari dome, Hokkaido. Mem. Fac. Sci., Kyushu Univ., ser.
D, vol. 15, no. 1, p. 79-115, pis. 9-11.
MIKI, T. (1972): Cretaceous-Tertiary unconformity in the western part of Amakusa
Shimoshima. Ibid., vol. 21, no. 2, p. 217237, 2 pis.
NAGAO, T. (1930): On some Cretaceous
fossils from island of Amakusa, Kyushu,
Japan. Jour. Fac. Sci., Hokkaido Imp.
Univ., ser. 4, vol. 1, no. 1, p. 1-25, pis.
1-3.
- - and OTATUME, K. (1938): Molluscan
fossils of the Hakobuchi Sandstone of
Hokkaido. Ibid., vol. 4, nos. 1-2, p. 3156, pis. 1-4.
NAKANO, M. (1957): On the Cretaceous
pennatae trigonians in Japan. Japan.
Jour. Geol. Geogr., vol. 28, nos. 1-3, p.
107-120, pis. 8-9.
- - (1960): Stratigraphic occurences of theCretaceous trigoniids in Japanese Islands
and their faunal significances. Jour. Sci.
Hiroshima Univ., ser. C, vol. 3, p. 215-280.
- - (1961a): On the Trigoniinae. Ibid.,ser. C,vol. 4, p. 71-94.
- - (1961b): Note on Heterotrigonia subovalis (lIMBO). Trans. Proc. Palaeont.
Soc. Japan, N. S., no. 42, p. 55-62, pI. 9.
- - (1963): On the Rutitrigoniinae. Geol.
Rep. Hiroshima Univ., no. 12, p. 513-529,
pI. 56.
- - (1971): A note on Trigonia calderoni(CASTILLO and AGUILERA). Res. Bull.
Hiroshima Inst. Techn., vol. 6, no. 1, p.
11-13.
NEWELL, N. D. and BOYD, D.W. (1975):
Parallel evolution in early trigoniacean
Bivalves. Bull. American Mus. Nat.
Hist., vol. 154, art. 2, p. 55-162.
PACKARD, E. L. (1921): The Trigoniae fromthe Pacific Coast of North America.
Univ. Oregon Publ., vol. 1, no. 9, p. 3-35,
pis. 1-11.
POJARKOVA, Z.N. (1978): Upper Cretaceous

709. Pennatae trigoniids from Japanbivalve mollusca from north Vostochnoj
Area, Central Asia. Akademiia Nauk
Kirgizskoj CCP, p. 1-143, pis. 1-65.
POUL TON, T. P. (1977): Early Cretaceous
trigoniid bivalves of Manning Provincial
Park, Southwestern British Columbia.
Geol. Surv. Canada, Pap. 76-9, 25 p., 3
pis.
REYEs, R. B. and PEREz, E. D' A. (1978):
Las trigonias del Titoniano y Cretacicoinferior de la cuenca Andina de Chile.
Inst. Invest. Geol. Chile, Bol. 32, 105 p.,
5 pis.
SAITO, T. (1962): The Upper Cretaceous
System of Ibaraki and Fukushima Prefecture, Japan (Part 2). Bull. Fac. Arts
and Sci., Ibaraki Univ., Nat. Sci., no. 13,
p. 52-87, 8 pis.
SAVELIEV, A. A. (1958): Lower Cretaceous
trigoniids of Mangyschlak and western
Turkmenia. Trudy Vnigri, no. 125, 516
p., 58 pis.
SKW ARKO, S. K. (1963): Australian Mesozoic
trigoniids. Bur. Min. Res., Geol., Geophys., Australia, Bull. 67, p. 1-55, 6 pis.
- - (1969): Aptian (Lower Cretaceous)'Apiotrigonia' from the Melligo Quartzite
Dampier Peninsula, Western Australia.
Bur. Min. Res., Geol. Geophys., Canberra,p. 227-234, pI. 33.
- - (1970) : An Upper Jurassic Apiotrigonia
from Mexico. Bol. Soc. Geol. Mexicana,vol. 31, no. 2, p. 75-78, pI. 1.
STANTON, T. W. (1901): The marine Cretaceous invertebrates. Princeton Univ. expediteons to Patagonia, 1896-1899, Repts.,
Vol. 4, Paleontology, Pt. 1, 43 p., 10 pis.
STOY ANOW, A. (1949): Lower Cretaceous
stratigraphy in Southeastern Arizona.
Geol. Soc. America, Mem. 38, 136 p., 26
pis.
TANAKA, K. and TERAOKA, Y. (1973):
Stratigraphy and sedimentation of theUpper Cretaceous Himenoura Group in
Koshiki-jima, Southwest Kyushu, Japan.
Bull. Geol. Surv. Japan, vol. 24, p. 157184, pis. 15-24 (in Japanese).
TASHIRO, M. (1972): On the surface ornamentation of the pennatae trigoniids, andon three new species of the trigoniids

219

from the Himenoura Group, Kyushu, Japan.
Trans. Proc. Palaeont. Soc. Japan, N.S.,
no. 86, p. 325-339, pis. 40-41.
- - (1976): Bivalve faunas of the Cretaceous Himenoura Group in Kyushu. Palaeonto Soc. Japan, Sp. Pap., no. 19, 102 p.,
12 pis.
- - (1978): New species of Apiotrigonia
and Senis from the uppermost Cretaceousof Hokkaido.
Trans. Proc. Palaeont.
Soc. Japan, N.S., no. 112, p. 424-433, pI.
54.
- - and NODA, M. (1973): The geologicalage of the "Himenoura Group", Kyushu,
Japan. Jour. Geol. Soc. Japan, vol. 79,
no. 7, p. 465-480, pI. 1 (in Japanese).
- - and OTSUKA, M. (1976): Inoceramus
from Hayaura in Ushibuka City, Kumamoto Prefecture. Ibid., vol. 82, no. 2, p.
139-141 (in Japanese).
- - and - - (1978): Stratigraphical study
on the boundary between the Upper
Cretaceous and Paleogene strata of
Amakusa-Shimojima Island, Kumamoto
Prefecture, Kyushu. Res. Rep. Kochi
Univ., vol. 27., no. 9, p. 113-134, 2 pis.
(in Japanese).
TERAOKA, Y. (1970): Cretaceous formationsin the Onogawa basin and its vicinity,
Kyushu, southwest Japan. Geol. Surv.
Japan, Rep., no. 237, p. 1-84, pis. 1-18.
UEDA, Y. (1962):
The type Himenoura
Group. With palaeontological notes by
MATSUMOTO, T. and UEDA, Y., Mem.
Fac. Sci., Kyushu Univ., vol. 12, no. 2,
p. 129-178, pis. 22-27.
- - and FURUKAWA, N. (1960): On the
Himenoura Group of the Amakusa-Kamishima and adjacent islets, Kumamoto
Prefecture. Sci. Rept., Kyushu Univ.,
Geol., vol. 5, no. 1, p. 35-44 (in Japanese).
v AN HOEPEN, E. C. N. (1929): Die Krytfauna
von Soeloeland, I. Trigoniidae; Pal.
Navorsing Nat. Mus. Bloemfontein, vol.
1, pt. 1, 38 p., 7 pis.
WHITEAVES, J. F. (1876): On some invertebrates from the coalbearing rocks of the
Queen Charlotte Island. Geol. Surv.
Canada., Mesozoic Fossils, Vol. 1, 92 p.,
10 pis.

220

Masayuki TASHIROYABE, H. (1927): Cretaceous stratigraphyof the japanese islands. Sci. Rep. Tohoku
Imp. Univ., ser. 2, vol. 11, no. 1, p. 27100, pis. 3-9.
- - and NAGAO, T. (1925): New or little
known Cretaceous fossils from north
Saghalin. Ibid., ser. 2, vol. 7, no. 4, p.
111-124, pis. 28-29.
YAMAMOTO, S. and HAY AMI, I. (1971): Cretaceous system of Shishijima, Kagoshima

Prefecture. Sci. Rept_, Kyushu Univ.,
Geol., vol. 11, no. 1, p. 35-44 (injapanese) .
YEHARA, S. (1915): The Cretaceous trigoniae
from Miyako and Hokkaido. Sci. Rept.
Tohoku Imp. Univ., ser. 2, vol. 2, no. 2,
p. 35-44, pis. 1-2.
(1923):
Cretaceous trigoniae fromsouthwest japan. Japan. Jour. Ceol.
Ceogr., vol. 2, no. 3, p. 59-84, pis. 8-13.

