ISSN 0031-0204

a~"'~f.~~~~.:k. fz.'
Transactions and Proceedingsof thePalaeontological Society of Japan
New SeriesNo. 127

Palaeontological Society of Japan
September 30, 1982

Itaru HAYAMI and Ikuw o OBATA
Co-Edito rs
Associate editors T er uya UYENO and Tomow o OZAWA

Officers for 1981--1982
President:

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The fossil on the cover is an adult example (T . T AKAHASHI colI.) of

Mi kasaites orbicularis MATSUMOTO (subfam ily Marshallitinae, famil y
Kossmaticeratidae) from the Lower Ceno ma nia n (Cretaceous) of theMikasa area, central Hokkaido. (photo by M. NODA, natural size)

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Trans. Proc. Palaeont. Soc. Japan, N. S., No. 127, pp. 357-363, pis. 57, 58, September 30, 1982

747. A NEW SPECIES ACESTA (PLICACESTA) WATANABEIFROM THE MIOCENE IN SOUTHWEST JAPAN*
MITSUO NAKANO**
Institute of Geology and Mineralogy, Faculty of Science, Hiroshima University,
Higashi-senda-machi, Hiroshima 730

KAZUO OKAMOTO
Laboratory of Geology, Faculty of School Education, Hiroshima University,
Shinonome 3 cherne, Hiroshima 734

Abstract. In this paper, the writers wish to add some notes on Acesta (Plicacesta)
from the Tertiary formations in Southwest Japan and give a new name, Acesta(Plicacesta) watanabei sp. nov., to Lima (Acesta) aff. amaxensis Yokoyama of
Okamoto and Nakano, 1967.

a new specific name, Acesta (Plicacesta)
watanabei sp. nov., to Lima (Acesta) aff.
amaxensis Yokoyama of Okamoto andNakano, 1967.
The writers wish to express theirsincere thanks to the late Mr. Genji
Watanabe of Oyabe City in Toyama
Prefecture and gentlemen of the Wanibuchi Mine, Showa Mining Company and
the Kagoshima Prefectural Culture Centre
for supply of the materials. The writers
acknowledge the kind helps given by
Professor Harold E. Vokes of the Tulane
University in Louisiana, Dr. junji Itoigawaof the Nagoya University, Dr. Yoshiro
Ueda of the Geological Survey of japan
at Tsukuba, Mr. Iwao Yamana of the
Tottori Prefectural Museum, Professor
Tadashige Habe of the Tokai University
at Shimizu, Professor Shozo Hayasaka of
the Kagoshima University and Professor
Shoji Fujii of the Toyama University.
This study was supported in part by

Introduction and Acknowledgments
Plicacesta Vokes, 1963 is a subgenus of
the genus Acesta Adams and Adams,
1858, and is well characterized by its
plica ted radial sculpture on the surface.
It is well represented by numerous species
from the Eocene to the Recent in the
North Pacific region.
It was mostprospered and widely spread from Burma
to Chikotka peninsula of East Siberia
through japan in the Miocene, but it was
declined in the Recent seas, where only
two species are known from japan andCalifornia as relics.
Recently, the writers had a good chance
to study many japanese fossils of Acesta(Plicacesta) from various localities. On
this occasion, the writers wish to add
some notes on Acesta (Plicacesta) and give

* Received September 10, 1981; read October
4, 1981 at Hiroshima.

** Deceased357

Mitsuo NAKANO and Kazuo OKAMOTO

358

Grant-in-Aid for Scientific Research from
the Ministry of Education, Science andCulture.
Notes on Acesta (Plicacesta)

Family Limidae Rafinesque, 1815
Genus Acesta Adams andAdams, 1858
Type species: Ostrea excavata Fabricius,
1779. Recent, North Atlantic Ocean.

Subgenus Plicacesta Vokes, 1963
Type species:

Lima smithi Sowerby,

1888. Recent, Japan.
Remarks :-In Japan the Tertiary limid
specimens under the name of L. smithi
or L. cf. smithi were reported andcollected from various localities by several
authors, such as Yokoyama (1925), Kuroda(1932), Uozumi (1962) and others, but mostof their specimens are not so wellpreserved in condition. As suggested byVokes (1963a, p.91), therefore, their morphological characters are, as a rule, unable
to be recognized from these specimens except Yamana's (Tot tori Prefectural Government, 1966, pI. 3, fig. 5; Yamana, 1969,
p. 6, fig. 1) and Okamoto and Nakano's
specimens (1967, pp. 189-190, pI. 21, figs.
la-b). L. cf. smithi of Yamana is closely
similar to the middle stage of L. aff.
amaxensis of Okamoto and Nakano (1967,
pp. 188-189, pI. 20, figs. la-b) in shellform and surface costation, and they areconspecific with each other. In essential
characters, L. aff. amaxensis is distinctivefrom the other members of Plicacesta
and, . therefore, this is possibly new toscience. On this occason, the writers
give a new specific name Acesta (Plicacesta)
watanabei sp. nov., to this form. L. cf.
smithi of Okamoto and Nakano has someresemblance to the Recent L. smithi inessential characters, but differs in having
large shell and wide and depressed
posterior auricle. In this respect, thisform is also new to science. However,more sufficient materials are necessary togive a new specific name exactly. Therefore, whether L. smithi was inhabited in
the Tertiary or not is a question.
The plica ted radial costation on thesurface is the most important characterfor the subgenus which comprises several
forms as listed by Vokes (1963a, pp. 9091; 1963b, p. 20). The following forms
may be added to this subgenus.
Acesta (Plicacesta) watanabei sp. nov. MiddleLate Miocene; Shimane, Tottori andToyama Prefectures, Japan.
Lima (Acesta) d. smithi Sowerby of Okamoto
and Nakano, 1967. Late Miocene; Hirata
City, Shimane Prefecture, Japan.
Lima takeyamai Ozaki, 1956. Middle Miocene;
Ibara City, Okayama Prefecture, Japan.
Acesta oyamai Kamada, 1973. Eocene; Iojimamachi, Nagasaki Prefecture, Japan.

This subgenus varies to a fairly wide
extent in surface sculpture and shellform. The shell size is fairly large inordinary species, but small in A. oyamai
and L. protosquamosa (Noetling, p. 1901,
114, pI. 3, figs. 10, lOa) and large in A.
watanabei sp. nov. The shell outline istriangularly ovate in many forms, butsomewhat trapezoidal in A. watanabei sp.
nov. and elongated ovate in A. oyamai.
The posterior auricle is broad but not
so well-defined from the main part ofthe body in many cases. It is, however,fairly distinct and depressed in L. amaxensis
and L. cf. smithi. The ribs on the surface
are fairly thick in ordinary species, but
broad and stout in L. sameshimai (Oyama
and Mizuno, 1958, p. 10, pI. 1, figs. 11, 12)
slender in A. oyamai and bi- or trifurcatedin L. takeyamai. Their number is as arule 40 to 50, but 16 to 21 in L. sameshimai

7.47.

Acesta (Flicacesta) watanabei from the Miocene

359

Pliocene• Miocene• Oligocene• Eocene

Fig. 1.

Locality map of the fossil Acesta (Plicacesta) species in Japan.

and about 35 in A. oyamai.
It is noteworthy that Lima (Acesta)
amaxensis Yokoyama of Monden (1960, p.
280, fig. 1) from the Tertiary or Quaternary tuffaceous sandstone layer at a cliff
near Irino, Kaimon-cho, Kagoshima Prefecture, Japan, is represented by a single
fragmental left valve specimen now
stored in the Kagoshima Prefectural
Culture Centre in Kagoshima City. This
form appears to be somewhat similar to
the typical form of L. amaxensis in-essential characters, but is distinguishable
from the latter in the nature of radialribs which are flat-topped on the anterior
fourth of the shell. In this respect, thewriters are of the opinion that it may bebetter to be treated as Acesta sp. There-

fore, it is obvious that the Eocene formation is not distributed in the Kaimon
area mentioned above.
Lima takeyamai Ozaki (1956, p. 8, pI. 2,
fig. 3) from a coarse-grained shell sandstone layer of the Middle Miocene Namigata Formation in Ibara City, Okayama
Prefecture, Japan, is, though imperfect,quite similar to Lima smithi Sowerby inessential characters. The ribs on thesurface of the to po type stored in the
Nagoya University are plicated and about
40 in number. The shape of ribs isbroadly round-topped in the latter, but it
is fairly sharp and narrow in the former
which has deeper grooves than those of
the latter. However, the ribs of L.
takeyamai soon become broad and round-360

Mitsuo NAKANO and Kazuo OKAMOTO

topped and bi- or trifurcated in the adultstage and grooves are broad. In thisrespect, Lima takeyamai Ozaki belongs tothis subgenus and is separable from LimasmithZ" Sowerby.
Dz"strZ"butz"on;-This subgenus may haveappeared in the Eocene of Japan, andwidely distributed in the Miocene fromBurma (L. protosquamosa Noetling, 1901)
to East Siberia (L. aff. goliath; Merklin,1954) through Japan. In the Recent, two
species, i. e. L. smithi and L. sphoni(Hertlein, 1963), are known as the relics
from Japan and California, respectively.

Description of Acesta(Plicacesta) Species

Acesta (Plicacesta) watanabei sp. nov.
PI. 57, Figs. 1a-b; PI. 58, Figs. la-b.

1962. Lima sp.: Yamana, Bull. Tottori Pre/.
Mus., No.1, pI. 2, fig. 1.
1966. Lima (Acesta) d. smithi: Tottori Pref.
Government, Expl. Text Ceol. Map.
"Tottori Pre/." (11100,000), pI. 3,
fig. 5.
1967. Lima (Acesta) aff. amaxensis: Okamoto
and Nakano, Trans. Proc. Palaeont.
Soc. Japan., N. S., No. 68, pp. 188-189,
pI. 20, figs. la-b.
1969. Lima (Acesta) d. smithi: Yamana,
Native Places and Sciences (Kyo do to
Kagaku) , Vol. 15, No.1, p. 6, fig. 1.
1976. Lima (Acesta) d. smithi: Tottori Pref.
Mus., Fossil Catalogue 2, p. 15, pI. 3,
fig. 1.
1977. Lima (Acesta) d. smithi: Yamana,

Bull. Tottori Pre/. Mus., No. 14, p. 14,
pI. 3, fig. 1.