Explanation of Plate 25
Apiotrigonia (Apiotrigonia) mikasaensis sp. nov.
Fig. 1: GK. H6910; right valve, xl; loco Yonnosawa, Ponporokabetsu, Yubari, Hokkaido.
Fig. 2: GK. H6912; left valve, xl; loco ditto.
Fig. 3: GK. H6913; left valve, xl; loco ditto.
Fig. 4: GK. H6911; left and right valves, xl; loco ditto.
Fig. 5: KSG 2061; right valve, x 1.2; loco Ponbetsu, Mikasa City, Hokkaido.
Fig. 6: KSG 2070; a cluster of specimens, xl; loco ditto.
Apiotrigonia (Apiotrigonia) undulosa NAKANO
Fig. 7: KSG 2064; gum cast of left external mould, x 2; loco Kajisako of Monobe, Kochi
Pref., Shikoku.
Fig. 8: KSG 2065; gum cast of left external mould, x 2; loco ditto.
Fig. 9: KSG 2073; gum cast of left external mould, x 3; loco Hiromi, Uwajima City, Ehime
Pref., Shikoku.
Fig. 10: KSG 2074; gum cast of left external mould, x 2; loco ditto.
Apiotrigonia (?Apiotrigonia) duMa sp. nov.
Fig. 11: KSG 2087; gum cast of left external mould, x5; loco Azenotani, Sakai City, Izumi
Mountains.
Fig. 12: KSG 2088; gum cast of right external mould, x 2.5; loco ditto.
Fig. 13: KE 1935; gum cast of left external mould, x 2; loco ditto.
Fig. 14: KE 1936; gum cast of left external mould, x 2; loco ditto.
Figs. 15, 16: KSG 2090; gum cast of left external mould, x 2; loco Masuno, Oniki-machi,
Ushibuka City, Kumamoto Pref., Kyushu.
Fig. 17: KSG 2091; gum cast of imperfect left external mould, x 5; loco ditto.
Apiotrigonia (Apiotrigonia) minor (Y ABE and NAGAO)
Fig. 18: KSG 2051; left valve, x 2; loco Wadanohana of Takado, Amakusa-Kamishima island,
Kyushu.
Fig. 19: KSG 2054; gum cast of right external mould, xI; loco Furushiroyama, Uwajima
City, Ehime Pref., Shikoku.
Fig. 20: KE 1906; left valve, x 2; loco Wadanohana of Takado, Amakusa·Kamishima island.
Apiotrigonia (Apiotrigonia) crassoradiata NAKANO
Fig. 21: KSG 2075; gum cast of right external mould, xI; loco Omagari of Tomiuchi (Hetonai), Iburi District, Hokkaido.
Fig. 22: KSG 2085; gum cast of imperfect right external mould, xI; loco Fukkireura of
Kashima, Shimo.koshikijima island, Kagoshima Pref., Kyushu.

TASHIRO:

Pennatae trigoniids from Japan

Plate 25

5

6

2

3

4
8

7

10
18

20
17
11
15

......

12

13
16

22

709. Pennatae trigoniids from Japan

221

Amakusa "Je1if.,
Amakusa-Kamishima "Je1if.J:,ill;,
Amakusa-Shiimojima "Je1if.""f,ill;,
AshiAwaji ~~,Azenotani ~/ i:l',Chinomigawa ~L;e:JII,
Dogo }gf3€:,
zawa JEtR,
Fukaushi i?/i!lJ::,
Fukkireura i!J.:-!iUillL
Furushiroyama ~:lBtLlJ,
Futaba ~jf,
Futamado=FI39p,Goshonoura 1!llJmiflj,
Hakobuchi ~lJl!~,
Hanzanji ~LlJ~,
Hetonai Jlt~P:!,
Hidaka B i'i1ii,
Himedo liCip,
Himenoura liCiTili,
Himezuka liCi~,
Hinoshima 1lmz,ill;,Hiraiwa fE,
Hiromi !A.m,
Hirono !A!Ilf,
Hongo *~,
Iburi !lli.l1N,
Ikushunbetsu~*5JIJ,
Imuta M.$[!,
Inukai :;JdO],
Iwaki 1'7 ,-\,-,
Izumi ;f!l7'R,
Kajisako ~{;£~,Kamihira J:f,
Kashima J1g,ill;,
Katsurazawa tttR,
Kawaura VlJrilL
Keirinbashi?-1 V :/1\t,Keiji ~~,
Kitaana ~tjr.JtJIl,
Kita-uwa ~t~;f!l,Kugushima l1"],ill;,
Masuno :tfM!Ilf,
Mihara ?]Jj{.
Mikasa =:~,
Minato ~,Miyanokawachi '8!1lffoJlJ:] ,Oda ~83,
Oe *iI,Okoshiki 1!llJ~*,
Omagari *Ilt!,
Oniki "'J~'-,
Nodden ~[!,
Ono *!Ilf,
On ogawa *!IlfJII,
Onsen ifn\.jR,
Otochi *tm,
Oriki :W*,
Oshima *,ill;,
Panketosanosawa /{:/?- I- -It / tR,
Ponbetsu ;f-:/"" '/ ,Ponhorokabetsu ;f-:/ *' P 71"" '/ ,Ryugadake ~?- ffi,
Sakai JR,
Saku {;£;Z,
Sakuradani t2(i:l',Satsuma ifiJ!llf,
Shichi1.;%1,
Shimokatsura ""ftt,
Shimo-Koshiki Tt/[,
Taikorin!; 1 ::z V :/,Takado i'i1iip,
Takinoike iI'i!/ iU!,
Teshionakagawa "JeJj[J:j:IJiI,Tomiuchi ffip:!,
Ukimizu 1'J!.7lC,
Urakawa TiliJil,
Ushibuka lj::i?/i!,
Uto ~±,
Uwajima ~*1l,ill;,
Wadanohana '1'!-1839,t,Yachi i:l':it!!,Yezo "'" ,/,Yokohama ~~,Yotsuinosako ~;Jf/ j§,
Yonnosawa
11:9/ tR,
Yuasa ~~,
Yubari :9~.

B*.i£: "pennatae trigoniids" O)liJf~: *liJf~lt, *omO)J:'iffltn.lli*il'0%10;/1.G/H~!.
=: ~ ~ "pennatae trigoniids" t:.~-t G M1m~(fJ *jVE 7tM~i¥J liJf~ -c: l> G * om -c: it"Pennatae Trigoniids" it, -I! / -< =- 7 :/--< A I- V 1::. -/7 :/t:.l±l:m. L, 16fj (2 ~fj) il~lii~ ~;/1. Go .:.;/1.0It Heterotigonia c Apiotrigonia t:::.~-tGtO)ct:.:;J(5]Ij-C:~Go
Heterotrigonia t:.~-t G t 0) It Heterotrigonia s. str. 0) 1 :ml c ~ill!J.m Nakanotrigonia0) 2 fjO)llt 3 fjil~l> I), Heterotrigonia s. str. It-\! / -< =- 7 :/-7"- "- p =- 7 :/t:::.il,'! 0;/1.,
Nakanotrigonia It -It:/ I- =- 7 :/-71 :/ /{ =- 7 :/t:.i±',m-t G Apiotrigonia t:.lt Apiotrigonia s. str. c!!E~ Microtrigonia il~l> G Apiotrigonia s. str. It 7"- "- p =- 7 :/--< A lV 1::. -/7 :/ i: "(,t:. 8 fj (2 ~fj) il~l> I), Microtrigonia It 71 :/ /{ =- 7 :/ J;J.~t:::. I±l:m. L, 7c0) 5 fjil'~~ 0;/1. G :;t - A I- '7 V7 O)Dampietrigonia (~!!EJm) -,?J:j:I:9<!: 7 ~ 7 0) Turkestanella (~!!EJm) It, :to7c 0 <""f'iffl, J:j:I'ifflSill!*c.t:. Apiotrigonia il' 07t;oz Lt.: t 0) -c: l> I) ,71 -r!;to) Columbitrigonia It:to7c 0 < Apiotrigonia s. str. c ~JiO)j'f;tJl~ t "? -C\" G c,\~,tb;/1. G i: t.: 71 -r !;t 0) Quoiecchia It Heterotrigonia t:.~Ji L t.:~lID'!iit!lli~f.fi?7c 0)
jVEi¥J~;i!IH1:il''f~ ~;/1.G tJJ:O)Jm· !!E~~ t c t:'~!!E~;~ Apiotrigoniinae ~ID!:5E Lt.:o~.!lU4t:'lt Apiotrigonia trunk c Heterotrigonia trunk 0)=*7Uil~~~ 0;/1., lltr~'It:to7c 0 <""f'ifflS!!E*c.t:.:to\, '-Cf3€:~il' 07t;oz Lt.: c ,~,:b;h., i: t.:jj!ij~rl3't:'lt fIT Lt.:5EItiJi¥JtsJr~
mHfNtil'~~0;/1.Go *~ill!'fiHt, :to7c0 <~ "- '7*c.I3€:JtIlt:::. Frenguelliella il'l>G\"ltmWO)=:~A~JI§WJ(c L-cJ:j:l:9<!:7;1. V71ftj[[~JI§,~t:. L-C7tI&L-C\,'''?t.:c,~,:b;/1.Go i:t.:.*ill!f4
It, Rutitrigoniinae c t '&i~tJ:~f*il~l> G c ,~,:b;h.G
83 ~ IE z
0

0

0

0

**

0

0

0

222

Masayuki T ASH I RO

Explanation of Plate 26
Apiotrigonia (Microtrigonia) amanoi (NAKANO)
Fig. 1: KSG 2092; gum cast of left external mould, x 2.5; 'tuberculate form' ; loco Azenotani,
Sakai City, Izumi Mountains.
Fig. 2: same specimen, x 5.
Fig. 3: KSG 2098; gum cast of right external mould, x 2; 'rostrate? form' ; loco Fukkireura of
Kashima, Shimo-koshikijima island, Kagoshima Pref., Kyushu.
Fig 4: KE 2130; gum cast of right external mould, x 2; 'typical form'; loco Ukimizu ofKashima, Shimo.koshikijima island, Kagoshima Pref., Kyushu.
Fig. 5: KE 1934; gum cast of left external mould, x 2; 'typical form'; loco ditto. Kashima,
Shimo.koshikijima island.
Fig. 6: KSG 2097; gum cast of left external mould, x 2; 'typicai form'; loco Fukkireura of
Kashima, Shimo·koshikijima island.
Apiotrigonia (Microtrigonia) imutensis (TASHIRO)
Fig. 7: KSG 2108; gum cast of left external mould, x 2; 'pseudo-utoensis form'; loco Oshima
of Ushibuka City, Amakusa-Shimojima island, Kumamoto Pref., Kyushu.
Fig. 8: KSG 2104; gum cast of left external mould, x 2; 'radiate form'; loco Fukkireura of
Kashima, Shimo.koshikijima island.
Fig. 9: KSG 2105; right valve, xl; 'radiate form'; loco ditto.
Fig. 10: KSG 2107; plaster cast of left external mould, x 2; 'radiate form' ; loco Himezuka of
Dogo, Matsuyama City, Ehime Pref., Shikoku.
Fig. 11: KSG 2105; gum cast of right external mould, x 1.5; 'radiate form'; loco Yokohama
of Oe, Amakusa·machi, Amakusa·Shimojima, Kumamoto Pref., Kyushu.
Fig. 12: KSG 2106; gum cast of right external mould, x 2; 'radiate form' ; loco ditto.
Apiotrigonia (Microtrigonia) postonodosa NAKANO
Fig. 13: KSG 2117; gum cast of left external mould, x 1.5; loco Ono of Hongo, Miyanokawachi,
Amakusa·Shimojima island, Kumamoto Pref., Kyushu.
Fig. 14: KSG 2118; gum cast of right external mould, x 2; loco ditto.
Fig. 15: KE 1927; gum cast of left external mould, x 2; loco ditto.
Fig. 16: KSG 2116; gum cast of imperfect left external mould, x 2; loco Yotsuinosako of
Kamihira, Miyanokawachi.
Fig. 17: KSG 2115; gum cast of conjoined valves, x 1.5; showing the dorsal view; loco Ono
of Hongo, Miyanokawachi.
Apiotrigonia (Apiotrigonia) utoensis TASHIRO
Fig. 18: KE 1882; right valve, xl; loco Okoshiki of Oda, Uto City (Uto peninsula), Kumamoto Pref., Kyushu.
Apiotrigonia (Microtrigonia) sp. indet.
Fig. 19: KSG 2120; right valve, x 2; loco Panketosanosawa of Tomiuchi (Hetonai), Iburi
District, Hokkaido
Fig. 20: KSG 2123; left internal mould, x 1.5.; loco ditto.
Apiotrigonia (Dampietrigonia) dampierensis (SKWARKO)
Fig. 21: CPC 7723; plaster cast of right external mould (see SK\YARKO, 1969).
Fig. 22: CPC 7729; ditto.
Heterotrigonia (Heterotrigonia) subovalis (lIMBO)
Fig. 23: GK. H6056; left valve, xl; loco Shimokatsura, Mikasa (lK 2021), Hokkaido; collectedby T. MATSUMOTO; 'typical form of subovalis'.
Fig. 24: KSG 2125; plaster cast of imperfect left valve, xl; loco Keirinbashi, Shimokatsura,
Mikasa, Hokkaido; 'radiate form' (form of Trigonia sawatai).
Heterotrigonia (Nakanotrigonia) himenourensis TASHIRO
Fig. 25: KSG 2131; left valve, x 2; loco Hiraiwa of Oda, Uto City, Kumamoto Pref., Kyushu.

TASHIRO:

Plate 26

Pennatae trigoniids from Japan

3
4
S

6

2

8

9

.:

13

.... ....

14

lS

16
17

19

20

23

2S

:

Trans. Proc. Palaeont. Soc. Japan, N. S., No. 116, pp. 223-234, pis. 27, 28, December 30, 1979

710. SOME NEW BIVALVE SPECIES FROM THE LOWER
GYEONGSANG GROUP, KOREA*SEONG YOUNG YANG
Department of Earth Science, Kyungpook National University, Daegu 635, ,~or~~.

Abstract. Two new bivalvian species from the Yeonhwadong Formation, the lciw¢rmost formation of the Gyeongsang Group are described here. ,Trigo7Jioides(Koreanaia) bongkyuni sp. nov. is ornamented with large angled V-shape subradialribs of Koreanaia type and possesses fine crenulated hinge teeth of Wakinoa type.
On account of the stratigraphic relation as well as the morphologic characters, T. (K;)
bongkyuni is reasonably interpreted as a link-species between T. (K.) cheongi andsome species of T. (Wakinoa) in the evolutionary lineage. The other new one"
Pseudohyria matsumotoi, may be considered to be an ancestor of ,other specie,S ofPseudohyria reported from the continental side of Asia in respe~t of the stratigraphic occurrences.

Introduction

Many species referred to the family
Trigonioididae have been reported fromthe Lower Cretaceous formations' in the
Asian Continent including the KoreoJapanese region since the genus" Trigonioides was first established by
KOBAYASHI and SUZUKI (1936) from the
Nagdong Subgroup, Korea. They havebeen known as indices in the non-marine
Cretaceous formations of Asia. But, forfurther precise correlation, and the appropriate allocation of their taxonomic
position, the construction of their
phylogeny is indiE!pensable. The formations yielding these species, unfortunately, are separat,ely distributed here
and there, and thus the phylogenetic
relations amqng them have not yet been
definitely constructed as mentioned previously (YANG, 1978a).
OTA (1963) regarded Trigonipides(s.s.)* Received July 26, 1979; readJan~'ary 22,
1979, at the Annual Meeting of'the 'Palaeontological Society of Japan' at. FukilOka.

as'a derivative from Wakinoa observing
the degree of the development of mediancardinal teeth in the two :subgenera_
HAYAMI (in HAYAJ.\.;II and ICHIKAWA, 1965)
considered that Wakinoa was a common,ancestor of, Trigonioides,' (s; s.) andNippononaia or that Trigonioides'(s.s.) was
derived from 'Nippononaia throughWakinoa with 'regard to' the hinge
structure ,and other' morphologic characters. After thal, I revised the evolutionary lineage such as Koreanaia- Wakinoa
Nippononaia-Trigonioides (s. s.)-Kumamotoa from the stratigraphic relations
and their;. morphologic characters' andpresented the Koreanaia cheongi as anultimate ,ancestor of the trigonioidid
species (1976, .1978b). The evolutionary
trend was' also supported from the comparison of the T. (s. s.) kodairai and T.
(s. s.) pauc.isulcatus (YANG, 1978a).
Recently, I discovered a new fossil
locality) 'from the lowermost formationof the Gyeongsang Group, Korea. Amongthe collection, a new trigonioidid species
described 'below presents a fairly inter-

223

Seong Young YANG

224

2km

tI;;;g;J;;b;g;;a:;;;;;;;=~=;;;;j1

Text-figure 1. Geologic map around the fossil locality (generally after 5.0. Ci-iOl
and Y.!. K WON, 1970). 1. Pre-Gyeongsang gneiss, 2. Pre-Gyeongsang granite, 3. Yeonhwadong Formation, 4. Hasandong Formation, 5. Dongmyeong Formation, 6. Acidic dyke,
7. Alluvium.
Fossil locality. In the index map at the lower right corner, D: Daegu,
J: jinju, B: Busan, G.S.B.: Gyeongsang Main Basin.

x

esting feature certainly considered to
be intermediate between K. cheongi and
W. wakinoensis. This is supported also
by the stratigraphic evidence.
The other new species is referred to
Pseudohyria, which has not been reported
from Koreo-Japanese region. From thestratigraphic occurrence, the new speciesof Pseudohyria is possibly an ancestor ofvarious species of Pseudohyria reported
from the Asian Continent.
This is to report systematically thetwo new species with some brief noteson the stratigraphy of the Gyeongsang
Group.
Acknowledgements-I would like to express my sincere gratitude to Emeritus
Professor Tatsuro MATSUMOTO of the
Kyushu University for his kind encourage-

ment and also critical reading of thispaper, and to Miss Gumja LEE of theKyungpook National University for her
assistance on field and laboratory works.
This study was financially supportedby the Korea Science & Engineering
Foundation (KOSEF).
Stratigraphic Notes

There have been different proposals
about the stratigraphic subdivision of
the Gyeongsang Group by several authors,
but I do not give any comments on themin this paper. In this paper, the current
scheme of subdivision is used as shownin Table 1.
The Gyeongsang Group is nonconformably underlain by a complex gener-

710. New bivalves from Gyeongsang Group
ally composed of gneisses and granites,
but in one small area of the northern
margin of the Gyeongsang Basin, thegroup is in contact with the possibly
upper Jurassic Myogog Formation withangular unconformity, from which
Koreanaia cheongi was described (YANG,
1976). Assuming that the Yeonhwadong
Formation next above the regional unconformity is almost of the same age
throughout the basin, K. cheongi must
be chronologically earlier than thepresent species.
Table 1.