Material ;-A fairly well-preserved left
valve specimen, holotype (Reg. No. GSEHOK-S001),.derived from the early Middle
Miocene Taisha Formation or Tadaura
Formation in Yuya-dani, Yokan, Taishamachi, Shimane Prefecture and a rightvalve impression cast, para type (Reg. No.
GSEH-OK-T003), from the Middle Miocene
YashiroFormationinNukakojima(36°41'54"N, 136°51'17"E), Oyabe City,
Toyama Prefecture. Besides them, thewriters observed several specimens from
the Middle Miocene Tochimoto Shale
Member of the Tottori Group in thesoutheastern area to Tottori City, Tottori
Prefecture.
Description ;-Shell of large size, opisthocline, somewhat trapezoidal to triangularly ovate and inequilateral exclusiveof auricles, a little higher than broad,gently convex from umbo to venter andfrom anterior to posterior; antero-dorsal
margin slightly concave and about a half
as long as the shell, sloped subverticallydownward; antero-ventral rounded but
somewhat subangulate at junction withantero-dorsal, passing gradually into
broadly arcuated ventral as can be judged
from the growth-lines; postero-dorsal
gently arched and almost a half of theshell length, forming an angle of about
120 degrees with the hinge-line which isnearly straight or slightly arcuated andabout a fourth of the shell length; umbo
prominent and sub central ; anteriorauricle, tiny, triangular, slightly produced

Explanation of Plate 57
Figs. la-b. Ace.ta (Plicacesta) watanabei Nakano et Okamoto sp. nov ................... p. 360
Ho!otype, side (la) and anterior (lb) views, xl
Fig. 2. Acesta (Plicacesta) sp. d. A. (P.) watanabei Nakano et Okamoto sp. nov ....... p. 361
Side view, 'x 1

NAKANOand OKAMOTO:

Acesta (Plicacesta) watanabei

Plate 57

747. Acesta (Plicacesta) watanabei from the Miocene

361

Table 1. Measurements (in mm), Acesta (Plicacesta) watanabei sp. nov.
Employed Aoki's method (1956).
Holotype (GSEH-OK-S001)
Para type (GSEH -OK - T003)

Heightca 132120+

and depressed; posterior one trigonal,
large but not so depressed and ill-differentiated from body of the shell; lunule
fairly large, cordiform and well excavated.
Surface ornamented with numerous,
fairly broad, round-topped plica ted radialribs with narrow and shallow grooves
except for the posterior and anterior
extremities where the grooves are broad
and about twice of the width of ribs; 6
or more on the antero-dorsal part nearlystraight or slightly curved anteriorly;
about 30 on the medial part of the shell
almost straight and somewhat flexiatedand rarely bifurcated but gradually
become thinner toward the posterior;some 5 on the rest of the shell almost
straight and rather thin; auricle andlunule provided with several radial ribs.
Growth-lines well developed on thewhole surface, especially on the ventral
and posterior extremities. Internally,
resilifer pit fairly large, triangular, anddirects forward.
Remarks:-The shell outline in theearly stage (less than about 30 mm nearumbo) is ovate, but it gradually changes
into trigonally ovate in the adult. The
surface in the early stage is sculptured
with flat-topped ribs with narrow grooves,
but the ribs gradually change into roofshaped through round-topped and thegrooves become very broad.
This species shows a certain degree ofthe variation in its shell form. The shellof the holotype is taller and moretriangular than that of paratype. Of theposterior auricle, it is straight and rather
short in the holotype but gently arcuateand broad in the para type. It is, how-

Width
126
130+

Obliquity
135+

1/2 thickness
ca 24
22

ever, fairly constant in number of ribson the body of the shell, and it is 41 or
so.
Comparison:- This is allied to Lima
amaxensis Yokoyama, 1911 from the
Eocene of Kumamoto Prefecture, but isdistinct in having more inflated ovate andlarge shell on which the posterior auricle
is not so well-defined as that of thelatter. Lima (Acesta) cf. smithi Sowerbyof Okamoto and Nakano (1967) from theUpper Miocene Wanibuchi Formation in
Shimane Prefecture is very close to thepresent form, but differs in the tall andlarge shell. This is similar to Lima smithi,Sowerby in the Recent from the sea
around Japan in the character andnumber of ribs, but the latter is easily
distinguishable from the former by more
ovate and smaller shell.
Occurrence and Lithology:-The holotype was found in a moderately brownto dark greenish gray lapilli tuff orvolcanic conglomerate layer of the Taisha
or Tadaura Formation. The paratype,with Doliocassis japonica (Yokoyama) and"Dentalium" sp., was collected from alight brown tuff bed of the Miyajima
Tuff Member of the Yashiro Formation.
This form is fairly abundant in a tuff
bed in the Tochimoto Shale Member of
the Tottori Group.
Acesta (Plicacesta) sp. cf. A. (P.)
watanabei sp. nov.
PI. 57, Fig. 2.
Compare :1962. Lima sp.: Yamana, Bull. Tottori Pre/.
Mus., No.1, pI. 2, fig. 1.

362

Mitsuo NAKANO and Kazuo OKAMOTO

1966. Lima (Acesta) cf. smithi: Tottori Pref.

Government, Expl. Text. Geol. Map.
"Tottori Pref." (1/100,000), pI. 3,
fig. 5.
1967. Lima (Acesta) aff. amaxensis: Okamoto
and Nakano, Trans. Proc. Palaeont. Soc.
japan, N.S., No. 68, pp. 188-189, pI.
20, figs. la-b.
1969. Lima (Acesta) cf. smithi: Yamana,
Native Places and Sciences (Kyodo to
Kagaku), Vol. 15, No.1, p. 6, fig. 1.
1976. Lima (Acesta) cf. smithi: Tottori Pref.
Mus., Fossil Catalogue 2, p. 15, pI. 3,
fig. 1.
1977. Lima (Acesta) cf. smithi: Yamana, Bull.
Tottori Pref. Mus., No. 14, p. 14, pI. 3,
fig. 1.
1982. Acesta (Plicacesta) watanabei sp. nov.,
Trans. Proc. Palaeont. Soc. japan, N.S.,
No. 127, pp. 360-361, pI. 57, figs. 1a-b;
pI. 58, figs. la-b.

Material :-A single, imperfect internalmould specimen (Reg. No. GSEH-OKS004) from the Late Miocene Wanibuchi
Formation in the southern area of Uchida(35°25'53"N, 132°45'04"E), Kawashimomachi, Hirata City, Shimane Prefecture.Remarks:- This form is, though imperfect, fairly large in size and its outline
is triangularly ovate to ovate as can be
judged from the growth-lines. The
surface is provided with 40 or so, radialribs. In this respect, this form is quite
similar to the middle stage of Acesta(Plicacesta) watanabei sp. nov. in essential
characters, but its exact specific determination is difficult to the writers becauseof the ill-preservation.
Occurrence and Lithology: A volcanic
sandstone layer of the Wanibuchi Formation.

References
Aoki, S. (1956): On the variation of Lima
(Acesta) goliath and its allied species,
with the description of a new species.
Trans. Proc. Palaeont. Soc. japan. N.S.,
no. 22, p. 185-190, text-figs. 1-3, pI. 29.
Hertlein, L. G. (1963): A new species ofgiant Lima from off southern California(Mollusca: Pelecypoda) .
Occas. Paps.
Calif. Acad. Scis., no. 40, p. 1-6, textfigs. 1-3.
New Eocene marine
Kamada, Y. (1973):
mollusca from the Takashima coal-field,
Nagasaki Prefecture, Kyushu. Sci. Rep.
Tohoku Univ., 2nd Ser., Spec. Vol., no.
6, p. 235-240, pI. 23.
Kuroda, T. (1932) in Kuroda: Catalogue ofshells from japan (in Japanese). Appendix of Venus, vol. 3, no. 4.
Merklin, R. L. (1954): Knowledge of the
Tertiary molluscan fauna in the northeastern Siberia (in Russian). Doklady,
Akad. Nauk. USSR, vol. 95, no. 2, p.
379-380, text-figs. 1-2.
Monden, S. (1960): A new locality of Lima
(Acesta) amaxensis (in Japanese). jour.
Geol. Soc. japan., vol. 66, no. 775, p.
280, text-fig. 1.
Noetling, F. (1901): Fauna of the Miocene
beds of Burma. Palaeontologia Indica,
N.S., vol. 3, pt. 3, p. 1-378, pIs. 1-25.
Okamoto, K. and Nakano, M. (1967): Some
Miocene limid fossils from the areaaround the Wanibuchi mine, Izumo
Province, Southwest Japan. Trans. Proc.
Palaeont. Soc. japan, N.S., no. 68, p.
185-192, pIs. 20-21.
Oyama, K. and Mizuno, A. (1958): On the
new forms of Paleogene mollusca fromJapan. Bull. Geol. Surv. japan, vol. 9,
no. 9, p. 1(589)-18(606), pIs. 1-4.

Explanation of Plate 58
Figs. la-b. Acesta (Plicacesta) watanabei Nakano et Okamoto sp. nov ................... p. 360
Para type (Silicon rubber cast from external mould), side (la) and laterally antero-dorsal(lb) views, xl.

NAKANO and OJ(AMOTO:

Acesta (Pl icacesta) 'Watanab wi

Plate 58

747_

Acesta (Plicacesta) watanabei from the Miocene

Ozaki, H. (1956): Two new fossils from the
Namigata Formation in Okayama Prefecture, western" Japan. Bull. Nat. Sci.
Mus., vol. 3, no. 1, p. 7-S, pI. 2.
Tottori Prefectural Government (1966):
Geological map of Tottori Prefecture(Scale 1: 100,000) and its explanatory
text (in Japanese). Tottori Prefecture.
Tottori Prefectural Museum (1976): Fossil
catalogue 2 (Bivalvia and gastropod
fossils from Tottori Group) (in Japanese).
Tottori Prefectural
21p., pIs. 1-4.
Museum.
Uozumi, S. (1962): Neogene molluscan faunasin Hokkaido (Pt. 1. Sequence and distribution of Neogene molluscan faunas).
Jour. Fac. Sci., Hokkaido Univ., Ser. IV,
vol. 11, no. 3, p. 507-544, text-figs. 1-11,
tabs. 1-3.
Vokes, H. E. (1963a): Studies on Tertiary
and Recent giant Limidae. Tulane Stud.
Geol., vol. 1, no. 2, p. 75-92, pIs. 1-2.
- - (1963b): Additions to a catalogue of thedescribed Recent and Tertiary species of363

Acesta and Plicacesta. Ibid., vol. 2, no.
1, p. IS-20.
Yamana, 1. (1962): On the topography andgeology of around Mt. Ooginosen, Tottori
Prefecture (in Japanese). Bull. Tottori
Pref. Mus., no. 1, p. 1-16, pIs. 1-3.
- - (1969): Fossils collected from Himejiarea, Koge-machi -Fossils occurred in
Tottori Prefecture (4) - (in Japanese).
Native Places and Sciences (Kyodo to
Kagaku) , vol. 15, no. 1, p. 5-S, figs. 1-6.
- - (1977): Molluscan assemblage from the
Miocene Tottori Group in the easternpart of Tottori Prefecture (in Japanese).
Bull. Tottori Pref. Mus., no. 14, p. 1-23,
pIs. 1-3.
Yokoyama, M. (1911): Some Tertiary fossils
from the Miike coal-field. Jour. Coli. Sci.
Univ. Tokyo, vol. 22, art. 20, p.I-16, pIs.
1-3.
- - (1925): Mollusca from the Tertiarybasin of Chichibu. Jour. Fac. Sci. Imp.
Univ. Tokyo, sec. 2, vol. 1, pt. 3, p. 111126, pIs. 14-15.

Hirata ilB3, Ibara ;it1J.l(, Iojima W::E£'"
Irino A!Ilf, Kaimon F7fJr~, Kawashimo fJiJr,
Miyajima '8£'" Namigata ~:Jfj, Nukakojima tllFf£'" Oyabe IJ'~$, Tadaura nlOO, Taisha:k:f!:, Tochimoto W*, Uchida F"lB3, Wanibuchi !~tJllf, Yashiro J\.~, Yokan ~fI, Yuyadani f~m:fl-

i19i'Yf B*,*,~ffi1EiJ' t? O)~fi Acesta (Plicacesta) watanabei ~;:. '?\" -C:~fE':*iJ' t? 0)

Acesta~ (Plicacesta !!P:~) 0)~1t:fi0)J.1l!5e.I¥J:5J'-;fp~j!lH&1...-C~#\,'t-.:,:c~iffi""', JlJ~.
~t~.if[O),*,~ilt Lima (Acesta) aff. amaxensis Yokoyama of Okamoto and Nakano,

1967 ~;:'%J 1..., ~:fj::g Acesta (Plicacesta) watanabei ~1Jj!P~ 1... t-.:.

Trans. Proc. Palaeont. Soc. Japan, N. S., No. 127, pp. 364-367, September 30, 1982

748. SEXUAL DIMORPHISM OF THE PALEOCOPID OSTRACODE
GENUS MANAWA FROM OKINAWA-JIMA*TOMOHIDE NOHARA and NORIKO NAKASONE
Department of Earth Sciences, College of Education, University of the
Ryukyus, Senbaru-1, Nishihara, Okinawa 903-01

Abstract. Three new localities of paleocopid ostracode genus Manawa arereported from Okinawa-jima. Examination of many individuals of Manawa konishii
indicates that the species is sexually dimorphic. The orientation of the genus Manawa
is discussed.

Introduction

The paleocopid ostracode genus Manawa
is at present known only from New
Zealand and Okinawa-jima of southern
Japan. The genus is very significant
because of its close resemblance to someof the Paleozoic Eurychilinas, as pointed
out by Hornibrook (1949).
The studies of the genus were originallycarried out by Hornibrook (1949, 1961).
In Japan, the occurrence of the speciesof this genus was reported first by Ishizaki (1973). Since then the studies werecarried out by Nohara (1976), and Nohara
and Miura (1977). In addition to thepreviously known occurrences of thefossil of the genus, new occurrencesfrom three other localities are reported
in this paper. The dimorphic features andthe carapace orienation of genus Manawa
will be discussed later.
Sampling localities

Fossil ostracodes of genus Manawa are
known at present from five localities of* Received November 5, 1981.

364

Pliocene Shinzato tuff and Pleistocene
Chinen sand. The specimens discussed
in this paper are mainly from Pleistocene
Chinen sand 500 m north of Asato,
Gushichan-son, Okinawa-jima (Loc. 1) and
Pliocene Shinzato tuff of the southern
cliffs of Miyagi-jima (Loc. 5).
The sampling localities are listed below,
and classic localities are marked with anasterisk:*Loc. I.-Chinen sand, 2 m above the roadcut,
500 m north of Asato, Gushichan-son,
Okinawa-jima, No. 1975122802-c (Lat. 26°
7'12"N, Long. 127°43'12"E), bluish grayfine silty sand, Pleistocene.
Loc. 2.-Chinen sand, the type locality, about
500 m east of Kudeken, Chinen-son, Okinawa-jima, No. 197571703 (Lat. 26°1O'N,
Long. 127°49'E), 3 m above National
Highway No. 329, silty sand, Pleistocene.
*Loc. 3.-Shinzato tuff, the type locality,
about 500m south-east of Shinzato, Sashikison, Okinawa-jima, No. 1976121501 (Lat.
26° 9'5"N, Long. 127° 46'7"E), bluish graysilty sand, Pliocene.
Loc. 4.-Shinzato tuff, the top of Miyagijima, Yonagusuku-son, Okinawa-jima, No.
198031505 (Lat. 26°21'18"N, Long. 127°
58'48"E), Pliocene.
Loc. 5.-Shinzato tuff, south side cliff of748. Paleocopid Ostracode genus Manawa
Miyagi-jirna, Yonagusuku-son, Okinawajirna, No. 198031506 (Lat. 26 D 21'12/1N, Long.
127 58'34/1E), bluish gray silty sand, Pliocene.
D

Discussion

It is well known that some living andfossil ostracodes are sexually dimorphic(Scott, 1961, Morkhoven, 1962, and Sarv,
1971). One of the authors (Nohara, 1969)
pointed out the possibility of sexual
dimorphism of paleocopid ostracode genus
Perprimitia (?) sp. Lately, the existenceof two forms of carapaces in Manawa
konishii was noted by Nohara and Miura(1977). The differences were noticeable in width in external view. The
differences are also noticeable in theinternal view of the carapace; one issmooth and the other is convex at thecentral muscle scar area. Such~a difference is neither enough to establish a new
species nor to treat as a continuous
variation, because it is very minor indimension but distinct enough to distinguish two types of carapaces. Other
features, such as muscle scar patterns
and surface ornamentations, are similar.
Figure 1 is a right valve of one formof Manawa konishii. In lateral view (Fig.
la), the surface reticulates and two
brackets are at the anterior and posteriorcardinal angles. In internal view (Fig.
Ib), a frill becomes slightly wider toward
the posterior. In dorsal view (Fig. lc),
the carapace is rugged and flat in thecentral and the posterior areas. Figure 2
is a left valve of the same form. In
lateral view (Fig. 2a), the dorsal margin
is straight and brackets are not present.
In internal view (Fig. 2b), sockets areobserved at anterior and posterior cardinalangles and the frill becomes wider toward
the posterior. In dorsal view (Fig. 2c),
the width becomes slightly greater toward
the posterior.

365

Figures 3 and 4 are right and left
valves of the other form. The carapace
appears to be the same as that of theformer form in surface ornamentation, inthe presence and absence of brackets atanterior and posterior cardinal angles inlateral view (Fig. 3a and 4a), and in theposteriorly wider frill in internal view(Fig. 3b and 4b). In dorsal view (Fig. 3c),
however, the carapace is distinctly
swollen toward the posterior.
In living ostracodes, the carapace ofthe female is quite often wider in theposterior part than that of the male
(Bonnema, 1930, Scott, 1961, and Morkhoven, 1962). The valves of Figures 1 and
2 are, therefore, quite likely to be a male
carapace, because there is no significant
swelling of the posterior part. On thecontrary, the valves of Figures 3 and 4
are probably a female carapace, since
there is a significant swelling of theposterior part. The swollen part indicatesthe manifestation of a sexual dimorphism,
as does the presence of the ovary andegg sacs in the posterior part of thefemale carapace.
The orientation of paleocopid ostracodegenus Manawa has been a problem.
Hornibrook (1949, figs. 1-8) oriented his
specimens as we did in this paper.
Scott (1961, figs. 2a-h), however, used thesame figures as Hornibrook (1949), but
gave his explanation of them in reverse
orientation. Their reasons for thus
orienting the specimens are not explainedin their papers as regards genus Manawa.
Our present study on sexual dimorphismof Manawa konishii suggests that a valve
with brackets is a right valve, and so avalve with sockets is a left valve. So,
we come to the conclusion that theorientation of genus Manawa by Hornibrook (1949) is tenable, while the orientation of genus Manawa by Scott (1961)
is untenable.

366

Tomohide NOHARA and Noriko NAKASONElc

4b748. Paleocopid Ostracode genus Manawa
References
Bonnema, J. H. (1930): Orientation of thecarapaces of Paleozoic Ostracoda. Jour.
Paleont. vol. 4, no. 2, p. 109-120.
Hornibrook, N, de B. (1949): A new familyof living Ostracoda with striking resemblances to some Paleozoic Beyrichiidae.
Royal Society of New Zealand, vol. 77, pt.
4, p. 469-471, pIs. 50, 51.
- - (1963): The New Zealand ostracodefamily Punciidae. Micropaleontology, vol.
9, no. 3, p. 318-320.
Ishizaki, K. (1973): Discovery of the family
Punciidae Ostracoda (Crustacea), from
Okinawa Island, Japan. Sci. Rep. Tohoku
Univ. 2nd ser (Geol.), Special Volume, no.
6 (Hatai Memorial Volume), p. 403-405, 1
fig., pIs. 47, 48.
Morkhoven, F. P. C. M. Van (1962): PostPaleozoic Ostracoda. Their morphology,
taxonomy, and economic use. vol. 1,
Elsevier Pub. CD. 204 pp.