225

The relation of the two subgroups,
the Nagdong and the Sinla, is apparently
observed as conformable at least near
the type-section. The ruditic rock of
the Paldal Formation shows a gradualchange from the arenites of the Chilgog
Formation lying below generally in thenorthern area of the basin. However,in the southern area, an abrupt lithologicchange at the boundary is observed,
which leads us to regard the relation as
disconformable. The two subgroups are
fairly well distinguishable from eachCurrent scheme of subdivision of Gyeongsang Group.

-1----------I
Bulgugsa intrusives-------------~-

1------,- intrusiveI

I Jusasan andesites

I

I Geoncheonri Fm.

I

----I

-------Chaeyagsan basalts

a..

g

Sinla
Subgroupc::l:)T. (s.s.) paucisulcatus or Jindong Fm.

Banyaweol Fm.
1 - - - - - - - - - - - - - - - - - - -- - - -Haman Fm.

l:)

Z

<:
(f)

Hagbong basalts

l:)

Z

o
(iI _________

~_

>-

-

I

l:)

Paldal Fm.*
conformity (or dis conformity)
Chilgog Fm.

-------------- - -- -----1

Dongmyeong Fm. *Nagdong
Subgroup--------------- ------------

Hasandong Fm.-T. (s.s.) kodairai-----------

Yeonhwadong Fm.*-Nippononaia ryosekiana, T. (K.) bongkyuni,
Ps. matsumotoi---- -~------ -- unconformity

I

Pre·Gyeongsang complex (granites, gneisses) orM~ogog Fm.-T. (K.) cheongi-'-------------------.,----,----------------~---~In spite of CHANG'S withdrawal (1975) of his own proposal (1966) of *Yeonhwadong and*Dongmyeong formations for Nagdong and Jinju formations, respectively, I prefer to use theYeonhwadong and Dongmyeong formations, as the name Nagdong has - been familiar to geo·
logists broadly meaning the lower part of the Gyeongsang Group such as Nagdong flora andNagdong fauna since YABE (1905), and above all, the Nagdong is also used to the subgroup,and the name Jinju is derived from the remote distance from the -type·section.- The *Paldal
formation has been occasionally used for the Sinla conglomerate since SUZUKI (1943), andseems more desirable than the latter on the same reason as above. The Paldal is derived fromthe Paldal·gyo (Paldal bridge) at the type-locality near Daegu.

226

Seong Young YAAG

other by different lithology, that is, theNagdong is composed of rudites, arenites
and lutites, while the Sinla contains
predominantly lutites and subordinately
arenites besides the basal conglomerateof the Paldal Formation. Therefore, it
seems to be more reasonable to divide
the group into the two subgroups thanany other schemes of subdivision. And
there is no problem in stratigraphic
comparison between Geoncheonri Formation (with T. (s. s.) paucisulcatus) andHasandong Formation· (with T. (s. s.)
kodairai).
The subgroups are divided into formations generally on the grounds
whether the reddish beds are intercalated
or not. However, on account of discontinuity of the reddish beds, they can
not be considered as appropriate key
beds (YANG, 1972). Therefore, it is quitedifficult to draw chronology in detailfrom the lithologic units, formations,especially in correlation of the two areasof a great distance aparts. For instance,
no one can say, in the present state ofknowledge, whether the lower Lower
Yeonhwadong Formation near Goryeong
be in fact lower than the middle Lower
Yeonhwadong Formation near Waegwan.
And so the locality of Nippononaia
ryosekiana near Waegwan is hardly
comparable with that of the present fossil
locality. However, the Lower Yeonhwadong Formation and the Middle Hasandong
Formation can be compared with eachother with some chronologie sense. The
present locality falls under the Lower
Yeonhwadong Formation.
While theoccurrences of T. (s. s.) kodairai are confined to the Middle Hasandong Formationeven though the fossils occur very sporadically. Thus, the present. locality canbe said to be stratigraphically lower
than thdse of T. (s. s.) kodairai.
The geology around the present fossil

~

LL

<.!)

Z

~Sh
~~Ms
--

oo

......
······SS
EIJ

LL

l!;!\Gn.............

~ ~Ad
:c
z Im'blcg
@
> mGr
o

100m

Text-figure 2. Columnar section oflower part of the Yeonhwadong Formation,
showing the stratigraphic horizon of thefossil locality. Sh: shale, Ms: mudstoneor siltstone, Ss: sandstone, Ad: acidic
dyke, Cg: conglomerate, Gr: granite, Gn:gneiss.

locality was mapped by CHOI and KWON
(1975), and Text-figure 1 is adapted fromtheir geological map with some modification made by me. The area is locatedon the western margin of the central
part of the Gyeongsang Basin andconsists of the pre-Gyeongsang complex,
the lower part of the Gyeongsang Groupand the acidic dyke as illustrated in
Text-figure 1.

710.

New bivalves from Gyeongsang Group

Systematic Description

Superfamily Unionacea

227

be crenulated in some species. Other
characters same as the original diagnosis(Y ANG, 1976, p. 320).

Family Trigonioididae Cox, 1952
Subfamily Trigonioidinae Cox, 1952
Genus Trigonioides KOBAYASHI &SUZUKI, 1936

Subgenus Koreanaia YANG, 1976
Type-species-Koreanaia cheongi YANG,
1976.

Remarks-Koreanaia was originallyproposed as an independent genus on
account of its large angle of the Vsculptures on the median part andlamellar hinge teeth. Such a combination of characters had been unknown
in the trigonioidid genera, i. e., Trigonioides, H offetrigonia, Nippononaia andWakinoa.
However, a new species
described below is certainly referred to
Koreanaia on account of its similar surface ornamentation and outline, but thehinge teeth are not lamellar but finely
crenulated like Wakinoa. It can be
regarded as a member of Koreanaia withdentition of Wakinoa or a member of
Wakinoa with sculpture of Koreanaia.
Therefore, it is considered as an intermediate species between Koreanaia andWakinoa, that is, a link-species in thelineage from Koreanaia to Wakinoa. If
Wakinoa is considered as one of the subgenera of Trigonioides (OTA, 1975;
HAY AMI, 1975), it is reasonable to treat
Koreanaia also as another subgenus of
Trigonioides.
Subgeneric diagnosis (emend.)-Hinge
plate moderate in breadth, provided with
opisthocline pseudocardinal and posterolateral teeth; the pseudo cardinal ones
two or three in left valve, two in rightvalve, and the postero-Iateral teeth twoin left valve, one in right valve. The
hinge teeth typically lamellar but may

Trigonioides (Koreanaia)
bongkyuni, sp. nov.
PI. '2.7, Figs. 1-12; Text·fig. 3

Etymology- The specific name is dedi.
cated to Professor Bong Kyun KIM of
the Seoul National University who has
contributed much to the paleontology of
Korea.
Material-Holotype (KPE 2190, PI. 27,
Fig. 9) and forty six para types (KPE
2180-89, 2191-2226), collected from ahorizon in the lower part of the Yeonhwadong Formation, Nagdong Subgroup,
Gyeongsang Group (ColI. S.Y. YANG).
Description-Shell medium in size
(about 10-60 mm in length) generally
suboval or subquadrate in outline subequilateral and equivalve, moderate ininflation; anterior margin well rounded,
posterior one rather straight, ventral
margin broadly arcuate; ratio of L/H
about 1.3; test of moderate thickness;
umbo slightly prosogyrous,· placed atabout two-fifths of the shell length fromthe anterior extremity, projected slightly
above. the hinge line; escutcheon andlunule indistinct.
Surface ·ornamented with V-shaped
ribs in the median part and reversed
V-ribs on both of the anterior and theposterior sides. The angles of themedian V-ribs about 30-45 degrees andthose of the reversed V-ribs on both sides
about 50-60 degrees. The line linking
the apices of the median V-ribs prosocline,
forming about 80 degrees with the ventral
margin. The ribs and grooves on theposterior half stronger and wider thanthose on the anterior half; the former
ones run downward and gently curved
forward, while the latter ones run rather