I)

367

Nohara, T. (1969): Paleontological notes on
growth series and sexual dimorphism ofsome Mississippian ostracodes from Utah,
U. S. A. Bull. Sci. & Eng. Div. Univ. of
the Ryukyus. Math & Nat. Sci. no. 12.
- - (1976): Ostracoda of the genus ""Ianawa
from the Pleistocene Chinen Sand of the
Okinawa-jima.
Geol. Studies of the
Ryukyus Islands, vol. 1, p. 75-78.
- - and Miura, T. (1977): On the occurrences of Paleocopid ostracodes genus
Manawa from Okinawa-jima. Bull. Coll.
of Educ., Univ. of the Ryukyus, no. 21,
Pt. 2, p. 29-32 (in Japanese).
Sarv, L. T. (1971): Sexual dimorphism of
Early Paleozoic fossil Ostracoda. Vyalov,
O.S. (edit.), Israel Prog. Sci. Trans. Jerusalem. p. 11-23.
Scott, H.W. (1961): Orientation of ostracodeshells, in Treatise on Invertebrate Paleontology. Part Q, Arthropoda 3, Crustacea,
Ostracoda. Geol. Soc. Amer. Univ. of
Kansas Press. 442 pp.

rljt~~.iliHU~!H. lvlanawa ~O)ftl¥J 2 M: r*~.i£:O)~M!H. Manawa ~~t, ftt* 2 :nFJf J::Wl?n "n't.::.iJ~, 4"lillfTt.::.l:' 3 :nFJfO)fT.@J'I!!"k:iJUx.-e-llt 5 :nFJfO)~fTt!tfT![~JY(:'Ef:&Vc~fT

t!t:W~lijl:'EfiJ>I?.i£:l±l-rQ;: ciJ~biJ'-?t.::..

Manawa~~t,

Jlfj£t4MMJt~iJ~!N<t.(Q;: ciJ~biJ'-?

t.::.. ftt*Jlto) ~0)~Ej3 O):€(ft~:. '?\" -nt~jljLiJ~1:. L. -n ,t.::.iJ~, Jlfj£t4MMJt~O)~!N<O) iIDiJ' I?:€(ft"k~x.Q c

Scott (1961)

O):€(ft~t~~U~t.::.\".

![f!*iM*· {'l'*1iVJll:T

Figs. la-c. Lateral, internal, and dorsal views of the male right valve of Manawa konishii.
Sketched is Sample No. 1975122802-c, #14 from Loc. 1, x 100.
Figs. 2a-c. Lateral, internal, and dorsal views of the male left valve of Manawa konishii.
Sketched is Sample No. 198031506, #1 from Loc. 5, x 100.
Figs. 3a-c. Lateral, internal, and dorsal views of the female right valve of Manawa konishi.
Sketched is Sample No. 1975122802-c, #15 from Loc. 1, x 100.
Figs. 4a-c. Lateral, internal, and dorsal views of the female left valve of Manawa konishii.
Sketched is Sample No. 1975122802-c, #13 from Loc. 1, x 100.

Trans. Proc. Palaeont. Soc. Japan, N. S., No. 127, pp. 368-374, pI. 59, September 30, 1982

749.

ATRYPA (DEVONIAN BRACHIOPODA) FROM JAPAN*
PAUL COPPER
Department of Geology, Laurentian University, Sudbury, Canada

JUN-ICHI T AZA WA, KEI MORI
Institute of Geology and Paleontology, Tohoku University, Sendai 980

and
MAKOTO KATO
Department of Geology and Mineralogy, Hokkaido University, Sapporo 060

Abstract. The genus Atrypa is the only known atrypoid brachiopod represented
the Devonian strata of Japan, with Atrypina the sole atrypoid recorded fromfossiliferous Silurian rocks. The Fukuji Formation in central Honshu Island, ofprobable Siegenian·Emsian age, contains Atrypa (Atrypa) cf. A. Zorana Fuchs aswell as a more finely ribbed species, Atrypa (Atrypa) sp. The N3 member of the
Nakazato Formation in northeastern Honshu contains Atrypa (PZanatrypa) japonica
Sugiyama of middle to late Eifelian age. All the atrypoid taxa thus far known areof widespread distribution in the Devonian Old World province, particularly insiliciclastic-volcaniclastic Rhenish facies.
In

described by Sugiyama belongs neither
to the classical species Desatrypa desquamata Sowerby 1840, known from thelate Givetian of northwestern Europe (seeCopper 1965), nor to the Lower-Upper
Devonian genus Desquamatia Alekseeva
1960 to which many desquamata-likespecies have been attributed in the past.
Sugiyama (1942) and others, have thus
cited japonica as an indicator of Givetianage. This is shown here to be highly
unlikely as japonica belongs to the subgenus Atrypa (Planatrypa) Struve 1966,
which has never been recorded higher
than the late Eifelian. It is thereby
suggested that at least the Atrypa bed

Introduction

In 1942 Sugiyama described the first
discovery of Atrypa shells from theJapanese Islands, two somewhat poorly
preserved external moulds which werecited as Atrypa desquamata mut. japonica.
These specimens are in the collections of
the Institute of Geology and Paleontology,
Tohoku University and were re-examined
for this study. They come from what isprobably member N3 of the Nakazato
Formation in the Kitakami mountains ofnortheastern Honshu Island. The species* Received December 23, 1981.

368

749. Atrypa from Japanof the N3 member of the Nakazato Formation is no younger than late Eifelianage.
In 1956 Okubo described another species,
Atrypa pauciplicata from the Nakazato
Formation, in a locality close to, andprobably a horizon correlative with thesample of Sugiyama (1942). Okubo hada single brachial valve internal mould
available for study. Further material
available to us in the collections of
Tohoku and Hokkaido universities, andcomparison with Okubo's specimen
suggest very strongly that pauciplicata
is a junior synonym of japonica. Okubo(1956) also described an associated new
species of anoplothecid brachiopod,
Anoplotheca dorsosulcata which is referable to the Emsian-Eifelian genus
Coelospirina Havlicek 1956 by its strong
biconvexity and well-developed ribs on
both valves. From "Group II" in the
Kitakami region, Okubo (1950) had earlier
cited the occurrence of "Atrypa? sp." inpale greenish vitric tuffs. This material
has not been available for study, but thehorizon referred to is probably the underlying Ohno Formation of early Devonianage. No other brachiopods from this formation are presently known.
From the Hida massif in central
Honshu Island, Kamei (1952, 1955, 1961)
and Hamada (1961) first listed the occurrence of other Atrypa from Japan. These
were derived from various levels within
the Fukuji Formation and referred to as
Atrypa reticularis, A. tennesseensis or
Atrypa sp. Hamada (1961, fig. 22) first
figured a specimen of Atrypa from thisarea. In 1977 Ohno described the Fukuji
fauna in some detail confirming theSiegenian-Emsian age assigned to it byHamada (1961).
Brachiopods of the
Fukuji Formation are relatively wellpreserved calcareous shells showing little
deformation, like the shells from the369

Kitakami region. Ohno (1977) describedand figured two atrypoid species, forma
a and forma b, leaving them under open
nomenclature without assigning a genus
rank. Examination of to po typic material
in the Hokkaido University collections offorma b indicates a dorsi biconvex,
imbricately ribbed species with anadpressed ventral beak assignable toAtrypa (Atrypa). The stronger biconvexity
and greatly overlapping short growthlamellae of Atrypa (Kyrtatrypa) Struve
1966 are absent, the latter subgenus
ranging in known age from the Eifelian
to Frasnian.
Kamei (1952, 1955, 1961), who first
identified the Fukuji Formation, collected
Atrypa from the massive lower limestone
member (his unit 1), a crinoidal limestone(unit 7), a black, limy shale called the
Atrypa bed (unit 8) and an upper sandy
shale (unit 11). Ohno (1977), using a
different subdivision of the formation,cited no other occurrence than "bed B2",
also providing no other additional stratigraphic data for his Atrypa collections.
A recent revision of the Fukuji stratigraphy by Niikawa (1980) combines theunits employed by both Kamei and Ohno
into a four-fold division, units D1 to D4.
Unit D1 of Niikawa thus equates with
bed B of Ohno, unit D2 with beds C and
D (and D1-D2 with unit 1 of Kamei),
unit D3 includes beds E to I of Ohnoand units 2 to 6 of Kamei, and unit D4
includes beds J to N of Ohno and units
7 to 11 of Kamei.
The "forma a" atrypoid described by
Ohno in 1977 apparently came from thesame horizon as "forma b", i. e. unit Dl.
Tentatively, "forma a", which is rather
coarsely ribbed and has a flattened pedicle
valve can be referred to the SiegenianEmsian species Atrypa lorana Fuchs 1915,
known from the Bornicher Horizon ofOberstadtfeld, Germany (compare with

370

Paul COPPER et al.

Mauz, 1935, pI. 3, fig. 23). The typematerial of lorana is somewhat poorly
preserved, but somewhat coarser-ribbed
Atrypa appear to be fairly common in
the Emsian rocks of western Europe.
Therefore, on the basis of atrypoids, theFukuji Formation holds no forms diagnostic of Eifelian age, and could range inage from Siegenian through Emsian. A
Gedinnian age cannot be excluded at thepresent time because of our poor knowledge of Gedinnian atrypoids in the classic
Lower Devonian sections of Europe.
A third locality for Devonian Atrypa
was listed by Hamada (1959, p. 210) from
Fukui prefecture, south of the Hida
massif (Oisedani, Kamiise, Izumi village).
This outcrop of black limestones has a
Fukuji fauna and probably comes fromthe equivalents of the upper D4 member.
The specimens have not been examined.
Very recently Tachibana (1981) described
the first Silurian atrypoids from Japan,
Atrypina kitakamiensis n. sp. from the"Encrinurus bed" of the Kawauchi Seriesof probable Ludlovian age. This small
fauna from the Kitakami mountains ofnortheastern Honshu appears to be dominated by Salopina and Aegiria. No otheratrypoids are known in the Paleozoic
succession of Japan.

Eifelian age, e. g. by the presence of
Thysanopeltella (Septimopeltis) paucispinosa(Okubo 1951) and Phacops okanoi Sugiyama
1944, as re-described by Kobayashi and
Hamada (1977). Corals present include
the ubiquitous Calceola sp., Heliolites ex.
gr. porosus (Goldfuss), Pachyfavosites ex.
gr. polymorphus (Goldfuss) as listed by
Kato (1979, in Minato et al.).
Systematic descriptions

Order Atrypida Rzhonsnitskaya 1960
Family Atrypidae Gill 1871
Genus Atrypa Dalman 1828
Subgenus Atrypa (Planatrypa)
Struve 1966
Type species :-Atrypa (Planatrypa)
collega Struve 1966, p. 143-146, pI. 15, fig.

1, Giesdorf Horizon, Junkerberg Schichten,
middle Eifelian, Eifel region, Germany.
Diagnosis :-Medium to large Atrypa
shells with very fiat, even partly concave
pedicle valve, strongly convex brachialvalve, large sinus, strongly in curved or
adpressed beak, closely spaced imbricate
growth lamellae, very short frills or no
frills, moderately sized ribs.

The Nakazato Formation

This formation was first proposed in1937 by Yabe and Sugiyama as the
Nakazato Group, and subsequently given
formational status by Onuki (1956). It
consists of tuff and shale in the lower
part, shale and sandstone in the upper
part and totals some 530 m in thickness(Onuki, 1969).
The fauna of the Nakazato Formationis relatively sparse in comparison withthe older Fukuji Formation in central
Honshu. Trilobites tend to support a
Middle Devonian, most probably an

Atrypa (Planatrypa) japonica

Sugiyama 1942
PI. 59, Figs. 1a-4b.
1942 Atrypa desquamata mut. japonica Sugiyama, p. 127-128, figs. 1, la, lb.
1956 Atrypa pauciplicata Okubo, p. 39-40, pI.
3, fig. 5.

Type locality:-"Southwestern foot of
Takainari-yama, Hikoroiti-mura, Kesengun, Iwate-ken" (Sugiyama, 1942), Kitakami mountains, northeastern Honshu

749.

Atrypa from Japan

Island, Japan.
stratum :-Nakazato Formation,

Type

Member N3, in siliceous, tuffaceous
mudstones and siltstones.
No exact
horizon was given by Sugiyama in 1942.
Diagnosis: - Medium-sized (22-28 mmwide), slightly longer than wide, shieldshaped, convexoplane Atrypa with 4-6
ribs per 5 mm at the commissure, growthlamellae fairly regularly close-spaced at
1.0 to 1.5 mm, lacking frills. Beak weakly
protruding, ad pressed, hinge line weakly
concave, short, sinus moderate in height.
Materials :-All specimens are moulds
or casts preserved in tuffaceous mudstones or siltstones. There are two
syntypes in the Sugiyama collection, thelectotype being here chosen as the specimen IGPS 65468A figured by Sugiyama(1942, fig. 1), a partial external mould of

t
.

.
.
."
~

<

Hjgllchi~.

....1$'

"

o

"4

....

____~'"""

OMORI+39.06'
o,

, km

,

Fig. 1. Map showing the fossil locality
in the Hikoroichi district, Kitakami moun·tains, where hypo types of Atrypa (Plana.
trypa) japonica Sugiyama (IGPS 97685,
97686) were collected.

371

conjoined pedicle and brachial valve.
The second specimen, para lectotype IGPS
65468B (Sugiyama, 1942, figs. la, Ib), is adeformed partial mould of two conjoined
valves showing the umbonal region.
Additional material includes two external
pedicle valve moulds, hypo types IGPS
97685, 97686, which were collected by J.
Tazawa and K. Mori from shale float of
the upper Nakazato Formation, about 60
m below the top contact (= Phacops bedof Yabe and Sugiyama, 1937), midstream
in the Kuronbora valley, tributary of the
Omori valley (Fig. 1). Two hypotypes inthe Hokkaido University collections
include a mould, and facing cast, of asmall pedicle valve and a doubtful part
external mould of another specimen fromthe middle of the N3 member, Kuronbora
tributary, Omori valley (for sketch of thesection, see Minato et al., 1979, fig. 2b-3
for the horizon sampled).
The exact locality of Okubo's Atrypa
pauciplicata is unknown, except that it isroughly in the middle of the Higuchi
valley, about 1.7 km north of the Sugiyama outcrop.
Remarks :-The material is sufficiently
well preserved to identify generic andsubgeneric affinitie~, which lie with
Planatrypa. This is especially clear in the
new materials. In-terms of size and shapeas specific characters, Atrypa (Planatrypa)
japonica is close to A. (P.) squamifera
Schnur 1853, as illustrated by Schnur on
PI. 24, figs. 4a-b. Struve (1966) has
pointed out that the three syntypes in
the Schnur collection are not directly
referable to any Schnur figures, nor isthe precise locality or horizon known
since Schnur used the name squamifera
rather broadly for Eifel atrypids of the"reticularis" type. As a result, the present status of A. squamifera is uncertain,
only the Schnur illustration serving as
lectotype in lieu of a neotype designation

372Paul COPPER et al.

or revision of the species. Material similar
to the Schnur figure is most common in
the late Eifelian beds of the Eifel region.
It is quite possible that A. (P.) japonica is ajunior synonym of A. (P.) squamijera, thename being here retained for convenience,and not as an indication of its clear
identity or endemic nature.
Atrypa japonica has a larger size,
narrower shape and flatter pedicle valve
than Atrypa (Planatrypa) tirocinia Copper
1967 and is about two times wider than
Atrypa (Planatrypa) petasa Copper 1967,
with which it shares a common shapeand outline. The Sugiyama species isclearly smaller than Atrypa (Planatrypa)
collega Struve 1966, and, likes A. (P.) squamijera, spans the size gap between A. (P.)
collega and A. (P.) petasa, being most likesome of the specimens found in the Eilenberg Horizon of the Eifel region in Germany. It should here be noted that Atrypa(Planatrypa) tllola Copper 1967 is a juniorsynonym of A. (P.) collega Struve 1966.
Atrypa pauciplicata Okubo 1956, represented by a single internal brachialmould, is a probable synonym of A. (P.)
japonica because there are close similarities
in size and spacing of the ribs andgrowth lamellae, particularly with Sugiyama's paralectotype IGPS 65468B. Okubo
mentioned that "concentric lines andradial plications are more numerous in
Sugiyama's specimen", but this is clearly
not so. The Okubo specimen is definitelyreferable to Atrypa, and though thepedicle valve is not exposed; the brachialvalves are so similar that they are most
likely synonymous. We assume, therefore that the Atrypa-bearing bed of the
Higuchi valley is correlatable to the bed
in the Omori valley.

Acknowledgements

P. Copper wishes to thank the Natural
Science and Engineering Research Councilof Canada and Japan Society for the
Promotion of Science for co-sponsoring
field work and visits to the Institute ofGeology andPaleontology, Tohoku
University and the Department of Geology
and Mineralogy, Hokkaido University, in
1981.
We thank Mr. S. Otomo of the Instituteof Geology and Paleontology, Tohoku
University for photography.

References
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(1967): Atrypa (Planatrypa) , a neW
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1-12. (in Czech.)Kamei, T. (1952): The stratigraphy of the
Palaeozoic rocks of the Fukuji district,southern part of Hida mountainland. Jour.
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- - (1955): Classification of the Fukuji
Formation (Silurian) on the basis of
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- - (1961): Notes on Japanese Middle
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"Earth Science" (Chikyu
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naturf. Ces., Ht. 429, p. 1-94, pIs. 1-3.
Minato, M., Hunahashi, M., Watanabe, J. andKato, M. (ed.) (1979): Variscan geohistory of northern Japan: The Abean
Orogeny. 427 p., 144 pIs., Tokai Univ.
Press, Tokyo.
Niikawa, 1. (1980): Geology and biostratigraphy of the Fukuji district, Gifu prefecture, central Japan. Jour. CeoZ. Soc.
Japan, vol. 86, no. 1, p. 25-36. (inJapanese)Ohno, T. (1977): Lower Devonian brachiopods
from the Fukuji Formation, central
Japan. Mem. Fac. Sci., Kyoto Univ., Ser.
CeoZ. Miner., vol. 44, no. 1, p.79-126, pIs.
1-11.
Okubo, M. (1950): On the Gotlandian and
Devonian deposits of Hikoroichi, Kesendistrict, Iwate-prefecture. Jour. CeoZ. Soc.
Japan, vol. 56, no. 657, p. 345-350. (inJapanese)- - (1951): Trilobites from Japan. "Earth
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373

139, pI. 1. (in Japanese)- - (1956): Some Devonian brachiopods andtrilobites of the southern Kitakami
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22-29, 31-45.
Sowerby, J. de C. (1840): in Sedgwick, A.
and Murchison, R.1., On the physicalstructure of Devonshire and on the subdivision and geological relation of its
stratified deposits. Trans. Ceol. Soc.
Lond., vol. 5, no. 3, p. 633-703, pIs. 52-58.
Struve, W. (1966): Einige Atrypinae aus
dem Silurium und Devon. Senck. Zeth.,
Bd. 47, Ht. 2, p. 123-163, pIs. 15-16.
Sugiyama, T. (1942): New find of Atrypa
from Japan. Jour. CeoZ. Soc. Japan, vol.
49, no. 581, p. 73-75. (in Japanese)
Tachibana, K. (1981): Silurian brachiopods
from the Kitakami mountain land, northJapan. Ann. Rep., Fac. Educ., Iwate
Univ., vol. 40, no. 2, p. 29-54, pIs. 1-10.
Yabe, H. and Sugiyama, T. (1937): Preliminary report on the fossiliferous Gotlandianand Devonian deposits newly discoveredin the Kitakami mountain land. Proc.
Imp. Acad. Tokyo, vol. 13, no. 10, p. 417420.