228

Seong Young YANG

interval and prominence. Posterior ridge
running from the umbo to the posteroven tral corner.
Hinge plate IT_oderatein breadth, provided
with pseudocardinal and postero-Iateral
teeth; the pseudocardinal ones two on eachvalve, the postero-Iateral ones one onright valve, two on left valve, forming
the following dental formula;

3

5
4

PIII

2

PII

PIV

where 5: narro w and elongated with finetransverse crenulations on the ventral (lower )side onl y, pa rallel to the antero-dorsal
marg in,3: stout and high , with fine transverse crenulations on both sides, subpara llelto the anterodorsal margin ,Pill : narro w and elongated, w ith
ver y fine trans verse crenulations on bothsides, pa rallel to the postero-dorsal margin,
4: stout and high, with fine trans ..
verse crenulations on both sides, parallelto the antero-dorsal margin,
2: narro w and low, with fine transverse crenulations on dorsal (upper) sideon ly, subparallel to the antero-dorsal ma rgin,
PlI : narrow and elongated, w ith ver yfine trans verse crenulations on dorsal side
onl y, parallel to the postero-dorsal margin,
PlY: narro w and elongated, more orless lower and shorter than PlI, with ver yfine trans verse crenulations on ventral side
only, parallel to the postero -dorsal margin.
T ext -figure 3_ T rigo nioides (Koreanaia)
bongkyuni, sp _ no v . a: surface ornametation a nd th e outline of left val ve, b:internal structure of right va lve, c : internal structure of left valve. The sculpture
impressed on the internal surface is pro babl y due to the erosion of the inner la yer.

straightly downward. The median ribs
number more than 13 in the anteriorbalf and 9 in the posterior half of thelarge specimens. The whole surface
ornamented also with fine numerous
concentric gro w th-lines of irregular

Two adductor scars subequal in size;
anterior one semicircular, strongly impressed, accompanied with a minutedistinct pedal scar; posterior one sub~ircular and larger, but not so distinct_
The internal mould provided with im pression of V-shaped ornaments on theflank and with crenulations around theventral margin. Umbonal cavit y moderately deep_
Ob se1-vation- The holotype (KPE 2190)
is an ex ternal mould of right val ve_
The para t ypes are also external or inter-

710.

New bivalves from Gyeongsang Groupnal moulds. The tests were mostly
dissolved out. The internal structures
can be observed on some internal moulds.
Among the type-specimens, seven areconjoined, twenty four are right valves
and fifteen are left valves. The specimens at hand are mostly deformed tosome extent. Besides the type-specimens,
many fragmentary specimens werecollected.
Occurrence- The specimens describedhere were collected from the black shaleatWeolmagdong,
Ssangrim-myeon,
Goryeong-gun, Gyeongsangbug-do, Korea(see Text-figure 1). The black shale
contains abundantly the following
molluscan species besides the described
one and fragmental remains of plants.
Nippononaia ryosekiana (see YANG, 1978a)
Nagdongia cf. sod YANG
Pseudohyria sp. (described below)
Micromelania? katoensis SUZUKI
Viviparus sp.

Measurements (in mm)Length

HeightRight valve (KPE 2180)
15.3*
56.2+
Left valve (KPE 2182)
Left valve (KPE 2183)
17.0+
Right valve (KPE 2184)
28.7+
Right valve (KPE 2185)
25.9+
Conjoined valves (KPE 2187) 57.6
33.9
Right valve (KPE 2189)
Right valve (KPE 2190) * 56.6
Left valve (KPE 2192)
38.8+
Right valve (KPE 2202)
43.4
Right valve (KPE 2220)
10.8

13.1+
42.9+
9.6*
22.2
19.0+

Specimens

24.2+
38.1+
31. 3
32.3+
6.3+

* holotype
Comparison-The present species issimilar to Koreanaia cheongi YANG,
1976 in the surface ornamentation andoutline, but its ribs and grooves aremuch stronger and wider than those of
the latter. The subradial ribs of thepresent species number about 13 in theanterior half and 9 in the posterior,

229

while those of K. cheongi number 17 in
the anterior half and 13 in the posterior.
Above all, the hinge teeth of the present
species are clearly crenulated, while
those of K. cheongi are not crenulated,rather lamellar. The crenulations of thehinge teeth are quite similar to those of
Wakinoa wakinoensis, but the surface
ornametation distinctly differs from thatof the latter. In short, the present
species may be comparable with Wakinoa
in the hinge while it resembles Koreanaia
in the surface ornamentation, especiallyin the large angle of the V-sculptures.
In other words, the present species belongs
neither to typical Wakinoa nor to typical
Koreanaia. But it is rather reasonable
to assign the presen t species to one of
the two subgenera than to propose
another independent genus or subgenus.
In this case it is practically more convenient to classify the fossil species on
the basis of the surface ornamentation
rather than the internal structures forthe future identification.
Hoffetrigonia diversicostatus (HOFFET,
1937) and H. robusta (KoBAYASHI, 1968)
are similar to the present species in thelarge angle of V-sculpture on the mediansurface, but differ in their opisthogyrous
umbo, finer subradial ribs on the anterior
half and stronger inflation.
If the phylogenetic series of KoreanaiaWakinoa-Trigonioides (s. s.)-Kumamotoa
is assumed (OTA, 1963; HAYAMI andICHIKAw A, 1965; and YANG, 1976), thepresent species can be inserted between
K. cheongi and W. wakinoensis.
Subfamily Pseudohyriinae
KOBAY ASHI, 1968
Genus Pseudohyria MACNEIL, 1936
Type-species - Pseudohyria
MACNEIL, 1936

gobiensis

Seong Young YANG

230

Pseudohyria matsumotoi, sp. nov.
PI. 28, Figs. 1-8, Text-fig. 4

Etymology- The specific name is dedicated to Professor Tatsuro MATSUMOTO
of the Kyushu University who has greatly
contributed to the Cretaceous stratigraphy.
Material-Holotype (KPE 2163, PI. 28,
Fig. 1) and twenty eight paratypes (KPE
2151-62, 2164-79), collected from thelower horizon of the Yeonhwadong
Formation, Nagdong Subgroup, Gyeongsang Group, Korea (ColI. S.Y. YANG).
Description-Shell fairly large in size
(about 60-85 mm in length), trigonallysuboval or suborbicular in outline, fairly
inflated; subequilateral and equivalve;anterior margin well rounded, posterodorsal one rather straight, postero-ventral
corner rather angulate, ventral margin
broadly arcuate; ratio of L/H about 1.2;
umbo fairly high and prominent, slightly
prosogyrous, situated nearly centrally,
escutcheon and lupule indistinct; test
moderately tbick.
Surface ornamented with radial costae
and concentric growth-lines; the costae
indistinct near the umbo and on theanterior half, but becoming graduallyprominent toward postero-ventral side.
The costae on the postero-dorsal periphery
being widely separated tangentially fromthe posterior ridge. The radial costae
number 13 or more. Posterior ridge
fairly prominent.
Hinge plate moderate in breadth,provided with opisthocline pseudocardinalteeth and postero-Iateral teeth; the pseudocardinal ones three or four on rightvalve, three on left valve, the posterolateral teeth one on right valve, two on
left valve, forming the following dental
formula:
j5t

3

1a

1b

PIlI

4 ---2--1'a --- ~PIC --P"iV

where 5: narrow and elongated, parallel tothe antero-dorsal margin, occasionally indistinct,
3: stout and high, subparallel to theantero-dorsal margin,
1a: low and short, immediately below
the umbo, nearly vertical,
1b: low and short, smallest in theright valve, immediately below the umbo,
nearly vertical,
PIlI: distinct and elongated, parallelto the postero-dorsal margin,
4: stout and prominent, parallel to theantero-dorsal margin,
2: stout and high, subparallel to theantero-dorsal margin,l'a: low and short, nearly vertical,
PH and PIV: narrow and elongated,parallel to the postero-dorsal margin.

These hinge teeth neither crenulated nor
striated, but rather lamellar.
Two adductor scars subequal in size;
anterior one semicircular, strongly
impressed, accompanied with a minutebut distinct pedal scar, posterior one
subcircular and larger, but not so
distinct. The internal mould provided
with impression of the surface radial
costae on the flank, especially distinct
on the posterial part. Ventral crenulation on the inner side not so distinct.
Umbonal cavity moderately deep.