Fukuji m:l.ill, Hida massif ~"JlJ:I.ill, Higuchizawa (Higuchi valley) :f§m j:J tJ{, Hikoroichi(Hikoroiti) B~m, Izumi ;fI:J7~' Kamiise l:{jt~, Kawauchi )II~, Kesen-gun ~fJlJiI1I, Kitakami mountains ~tl:JlJ:I.ill, Kuronborasawa (Kuronbora valley) !1 P /,,r. '7 tJ{, Nakazato 9=t m,
Ohno *!I!f, Oisedani *{jt~:f:t, Omorizawa (Omori velley) *~tJ{, Takainari-yama ~ftiU.ifJlJ

374

Paul COPPER et al.
13*.i![7";f- :/*c~JEM Atrypa : *~0)7";f- :/.*iJ,~Vt*¥Il11i·~.ht-: Atrypa O)?"tj, m~11l:t& :ffli:t&0) -rtl!W;f- :/.*:ffli:t&}!I.i![ 0) \:, O)t~ '"':)\"-(1";1:.

Atrypa (Atrypa) cf. A. lorana
Fuchs c Atrypa (Atrypa) sp. 0) 2 fiit~, "t tdU:I1l:t& 13 ~mO)*'ilB7";f- :/'**!!!}!IJ:'ilBN 3 'ilB}!I.i![0) \:, o)f'i. Atrypa (Planatrypa) japonica Sugiyama 1 fiit~"t c IJb ~.h7.> • .:..h~fi.\"-r.h\:, r1 -;10)'71 :/mt~~.i![i""7.> Atrypa t~JlI~tJ:fii""C'~7.>c~;t~.h7.>.
*mfBX""C'fi.*!!!}!I.i![o)iJ''"':)-C~11l (1942) t~J: IJ Atrypa desquamata mut. japonicac~tI(;~.ht-:fii~, ~11l0)~* (~~j\;;~*) c~t..:t~tlE~ 1...-t-:~*~ \:, c t~ Atrypa(Planatrypa) japonica c 1.. - -c~~tI(; 1.. - t..:. *fiili. 71 7 :r. Iv:t&f!i1GO) 71 7 :r. Iv~J:'ilBt~.i![i""7.> Atrypa (Planatrypa) squamifera Schnur O)~~ '/ / ::. A ""C'~ 7.> iiJ~M:iJt~\, '. Atrypa(Planatrypa) Ii.';'" - 7'-7 :/ j;.Jl*t~Ii.%l ~.h -c\" tJ:""~: c iJ' ~, *!!!}!IJ:'ilB0)~~1i.';"'7'-7 :/ c 1i.tJ: ~-r, 71 7:r. V 7 :/J:jJ;MtJ:\" 1...-~;M""C'~7.> c ~;t ~.h7.>.

P. :J .., J~-•

EBiR~-. ~~. bu~~

Explanation of Plate 59
Atrypa (Planatrypa) japonica Sugiyama 1942
Figs. la, lb. Hypotype IGPS 97685, from shale float of the upper Nakazato Formation, about
60 m below the top contact, middle of Kuronborasawa stream, tributary of Omorizawa,
Hikoroichi district, Kitakami mountains, NE Japan. Fig. 1a is the latex cast of a pedicle
valve; Fig. 1b is the original external mould of the same valve.
Figs. 2a, 2b. Hypotype IGPS 97686, from the same locality as Figs. la, lb. Fig. 2a is the latex~!iS~ of a PE!dicte valve; Fig. 2b represents the external mould.
Fig. 3. Latex cast of a pedicle valve. Lectotype IGPS 65468A, figured by Sugiyama, 1942, fig.
l,~one of two syntypes in the Sugiyama collection, Tohoku University.
Figs. 4a, 4b. Latex cast of paralectotype IGPS 65468B, figured by Sugiyama, 1942, figs. la, lb.
Fig. 4a is the ventral view; Fig. 4b is the posterior view.
All figures are twice natural size.

COPPER et al.:Atrypa from Japan

Plate 592a4bTrans. Proc. Palaeont. Soc. Japan, N. S., No. 127, pp. 375-385, pI. 60, September 30, 1982

750.

ON SOME LOWER TRIASSIC AMMONITES FROM THE OSAW A
FORMATION AT ASADANUKI, TOWA-CHO, TOME-GUN,MIYAGI PREFECTURE, NORTHEAST JAPANYUJI BANDO

Department of Geology, Faculty of Education, Kagawa University, Takamatsu, 760

and
MASA YUKI EHIRO
Department of Earth Sciences, College of General Education,
Tohoku University, Sendai, 980

Abstract. Two Lower Triassic ammonites, Procarnites kokeni (Arthaber) andEosturia towaensis Bando and Ehiro gen. et sp. nov., from the Osawa Formation in
the southern part of the Kitakami Massif are described. These ammonites indicate
the Latest Scythian or Latest Spathian age and belong to the Subcolumbites perrinismithi Zone biostratigraphically. Morphological and septal features suggest that the
new genus Eosturia may be intermediate between the Lower Triassic Procarnites
and the Middle Triassic Sturia.

and Lower Triassic formations of theworld.
Lower Triassic ammonites from theOsawa Formation of the Kitakami Massif
were described by Bando (1964, 1966,1970) and Bando and Shimoyama (1974)
as the Subcolumbites faunas, but up to
now Procarnites has not been discoveredin the Kitakami Massif.
Historically, the Osawa Formation has
been studied by many authors. For
example, Mabuti (1932) discovered specimens of Lower Triassic pelecypods suchas "Pecten" (Eumorphotis) ussuricus(Bittner), "Pecten" sichoticus (Bittner),"Pecten" d. discites (Schlotheim), Pecten
alberti virgalensis (Wittenburg) at Tatenear Isatomae, but since then no otherfossils have been discovered in the Lower
Triassic.
Subsequently, Shiida (1939)

Introduction

Two specimens of Lower Triassic
ammonites, Procarnites kokeni (Arthaber)and Eosturia towaensis gen. et sp. nov.
were discovered in the Osawa Formation
at Asadanuki, Towa-cho, Tome-gun,
Miyagi Prefecture, in the southern partof the Kitakami Massif. These ammonites
occur in the uppermost part of the Osawa
Formation and belong to the latest
Scythian, which corresponds to theProhungaritan ammonite stage (Spath,
1930, 1934) or latest Spathian age (Tozer,1965). The ammonites are also very
important in establishing internationalcorrelation between the Osawa Formation
Received February 12, 1982; read on January
23, 1981, at the Annual Meeting of 1981 at
Sendai.

375

376

Yuji BANDO and Masayuki EHIRO

surveyed the area in which the present
specimens occur and subdivided theTriassic beds into HI to H4 members inascending order and included them in the
Hiraiso Formation. Later Inai (1939),
Ichikawa (1948, 1951), Mito (1957), Onuki
and Bando (1959a) and Bando (1958, MS)
contributed to the stratigraphy and subdivision of the Osawa Formation. Ichikawa (1948, 1951) proposed the name
Osawa Formation and referred it to his
Tatean age of the Lower Triassic chronological subdivision of Japan.
In 1964, Bando described Subcolumbites
cf. perrinismithi Arthaber based on thecollection of Prof. Onuki from the Osawa
Formation at Tate near Isatomae, andsubsequently also described other Lower
Triassic ammonoids, e. g. Flemingites sp.,
EUflemingites sp., Meekoceras spp., Xenoceltites ? sp. and Danubites sp., from theOsawa Formation on the coast at Hiraiso,
Motoyoshi-cho, Motoyoshi-gun, Miyagi
Prefecture. In addition, Bando (1970)
described the Leiophyllites fauna, which
consists of L. cf. pitmnaha (Diener), L. aff.
pradiumna (Diener), L. sp. and Danubites
aff. ambika Diener, from the Osawa Formation at Konori near Onagawa-cho,Ojika-gun, Miyagi Prefecture, on the basisof the collection of Prof. Onuki. Bandoand Shimoyama (1974) also describedfurther members of the Subcolumbites
fauna i. e. Preflolianites aff. sulioticus(Arthaber), Columbites parisianus Hyattand Smith, C. sp., Eophyllites cf. dieneri(Arthaber), Leiophyllites sp., Stacheites sp.,
Nordophiceras sp., Arnautoceltites sp.,
Prenkites cf. timorensis Spath, P. sp., Prohungarites? sp., Dalmatites sp., Subcolumbites perrinismithi (Arthaber), S. sp.,Isculites aff. originis (Arthaber), from theOsawa Formation at the type locality,
Hiraiso, Motoyoshi-cho; Motoyoshi-gun,
Miyagi Prefecture. The Subcolumbites
fauna is found about 30 m above the topof the subjacent Hiraiso Formation.
On March in 1980, the junior author(M. E.) collected an ammonite, Procarnites,from the uppermost part of the Osawa
Formation at 2 km southest of Asadanuki,
Towa-cho. In addition, we again visitedthe locality of Asadanuki on January in1981 in association with Prof. M. Murata
of Kumamoto University and at that time
we collected an interesting ammonite,
Eosturia, described in this paper.
The Osawa Formation, which has
yielded the present specimen is thicker
than the Hiraiso Formation, and the mainpart of the formation may comprise theP r oh ungari tan -Co 1u m bit an ammonite
stages of Spath (1930, 1934), as alreadymentioned by Bando and Shimoyama (1974).

Stratigraphical Note on the Lower
Triassic Formations in theSouthern Kitakami
Massif
The Lower Triassic of the southernpart of the Kitakami Massif consists ofthe two formations, the Hiraiso Formation
below and the Osawa Formation above.
These formations are distributed along
the eastern and western margins of thesouthern Kitakami Massif, and lie on thesubjacent Upper Permian Toyoma Formation and its equivalents (Fig. 1). At
the Hiraiso coast, the type area of theLower Triassic formations, the Hiraiso
Formation, about 160 m thick, is composedof basal conglomerate which unconformably overlies black shale of the Toyoma
Formation, coarse sandstone in the lower
part and a banded alternation of sandstone and shale in the upper part. The
latter grades upwards into a laminatedalternation of shale and sandstone ofsuperjacent Osawa Formation. From thetype locality of the Hiraiso Formation,

750. Lower Triassic ammonites from Kitakami

~

m
r::.D

•

~

Granitic rocks
Up. Triassic

Mid. Triassic

Low. Triassic~§ Low.

Up. Perman

MId,

Permian

0_==--===-1..
0 km

Fig. 1.