Measurements (in mm)Specimens

LengthHeightLeft valve (KPE 2151)
Right valve (KPE 2152)
Right valve (KPE 2153)
Right valve (KPE 2154)
Left valve (KPE 2160)
Left valve (KPE 2163) *Left valve (KPE 2166)
Right valve (KPE 2174)

67.7+
30.1+
75.5+185.5+
80.2+
69.3+
12.0+
65.1+

58.3+
26.4+
60.6+162.2+152.7+
10.9+
55.7+1-* holotype
Observation- The holotype (KPE 2163)
is an internal mould of left valve.
Many of the other specimens are also

710. New bivalves from Gyeongsang Group

Text·figure 4. Pseudohyria matsumotoi,
sp. nov. a: surface ornamentation and out·line of left valve, b: internal structure ofright valve, c: internal structure of left
valve.

internal or external moulds and fragments. Thererefore, the description is
supplemented by the para types.
The immature small specimens are
generally suborbicular in outline, but
gradually become trigonally suboval withgrowth. The posterior costae or plications are not distinct in the small

231

specimens but become distinct withgrowth.
Occurrence-Same as described above(Koreanaia bongkyuni).
Comparison-At a glance, the present
species looks similar to some species ofPlicatotrigonioides from U.S.S.R.(MARTINSON, 1965, pi. 3, fig. 6) and from Thailand(KOBA YASHI, 1968, pi. 20, fig. 1) in thetrigonally suboval outline and surface
ornamentation. But those species are
generally ornamented with rather strong
costae nearly on the whole surface, andthe costae on the postero-dorsal partstart 9.irectly from the last posterior
radial. costa which runs from theumbo to the postero-ventral corner.
The ventral crenulation on the inner
margin is rather regular and subquadrate
in that genus (MARTINSON, 1965, pi. 6,
fig. 2) unlike other trigonioidid species.
The present species is very similar to
Pseudohyria
cardiiformis ferganensis
MARTINSON in the surface ornamentationand internal structures. But in thelatter the radial costae climb up to near
the umbo, and are well developed evenon the anterior half. So far as theillustration is relied upon (MARTINSON,
1965, pi. 2, fig. 2), P. c. ferganensis
possesses two or three pseudocardinalteeth on the right valve, while thepresent species possesses three or four
ones on the right valve. With respect
to the surface ornamentation, the present
species is rather similar to P. d. cardiiformis (MARTINSON, 1965, pI, 2, fig. 4) from
U.S.S.R., but the latter is more elongatedlaterally, and not so high.
Remarks-Many species referred,to thegenus Pseudohyria have been reported
from Southeastern U.S.S.R. and China.
They are generally of upper Cretaceous
as illustrated in Table 2, while thepresent species is probably of lower
Cretaceous (see YANG, 1978b).

Seong Young YANG

232

Table 2. Stratigraphic occurrences of Pseudohyria spp.
(original data after MARTINSON, 1965, 1969; Ku, 1976)

Pseudohyria SPECIES NEOC. APT. ALB. CEN. TUR. SAN.-DAN.
P. javanica
P. babatagensis
c:::: P. rnujanica
P. plicatensis
If) P: kysyl kumaensis
P. k. aralica
If) P. ferganensis
P. mongolensis radiatusP.
tachtamyshensis::>
P. gobiensis itemirica
P. triangularis
P. tuberculata« P. obliqua
Z P. cardiiformis- P. gobiensis:c P. sinkiangensis
P. aralica
U P. songhuaensis~ P. matsumotoi, sp. nov.

.-_.
.-_.
. .

__ .
__
.---

.

.

.--.

.--.

.--.--.
.--.
._-_.

-

K

1

·--K

2

-

Explanation of Plate 27
Figures 1-12. Trigonioides (Koreanaia) bongkyuni, sp. nov.
1. Left valve (KPE 2197), internal mould, la; side view, showing the impression of thesurface ornaments, Ib; dorsal view, showing the crenulated hing teeth.
2. Left valve (KPE 2182), internal mould, side view, showing the crenulation on theantero·ventral margin, the impression of V-shaped ornaments on the posterior flank, the muscle
scars and the crenulated hinge teeth partly, the postero-ventral part broken out.
3. Right valve (KPE 2220), internal mould, showing the impression of V-shaped ornaments and the hinge teeth, immature specimen. x 2.
4. Left valve (KPE 2186), internal mould, showing the crenulated pseudocardinal hinge
teeth and the muscle scars.
5. Left valve (KPE 2191), external mould of the postero-dorsal part.
6. Left valve (KPE 2192), external mould, showing the crenulated pseudocardinal hinge
teeth.
7. Right valve, clayey cast of the external mould (KPE 2184).
8. Right valve (KPE 21948), antero-dorsal part broken out, 8a; external mould, 8b;
clayey cast.
9. Right valve, clayey cast of the external mould (KPE 2190), holotype.
10. Left valve (KPE 2196), external mould, strongly compressed laterally.
11. Right valve, clayey cast of external mould (KPE 2188).
12. Conjoined valve (KPE 2187), external mould, antero-dorsal part broken out, 12a;clayey cast of right valve, 12b; clayey cast of left valve.
All figures are approximately of natural size, unless otherwise stated.
Loc.: Weolmagdong, Ssangrim-myeon, Goryeong-gun, Gyeongsangbug-do, Korea (see Text-figure1) •YANG:

New bivalves from Gyeongsang Group

Plate 27

710.

New bivalves from Gyeongsang GroupThe hinge teeth of the upper Cretaceous species of Pseudohyria, that is, P.
aralica, P. tuberculata, P. cardiiformis
and P. aff. gobiensis, are more or lessdistinctly crenulated and are similar to
those of Wakinoa and Plicatounio, butsomewhat different from the regularly
crenulated teeth of the species of Trigonionioides (T.) and Kumamotoa. Up tonow, Pseudohyria is first found fromthe Lower Cretaceous formation in Far
East Asia, and the hinge teeth of P.
matsumotoi are not crenulated but lamellar
as described above. As the phylogenetic
relation can be read in the hinge teeth
in the series Koreanaia- W akinoa-Trigonioides (s. s.)-Kumamotoa, a similar transformation of hinge teeth may be expectedin the phylogeny of the Pseudohyriinae.
References
CHANG, K. H. (1966): Stratigraphy and sedi·mentation of Nagdong Subgroup (Lower
Cretaceous), Kyungsang province, south·
ern Korea. Jour. Ceol. Soc. Korea, vol.
2, no. 1, p. 17 -5l.
(1975):
Cretaceous stratigraphy ofsoutheast Korea. ibid., vol. 11, no. 1, p.
1-23.
CHOI, S. O. and KWON, Y. I. (1970): Explanatory text of the geologic map of
Gujeong sheet (1/50,000). Ceol. Surv.
KOlea. Seoul, p. 1-9, pis. 1,2.
Cox, L. R. (1952): Notes on the Trigoniidae
with outline of a classification of thefamily. Proc. Malac. Soc. London, vol.
92, nos. 2-3, p. 45-70, pis. 3-4.
HA Y AMI, I. (1975): A systematic survey ofthe Mesozoic Bivalvia from Japan. Univ.
Mus. Univ. Tokyo, Bull. 10, p. 1-228, pis.
1-10.
- - and icHIKAWA, T. (1965): Occurrenceof Nippononaia ryosekiana from Sanchu
area, Japan. Trans. Proc. Palaeont. Soc.
Japan, N.S., no. 60, p. 145-155, pI. 17.
KOBAYASHI, T. (1968): The Cretaceous non·marine pelecypods from the Nam Phung233

Dam site in the northern part of the
Khorat Plateau, Thailand with a note on
the Trigonioididae. Ceol. Palaeont. S.E.
Asia, vol. 4, p. 109-138, pis. 20-23.
- - and SUZUKI, K. (1936): Non·marine
shells of the Naktong.Wakino series.
Japan. Jour. Ceol. Ceogr., vol. 13, nos.
3-4, p. 243-257, pis. 27-29.
Ku, C. W. et al. (1976) : Fossil lamellibranchsof China. Nanking Inst. Ceol. Palaeont.,
Acad. Sinica, p. 1-522, pis. 1-150.
MACNEIL, F. S. (1936): Notes on Pseudohyria
gobiensis gen. et sp. nov. from the Iren
Dabasu formation at Iren Dabasu, Inner
Mongolia. In F.R. MORRIS: Central Asia
in Cretaceous time, Bull. Ceol. Soc.
Amer., vol. 47, no. 9, p. 1477-1534, pis.
1-2.
MARTINSON, G. G. (1965): Biostratigraphy
and fauna of Cretaceous continental
deposits. (in Russian) .
Sci. Acad.
U.S.S.R., p. 101-152, pis. 1-11.
- - (1969): Biostratigraphy and fauna of
the Cretaceous continental system in
Tadzik basin, Kizilkum and along theriver Chura in the vicinity of Taskhent.
ibid., p. 18-50, pis. 1-6.
OTA, Y. (1963): Notes on the relationshipof Trigonioides and Plicatounio, nonmarine Mesozoic bivalvia from eastern
Asia. Ceol. Rept. Hiroshima Univ., no.
12, p. 503-512.
- - (1975): Notes on the genus Trigonioides(Bivalvia). Bull. Fukuoka Univ. Educ.,
vol. 24, pt. 3, p. 79-98.
SUZUKI, K. (1943): Restudy on the non·marine molluscan fauna of the Rakuto
series in Keisyo-do, Tyosen. Jour. Sigenkagaku Kenkyusyo, vol. 1, no. 2, p. 189219, pis. 14-19.
YABE, H. (1905): Mesozoic plants from
Korea.
Jour. Coli. Sci., Imp. Univ.
Tokyo. vol. 20, no. 8, 1-59, pis. 1-4.
YANG, S. Y. (1972): On the distribution ofreddish beds of Hasandong formation innorthern part of Daegu-W aegwan area.
Theses Coli. Crad. Sch. Educ., Kyungpook
Univ., vol. 3, p. 77-9l.
- - (1976): On the non-marine molluscan
fauna from the upper Mesozoic Myogog

234

Seong Young YANG

formation, Korea. Trans. Proc. Palaeont.
Soc. japan, N. S. no. 102, p. 317-333, pis.
33-34.
- - (1~78a): Ontogenetic variation of Trigonioides (s.s.) paucisulcatus (Cretaceous
non-marine bivalvia). ibid., no. 111, p.

333-348, pis. 45-46.
- - (1978b): On the discovery of Nippononaia ryosekiana from Gyeongsang group,
Korea. jour. Geol. Soc. Korea, vol. 14,
no. 2, p. 33-34, pI. 1.

Ancheon *JII, Anlimdong ***foJ,
Banyaweol ~:eiYJ,
Bulgugsa {blE~,
Chaeyagsan:f*~W,
Chilgog ~:fr,Daegu *Ji'~,
Dongmyeong JR:!Jij,Geoncheonri ¥l;JII11,
Goryeong ii1li~,
Gujeong Atr,
Gyeongsang ~~,Habcheon Il*JII,
Hagbong .~,Haman ~*,
Hasandong ~WfoJ,
Jinju wm,
Jusasan *Ti'JiW,
Myogog 91l:fr,
Nagdong mJR:,
Paldal Ait,
Sinla ~lI,
Ssangrim-n.yeon ~**ITii.
Waegwan ~U!i;
Weolmagdong YJ :iJfoJ,
Yeonhwadong ~fEfoJ.
~lErml.j';1fiJi!fUHE::::ttJ'l.~:fiI!ft:Ot;::'?"'-C:~j';1fiJi!fUJilrmlJi!fL'ib7.> ~fE11l!1Ji!ftpt> HE

ill L.. t.::. ilikf*lIJiJilmft:o q:,::::ttJ'l. 2 ~f1~~~"t 7.>. -t ~ q:"

Trigonioides (K oreanaia) bongkyuni, n. sp. It-t~~iHi~Mlilt Koreanaia ~~~~.J~lt Wakinoa ~~5FL..-C"'7.>.
;:.;h t> ~M~ CJi!f1f:~fj{J~f*tJ, t>~ljwr L.. -C, ;:. ~~:fiI!lt!l4~fj{JtJ: Koreanaia tJ't> Wakinoa
i t.::.lt Trigonioides (s.s.) t;::~ft"t 7.>*7U~q:,r,,'~c fW~ ~;h7.>. Pseudohyria matsumotoi, n. sp. It-t~Ji!f1f:~fj{JOOf*~~.::t -c, Lf"iL'7~7*~tJ't>¥jH!r~;ht.::. Pseudohyria
spp. ~m9i;tuJ:7.>PTIi~1i.tJtib7.>.
~ ffi.

*

Explanation of Plate 28
Figures 1-8. Pseudohyria matsumotci sp. nov.
1. Left valve (KPE 2163), internal mould, holotype. la; side view, showing the pseudocardinal teeth, the muscle scars, and the impression of radial plicae on the posterior part.
Ib; dorsal view, showing the hinge teeth, lc; rubber cast, showing the internal structures.
2. Right valve (KPE 2169), internal mould, posterior part broken out, 2a; dorsal view,
showing the pseudocardinal hinge teeth, 2b; rubber cast, showing the pseudocardinal teeth'and the muscle scars.
3. Left valve (KPE 2166), internal mould, showing the hinge teeth and the muscle scar,
immature specimen. x 1.6.
4. Left valve (KPE 2152), internal mould, showing the pseudocardinal tooth.
5. Left valve (KPE 2173), internal mould, dorsal view, showing the hinge teeth.
6. Left valve (KPE 2157), posterior part only, 6a; external mould, showing the radialplicae on the posterior part, 6b; clayey cast.
7. Left valve (KPE 2151), internal mould, showing the hinge teeth, the muscle scar andthe impression of posterior plicae.
8. Right valve, clayey cast of KPE 2153, showing the radial plicae antero-dorsal andpostero-ventral parts broken out.
All figures are approximetely of natural size, unless otherwise stated.
Loc.: Weolmagdong, Ssangrim-myeon, Goryeong-gun, Gyeongsangbug-do, Korea (see Textfigure 1).

YANG :

New bivalves from Gyeongsang Group

Plate 28

235

PROCEEDINGS OF THE PALAEONTOLOGICALSOCIETY OF JAPAN

~

~

~c

•

B *ti~¥J.J~~~ 124@]{7IJ~ft.1979~10Jl20 B t:.
~ti~*~w.~$ t:.:to~ ,"( Mil ~tLt.: (~~~74
~)o

1m A

~

iJil

i'¥tdIIIWf$ft~-£~ itiIEm:w- #ilI fl) 15 W('lljJa~1r.

15Jfi!1/'f ............................ i1!lB35!:AA
Geological age of the N obori Formation,
Shikoku, as viewed from calcareous nannofossil evidences .......... T. TAKAYAMA:lfH;Jfi!I • i1!liliJfi!l .................... ;f".kilUl~7C...... ~;gtiRf!!WlJfi!lfffl)Jt~1r.15t:."?~'"(~i¥J~t-t......................... ,1H~m

1r.15Jt~fl) f*~)ffy~ ~ {- fl) ~UIB)ffy ~ fl) ~f*t:.~i" 7.>~~ : 2 ~~fl)~t(; ............ /N;f~Eocene planktonic Foraminifera from Chichijima, Ogasawara (Bonin) Islands ....... .
...... Y. TAKAYANAGI and T. KATAYAMA*3ft$fJ!ljfl) 9=t;M9=t~ti!:t:.:toft 7.> JrEfl1r11.!Rff~~ti}jj!mfl)ft£ilt:."?~'"( ............ WB3 :w
m*!Jjld)'l?ft.l:.lb"(~Ji ~tLt.:,,?~,"(*

Miogypsina t:.

......•...........••.....• ;f".k1LIE~•

t$-'~ili~-'*~~~'ilI~ ~A new Chlamys from the Shitakara Formation of the Urahoro Group, Kushiro
coal field, eastern Hokkaido .... Y. HONDA~.Jfi!lfl)Jfi!I&·ti~¥J.J~I-JrE~~15~~fl)*.................. {ii:~~!Jj
tl*JIIJfi!1ff&:fl)/¥-iiM:J'l.M1r.15 .......... ~B3 ~i1!lWf B * 9=t~ti!:fj(f*lIffJ¥J.J1r.15 fl) 2 • 3 fl) r~'JI:!i~ <t:. ti:l1!!w.t:.~f* L-"( .......... *:i.JII 1$'::::"
3fi¥Jft£1r.t:."?~'"(

Indo-Western Pacific species of Melaxinaea
IREDALE, 1930 ............ A. MATSUKUMA
Fossil species of Clypeaster from japan ..
. . . . . . . . . . . . . . . . . . . . . . . . . . .. A. MORISHITA**~Y*?Aff1~~~Wfl)m~~~~fl)~Bi}~.......... ~J: J:!t. iliB3~~~' ~B3I1i±

Preliminary

reportontheecologyi'fift$M~~.~Y~-fl).ff~m~i~V-~-fl)~~~{-fl)M~M~ff~W.~~fl)~ffl. ... ~1i$~!Jj· ~B *i'fifrd7¥J:$~~:W-fl)rlNJm!;f;~1r.15 {-fl) 3~~~Afl)~~~*Jt~Jfi!I/'f~Jt~4~fl)~M

Possible feeding habit of Nautilus pompilius
from the viewpoint of anatomy and its
impication for cephalopod paleobiology ..
" Y. FUKUDA, K. TANABE and Y. KANIE
Implosion of living Nautilus test underincreasing pressure: its bearing on cephalopod paleobiology .......... Y. KANIE,
Y. FUKUDA, H. NAKAYAMA, .K. SEKI and
M. HATTORIof

Nautilus pompilius in the Philippine Seas.... ............ K. TANABE and Y. KANIE..