Geologic map of the southern part of the Kitakami Massif. (Geologic data
based on various sources and map compiled by M. Ehiro)

377

Yuji BANDO and Masayuki EHIRO

378

present fossil locality, Lower Triassic
formations are widely distributed in a
synclinal structure, whose axis plunges
gently to the south (Fig. 2). The lithologic features and thickness of the formations differ somewhat from those of
the type locality on the Hiraiso coast.
The Hiraiso Formation in the Mizusakaitoge area, 200-250 m in thickness, contains
thin beds of reddish or greenish tuff in
the lower part. The lithologic characterof tuffs in the basal part - of the Hiraiso

the Early Scythian ammonoid "GlyptoPhiceras" d. gracile has been described byBando (1970). The Osawa Formationconsists of alternating - laminated shaleand sandstone in the lower part and darkgray shale in the upper part, and isestimated to be 300 m thick. The formation is covered by thick sandstone of
the Middle Triassic Fukkoshi Formation.
The Osawa Formation yields abundant
Scythian ammonoids as already mentioned.
In the Mizusakai-toge area, including the1..i1km:t:'=::c::JI_ _

Ocr

~lJ

KUROMORI====~.::::<--. 'p:;:::====~:

t=======4°==:;.:::~0~q : :::~32===~'....
...........

==~ 49 ••. :~.
-",,-,''''-,;::===~;:-.

. ::: ::13"::::: 38~\;: :~.;;:;;:::==~i.:f===~2:::::'Z:....;.:.~::::::.;-..,.
.. - -:'.,1

....

.1==
~~;,c::::::

3 4 - - 40-#55'"......... .

':::::: 56'~::0---"f~=<'~~2..........•..

39':~:::::::.~==t==_•• ,.' •••••••;::::.- _ ----\----=:4"-:.8.............

:I==:t.'r.. ::''---""'--·~----24............... J" ' " f---------,--D!:il-~:::.;:..
.. .•..........
:~ ..... .

-I--=L ~~~g:~~~~5~~::::j.~GS-~ ~ ~ ~.~~----,138~~~~~60"\' ~:""::.::1-:: :'::::'y :: - ~t 75:

J--_ _ _ _ _3 ~_"~UPPER PERMIAN[J]
Fig. 2.

TOYOmaForm.

__________~)_ _ _ _ _ _ _ _~180~~

LOWER TRIASSIC~Osawa~Form.

MIDDLE TRIASSIC

f===l Isatomae
t:==j

Form.

*'

fossil locality

1::::::1
17'.. . . . . Fukkoshi
Form.
L.L..-l Porphyrite

Geologic map of the ammonite locality at Asadanuki near Towa·cho, Tome·gun,
Miyagi Prefecture. Geologic survey carried out by M. Ehiro.

750.

Lowe?" Triassic ammonites from Kitakami

Formation was studied by Onuki andBando (1958) and regarded as productsof the basic volcan ic activity in theearliest Lower Triassic. The Osawa
Formation contains thick beds of sandstone in the middle part, and the total
thickness attains 400 m. The present
ammonites were collected from the sha lesin the uppermost part of the Osawa
Formation, about 20 m below the base of
the Fukkoshi Formation (Fig. 3) in theupper reaches of Na meshi-zawa, southeast of Asadanuki, Towa-cho, Miyagi
Prefecture.
From the stratigraphic
evidence, although no additional ammonoids

379

were found at the locality, the horizonof the present specimens especiallycorresponds to the Arnautoceltites zoneof the type locality.
Description of Ammonites
Class Cephalopoda Cuvier, 1797
Subclass Ammonoidea Zittel, 1884
Order Ceratitida Hyatt, 1884
Superfamily Noritaceae
Karpinsky, 1889
Family Proptychitidae
Waagen, 1895
Genus Procranit es Arthaber, 1911

u

lil
(j)

::sa:

15ATOMAE

Type species:

FORM.

I-

Remarlzs : Procarnites predominates in
the uppermost Scythi an, i. e. the Prohungaritan (Spath, 1930, 1934) or the latest
Spathian (Tozer, 1965), and is generally
associates w ith the Subcolumbites fauna
which consists of Subcolumbit es, Columbit es,

lJ.J
..J

0
0

2:

FUKK05H I
FORM.

u

lil
(j)

:::a:

05AWA
FO RM.

I-

a:
lJ.J
:;;
0

....J

2'
a:

ParajJopanoceras Iwlzeni

Arthaber, 1908

HI RAI50
FORM.
TOYaMAg:

FORM .

•.•....
......... ':onglomer ot e 1:':1
sandstone.. ~1:::::1

alt . sst. & sh .

§l am . alt. sh. & sst.

-xammoniteFig . 3. Geo lo gica l columna r sect ion of
the Lo wer an d Middle Triassic a t Asadanuki , showi ng the horizon of Procarnites
and Eo st uria at the top of the Osawa Formation.

Prohungarites, NordojJhiceras, Isculites,
Prenhites, Leiophyllites, etc.
From the phylogenetic point of view,
the present genus may be ancestral to
Sturia (Ptychitidae) and an intermedi ate
form may be represented by Eosturia
gen. nov. descr ibed below. Procarnites
and Eosturia are both assoc iated in thesame horizon of the Osawa Formation in
the Kitakami Massif .
Occurrence and geological horizon:
Prohungaritan or Latest Spathian of theLower Triassic.
T imor, Salt Range(Pakistan), Afghanistan, Chios (Greece),
Albania, South China, Japan, Siberia andBritish Co lumbia.

380

Yuji BANDO and Masayuki EHIRO
Table 1. Measurement in mm [Procarnites kokeniJ.

GLKU-Os-80004

D

H

W

U

HID

W/H

U/D

57.0

32.9

11. O?

6.0

0.57

0.33?

0.1

D: Diameter of shell, H: Height of whorl, W: Width of whorl, U: Diameter of umbilicus.

Procarnites kokeni (Arthaber, 1908)
PI. 60, Figs. 1a-b; Text-fig. 4A
1W8. Parapopanoceras kokeni Arthaber, p.
259, pI. 11 (1), figs. 1a-c, 2a-b.
1911. Procarnites kokeni, Arthaber, p. 215,
pI. 17(1), figs. 16, 17, pI. 18(2), figs. 15.
1915. Procarnites kokeni, Diener, p. 228.
1917. Procarnites kokeni, Diener, p. 167.
1928. Procarnites kokeni, C. Renz, p. 155.
1947. Procarnites kokeni, C. Renz and O. Renz,
p. 61.
1948. Procarnites kokeni, C. Renz and O. Renz,
p. 81, pI. 8, figs. 5, 6-6a, 8-8a; pI. 9,
figs. 2-2a.
1966. Procarnites kokeni, Kummel, p. 390, pI.
2, figs. 10-13.
1968. Procarnites kokeni, Kummel, p. 391, pI.
11, figs. 1-4; pI. 12, figs. 1-2; pI. 13,
figs. 1-8.
1978. Procarnites kokeni, Wang, p. 167, pI.
11, figs. 15-19.
1968. Procarnites aff. kokeni, Bando, p. 101,
pI. 6, figs. 3a-b.
1934. Procarnites acutus Spath, p. 183, pI. 5,
figs. 4a-b.

Material: A single specimen was
examined.
Description: Shell involute, discoidal,
laterally compressed, with smooth shellsurface, narrowly rounded venter andsmall funnel-shaped umbilicus as inptychitids.
Outer whorl completely
embraces inner whorls. Suture consistsof entirely rounded saddles and denticulated lobes, but median siphonal saddle
not observed; first lateral saddle largest
and others gradually becomes smaller
toward umbilical margin; first laterallobe highly denticulated and deeper thanother lateral lobes.
Remarks: This specimen is not wellpreserved, but preservation of the shellsurface, umbilicus and sutures is goodand quite adequate for specific identification. The suture especially is wellable to be identified with that of Procarnites kokeni (Arthaber), as illustrated
in Fig. 4. Unfortunately, the type specimen described by Arthaber (1908) is arather small and immature one with more
simple sutures than those of specimens
described by Renz and Renz (1948) from
Chios Island in Greece. As already discussed by Kummel (1969, p. 391-396) the
large number of P. kokeni from Chios,
which have been described by Renz andRenz, show much variability in the whorl
section, from a broadly rounded venter
to a rather acute venter like that of
Spath's holotype of P. acutus (Spath, 1934,
p. 183, pI. 5, figs. 4a-b) from Kcira in
Albania. Thus, Kummel (1969) included
P. acutus in P. kokeni on the basis of theabove mentioned variability of the venterof that species. The present writers
agree with the opinion of Kummel inthis point.
P. kokeni is a member of the Tethyanammonite fauna and has been recorded
from Albania (Arthaber, 1911), Chios(Renz and Renz, 1948), Mangyshlak
Peninsula of the Caspian region (Kiparisova, 1947, as P. andrusovi Bakarunas,
1936), Afghanistan (Kummel, 1968), Salt
Range in Pakistan (Kummel, 1966), Timor(Spath, 1934; Bando, 1968, in Nakazawa
and Bando) and recently from the Mount
Jolmo Lungma region in Tibetan Hima-750. Lower Triassic ammonites j?'orn Kitakami
I

381!?J1M (

r
I

I

I

,

I

B

c

Fig. 4. Suture lines of Procarnites kokeni (Arthaber). A: present specimen, at a diameterof 34 mm, Osawa Formation; 8: lectotype by Arthaber (1908, pI. 11 (1), fig. 1c) at a diameterof 33mm (see also Kummel,1969, p.392, fig. 12(A)). Albania. C: plesiotype by Arthaber(1911, pI. 18(2), fig. 2c) (see also Kummel, 1969, p.392, fig. 12(C) at a diameter of about 80 mm.
Albania. D: lectotype of Procarnites skanderbegis Arthaber (1911, pI. 18(2), fig. 7c) at a diameter of 55 mm; see also Spath (1934, p. 180, fig. d and Kummel (1969, p. 392, fig. 12(F)).
Columbitan. Albania.

layas (Wang and He, 1976, as P. d.
kokeni).
In south China, Zhao (1959)
described P. oxynostus Chao from theLower Triassic of Kwangsi, but Kummel(1969, p. 391) included the Chinese
species in P. kokeni (Arthaber) becauseof their close similarity in shell form.
Biostratigraphically the present species
occurs in the latest Scythian age, coexisting with Subcolumbites, Nordophiceras,
Arctomeekoceras, Prejlorianites, Prohungarites, Proptychites and Isculites. In theSalt Range, the horizon of P. kokeni isabout 30 m below the base of the Middle
Triassic Tredian Formation at Nammal
Gorge (Pakistan-Japanese Research Group,1981).
In the Kitakami Massif, northeast
Japan, the Subcolumbites fauna including
Procarnites occurs probably in the same
beds as Utatsusaurus hataii Shikama,
Kamei and Murata, a kind of Ichthyosaurid,
and a little below the bed with Leiophyllites. In Eastern Timor, Procarnites

kokeni was described by Bando (Nakazawa
and Bando 1968, p. 101) from the Uppermost Scythian beds 7 km west of
Manatuto based on the collection ofProfessor K. Nakazawa in 1961. Procarnites from Eastern Timor is associated with
Leiophyllites timorensis Bando, Pseudosageceras d. multilobatum Noetling, Tropigastrites aff. lahontanus Smith, Meekoceras nakazawai Bando etc. (Nakazawa
and Bando, 1968, p. 91).
Occurrence and geological horizon: Dark
gray shale of the uppermost part of theOsawa Formation 2 km southeast of Asadanuki, near Mizusakai-toge, Towa-cho,Tome-gun, Miyagi Prefecture, southernpart of the Kitakami Massif. Subcolumbites perrinismithi Zone of the latest
Scythian. Reg. No. GLKU-Os-80004. Coil.
M. Ehiro, 1980.