~f:iJj. 9=tili~1!J.I • ~nI*:J'[;

Shell growth of living Nautilus in captivity. . . . . . .. H. HIRANO and jECOLN members
SEM observations on siphuncles in ammonoids and living chambered cephalopods:
microstructures and their functional significance ................................. .
.. I. OBATA, K. TANABE and Y. FUKUDA
Early jurassic plants in japan. Part 1:
Equisetales .... T. KIMURA and M. TSUJII
Cuticular study on the Ginkgo leaves fromthe Upper Cretaceous Omichidani Formation, Ishikawa Prefecture, japan ....
................ T. KIMURA and T. OHANA=¥Jli(itilEiIt¥J.Jfft:.&: L- t.: Pterophyllum ~t:. ,,?~,"( ................................ ;f".k )~Jf;;~....
.............. ili~Mi;Jc· ilUlB31ft5!: • illB3$R]~ll B ,!i!;:l1!!JlilGt:.&:i" 7.> PR1r.;fit1r.15t:. "?~ ,"(A study of the pennatae trigoniids fromJapan ........................ M. TASHIRO~7J+*~p~AJfi!lfffl).::::..tlcJ'l.1r.15......... .

........................ l¥~<xn~· B3~IEZ
On a new bivalve genus, Nippononectes,
from the Cretaceous of japan ......... .
.............. M. TASHIRO and K. NAKANO
Bl!l!*1i\1lfflrmJfi!lfffl)~J'l.1r.15t:."?~'"( ........
. ....................... :!ii1:*1!fi~.:!Ei~~~

Early Cretaceous Gastropoda from the
Choshi district, Chiba Prefecture, Central
japan ........... . T. KASE and H. MAEDA
Upper Cretaceous ammonites from theIzumi Mountains, Southwest japan ..... .

236........ T, MATSUl'viOTO and Y. MOROZUMI~~!llrfQ)ggn-t*Q):liXM~t.::."?\""{....... .
. . . . . . . . . . . . . . . . . . .. '*'t!!:J!i~!X t!~ • '*')11 ~==.
~71* Q) ==.~* :to .t If ='- 7 * Q) :liX1tY:~ t.::. "? \, ,"(. .. .. .. ... '*'t!!:J!i~;xt!~. tfJJtJt==. • ggMWlr
Late Permian Radiolaria from the Tamba
Belt in Osaka Prefecture, Japan ....... .
........ K. NAKASEKO and A. NISHIMURA
Mesozoic Radiolaria from the Hida-Kanayama area, Central Japan ............. .
........ S. MIZUTANI, Y. OKAMURA andK. SHIBATA
Fusuline biostratigraphic zonation and correlation of the Permian limestone groupin the Abadeh region, Central Iran ..... .
•...... .. .... ... K. ISHII and Y. OKIMURA
Outline of the Carboniferous trilobites ofJapan ... •T. KOBAYASHI and T. HAMADA

Neopetalodus, a new genus of Ellasmobranchii from the Permian Akasaka Limestone, Japan .. M. MURATA and T. UYENO,;; Iv Iv *[1. r ~ ? -t ? i? <J 7t~11::P~i: ..... .

................................ ~M:IltzJl;lJ
i!:i~~liJf~pJi~i!i~&I!~~Ji!Jjtl£~
lllJ!i~4W

c l'iim!tk~ ................. .IhlR f!

fili{l::Plilf~tJ'I?~,?.::. C
J!i~4WliIf~iYTt.::.~tr.::. C............ ~;e.

.............. *MWli$

JJ

J!i ~ 4WliIf~iYT"" Q) WH~ ................ B311r~J
J!i~4WliIf~iYTt.::.M#ii" 7.J ~ Q) tJlIItm-Jjj(;· t'lIlN:Wl~
J!i~4WliIf~iYTl;t\,'tJ't.::.~ 7.J~ ~tJ, •.••. .INJHi!'~
J!i~4WliIf~iYTt.::.~tr.................. ilM'i-1J1JZ

J!i~fft!llb4W~Q)ft*RitJ, I? J!i~4WliIf~iYTt.::.~tr.::. C.................................. *~mz

J!i1ffft!llb4W~ c J!i~4WliIf~iYT.......... ~JiIi\j~~flM
1980~~il; • ~il;

$t

illl

~ 125 @I

~

~

{1U

~

:til!

*
*

M

fl

BtIt~$~~ma~1980~ 1 R25' 26a

19791j:.uR 25 a~

1980~6 R29a1980~4 R29a

6R29a (a) (7)~125@1{11Jil;-ell::--:/,f-;/ryA rgg7J+1f1i(7)&:.~i¥=~C7)m:ljU:4-~C7)rR~JmR.U '/J~,
30a (m t~ll~~!JiHt;:JII:t1l!1J~(7)~~'/J~7~~h"(I,'i!>.

6R

04Hi~f,!;j!9'l:DiJJ~(7)~~milt~ '? \" "C*~~J;l7'j-(7)~fi~f,!;j!9'l:DiJJ~ .1!bnJ(;~tJ: ct~.tt.~~hi!>1J-e~~mil~~'J!ci'"i!>~~, "it.:~fi1it(7)~fm~C I..- "C~~tJ:1J~~~ J: I) mil I..- "CW\I..-\"c1ri~~hi!>:Ijj~ll, tJ:i!>~1t(7)~~~¥f;$, if!:
illl*~Jt!!~~~*~IHJlII~~3U -e:t,;$!:lrf~ \". *il;c I..- "Cll1t(7)~~il;t~~f1i"::>t.:J:, ml!HR:/sb"ii'".
tJ::t,;*~il;t~~1*(7)i*\"!9'l:DiJJ~ ·1!bnJ(;~c I..-"Cll, iWJa~VJij~DiJJ~, =:~Mffii3?t,\:f4~9If5e1!bnJ(;~, ~~~I),1itcl..-"C~iWJa~~.1it~c~~l)ti'".
O{~:ti29~ (1lB;frl54~10R25a §err, 2000FJ) '/J~fUrr~ht I..-t.:. 1lB;frl54~ 1 m~m/lUJ-errtJ:bht.:::z P "fry A r@l~:l<\tJ:f:;(7) J!:tIl!iJ, ~.;z,..t.: a *:1"0 J: L)(jl[~:tIl!C7) s1lli:~{tEJ t~'/J'A.,i'" i!> !i ;/:;t- Iv~Jt, {tE(7)-ut9lt,-1 :/ ~:;t-::-- a :;t- IH ,f- - r tJ: c'/J~1!!I:'!lit~mJ!lt~h "C\" ti'".
{tEJ 111 ffit~ c (7)JlIji7H \"t.: I..- "ii'"'/J~,<!f. <*

r~~7t':J~~t\lt~~~ I..- "C\"t.:t-: ~, §err(7)'I$~:t,;* I) I..- "C, tt~~~t&\,' L "C\"t.:t-: <1J~;6~fifU-ei'".
~1ri~(7)1Jll, 11iJ~ ~~**:ge c *%t-:~iJ'~m7t0'/J,~§J3~(7)J:, "f~~:t,;$~.;z,.. "f~ \" •.
'T980 fJililflrm~*i1f~*~t*~llI!~ffll:tll!Jt~i1&:.4ifo~~~Jf<J{tEiUI~ffll (~ifgerr~

1 9 7 9 ~ 12 R 25 a(:JJ

1 9 7 9 ~ 12 R 30 a

~

ISS~

~

•

2.000 Fla*ii~~~~Jt Jj{ IK ~ &:. 2-4-16

JilU
rr

a*~~$$~:/~-Pl(~ if 00031-0204

116 %fJil-a17141)

(~

•

illS

~ JI( Jj{ 84780 11)
0 3 - 8 1 5 - 1 9 0 3)~'1ifJfinIE

~

~

~*

lOP .IilU~

Jfi! Jj{ m** .!Ii IK fl 3i ~t 2 / 13

~VJij~.(:JJJilUI*~~:f!:(ll illS

&"

EB

~

0 3 - 9 9 1 - 3 7 5 4)

Transactions and Proceedings of the PalaeontologicalSociety of Japan

December 30, 1979

New Series No. 116

CONTENTS
TRANSACTIONS
708. KOMURA, Seiichi: Eine neue Diatomeen-Gattung aus den oberneogenen
Koitoi Schichten, Tenpoku, Hokkaido ................................ 175
709. TASHIRO, Masayuki: A Study on the "Pennatae Trigoniids" from Japan .. 179
710. YANG, Seong Young: Some new Bivalve Species from the Lower Gyeongsang
Group, Korea . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 223
PROCEEDINGS .................................................................. 235