Superfamily Ptychitaceae
Mojsisovics, 1882

382

Yuji BANDO and Masayuki EHIROFamily Ptychitidae Mojsisovics, 1882
Genus Eosturia Bando ~nd
Ehiro, gen. nov.
Type species: Eosturia towaensis Bandoand Ehiro, 1982.
Diagnosis: Shell involute, discoidal,
highly laterally compressed, with closed
umbilicus, narrowly rounded venter, andslightly convex sides. Surface ornamented :,with spiral striae on flanks and by weakradial folds ventrally. Suture ammonitic,
saddles with simple phylloid terminations
and lobes ammonitic.
Remarks,' The present new genus isancestral to Sturia Mojsisovics (1882)
which is a characteristic of the Middle
Triassic, especially Anisian age, because
the shell ornamentation of spiral striae inthe present genus shows the features of
Sturia, but there are radial folds on theventral margin of the shell and moreoverthe suture is simpler than that of
Psilosturia Diener (1916) or Stu ria in theform of the lateral saddles. Psilosturia
has a wider umbilicus and more complicated sutures than either Eosturia or
Sturia. The diameter of the umbilicusof Psilosturia is about 1/7 of the total
shell diameter.
The genus Eosturia is considered to be
an intermediate group between the
Procarnites and Sturia because of thefeatures of shell ornamentation and thesuture. Biostratigraphically, the present
genus occurs in the Subcolumbites Zone
in association with Procarnites kokeni
described above. In the Kitakami Massif
species of Sturia, e. g. S. japonica Diener
and S. d. sansovinii Mojsisovics, were
described from the Isatomae Formationof the Middle Triassic (Diener, 1915 ;Onuki and Bando, 1959b), but no speciesof Struia have yet been found in theLower Triassic Osawa Formation. Pre-

vioilsly, species of Stu ria were thought
to have been restricted to Middle Triassic
strata of the Tethys region of the Alpsand Himalayas, but no species of Stu ria
not even an ancestral form has yet been
discovered in the Lower Triassic of that
region.
Jacobshagen and Tietze (1974) described
an interesting species, "Sturia" n. sp.,from the Subcolumbites beds of the Greek
Island of Chios and they suggested thatsome species of Columbites, Subcolumbites,
and other Spathian ammonites are associated there with "Anisian" elements.
That species of "Sturia" might fall inthe scope of variation of Eosturia in shellform, sculpture and sutural pattern, but
it is difficult to compare whorl sections
because no illustration was provided by
the authors.
Occurrence and geological horizon:
Prohungaritan or late Spathian of theLower Triassic. Subcolumbites perrinismithi Zone.
Eosturia towaensis Bando andEhiro, n. sp.
PI. 60, Figs. 2a-b; Text-fig. 5

Material:
A single specimen was
examined.
Diagnosis:
Shell involute, discoidal
highly laterally compressed, with closed
umbilicus, narrowly rounded venter, andslightly convex sides.
Shell surface
ornamented with numerous spiral striae
and indistinct ventral radial folds. Sutureammonitic, consisting of simple phylloid
lateral saddles and denticulated ammonitic
lateral lobes.
Description: Shell completely involute,
discoidal, laterally compressed, withclosed umbilicus, narrowly rounded venterand slightly convex sides. Inner whorl
about half height of outer whorl.

750. Lower Triassic ammonites from Kitakami

383)

Fig. 5. Suture line of Eosturia towaensis Bando and Ehiro, gen. et sp. nov. GLKU-OS-81001,
H=28.4 mm Osawa Formation at Nameshi·zawa, Asadanuki, Towa·cho, Tome·gun, Miyagi Prefecture.

Maximum width at half height of thewhorl. Venter very narrow and rounded.
Shell surface ornamented with numerous
spiral striae as in Sturia and by indistinct fine radial folds which are observedon the ventral sides of shell, extending
from 2/3 height to the venter. Sutureammonitic, consisting of phylloid andterminated lateral saddles and of denticulated ptychitid lateral lobes, but theventral lobe is unfortunately unknown(See Fig. 5).
Remarks: The general characters of
the shell of the present species resemble
those of the species of Sturia, especiallyS. japonica and S. sansovinii, but thesimple suture of the new species differsfrom that of Sturia. Moreover, the faintradial folds, which are projected forwards
near the venter, on the ventral sides ofthe shell are not known in any speciesof Sturia. Judging from its suture thepresent species may be intermediate
between Procarnites and Sturia.
In
general, the suture of Stu ria is more
complicated than that of Procarnites andabout as complex as those of Ptychites
and Gymnites of the Middle Triassic.
The present new species is associatedwith Procarnites kokeni (Arthaber) in theOsawa Formation and the writers cannot
find any comparable Lower Triassic
species.
Occurrence and geological horizon:
Dark gray shale of the uppermost partof the Osawa Formation 2 km southeastof Asadanuki, near Mizusakai-Toge, Towacho, Tome-gun,
Miyagi Prefecture,southern part of the Kitakami Massif.
Subcolumbites Perrinismithi Zone of theLower Triassic. Reg. no. GLKU-Os81001. ColI. Y. Bando and M. Ehiro, 1981.
Acknowledgem nts

The authors thank Prof. Dr. M. Murata,
Faculty of Science, Kumamoto University,
for his kind assistance and encouragementin the course of this study. Thanks are
due to Dr. J. A. Grant-Mackie of the
University of Auckland, New Zealand,
for reading the manuscript.

Table 2.

Measurements in mm [Eosturia towaensis n. sp.]

D

H

W

U

HID

W/H

U/D

49.4(34.2)

8.0?

0.5

0.60

0.16

0.01

GLKU-Os 82.0(56.7)-81001

384

Yuji BANDO and Masayuki EHIRO
References

Arthaber, G. V. (1908): tiber die Entdeckung
von Untertrias in Albanien und ihre
faunistische Bewertung. Mitt. Geol. Ges.
Wien, Bd. 1, S. 245-289.
- - (1911): Die Trias von Albanien. Beitr.
Paliiont. Geol. Ost.-Ung., Bd. 24, S. 169277.
Bando, Y. (1958): Study on the Triassic
stratigraphy in the Kitakami Massif.
(M. Sc. degree graduation thesis, Tohoku
Univ., MS, in Japanese).
- - (1964): The Triassic stratigraphy andammonite fauna of Japan. Sci. Rep.,
Tohoku Univ., 2nd Ser. (Geol.), vol. 36,
no. 1, p. 1-137.
- - (1966): A note on the Triassic ammonoids of Japan. Mem. Fac. Lib. Arts &Educ., Kagawa Univ., Pt. II, no. 138, p.
1-19.
- - (1970): Lower Triassic ammonoids
from the Kitakami Massif. Trans. Proc.
Palaeont. Soc. Japan, N. S., no. 79, p. 337354.
- - and S. Shimoyama (1974): Late Scythianammonoids from the Kitakami Massif.
ibid., N. S., no. 94, p. 293-312.
Diener, C. (1915): Fossilium Catalogus. 1.
Animalia. Pt. 8, Cephalopoda Triadica.
Berlin, 369 pp.
- - (1916): Japanischen Triasfaunen. Denkschr. K. K. Akad. d. Wiss. Wien, Bd. 92,
S. 1-30.
- - (1917): tiber Ammoniten mit Adventiloben. Denkschr. K. K. Akad. d. Wiss.
Wien, Bd. 92, S. 1-30, Bd. 93. S. 139-199.
Ichikawa, K. (1948): On the Lower andMiddle Triassic stratigraphy of Tsuya
and Isatomae areas in southern part of theKitakami Massif. Jour. Geol. Soc. Japan,
vol. 53, p. 79-80 (in Japanese).
- - (1951):
Triassic formations in thesouthern part of the Kitakami Massif. (inthe Triassic stratigraphy of Japan).
Repts. Spec. No., Geol. Surv. Japan, p.
7-26 (in Japanese).
Inai, Y. (1939): Geology of Shizugawa andits environs in Miyagi Prefecture. Jour.
Geol. Soc. Japan, vol. 46, p. 231-242 (inJapanese).
Jacobshagen, V. and K. W. Tietze (1974):
Biostratigraphische Probleme in Skyth/Anis-Grenzbereich auf der Insel Chios(Agiiis). in "Die Stratigraphie der alpinmediterran Trias"(1973).
Schrift,
Erdwiss. Komm. Osterr. Akad. Wiss., Bd.
2, Wien, S. 115-123.
Kiparisova, L. D. (1947): Atlas of the guide
forms of fossil faunas of the USSR. Pt. 7,
Triassic system. All Union Sci. Res.
Geol. Inst. (VSEGEI) , 251p. (in Russian).
Kummel, B. (1966): The Lower Triassic
formations of the Salt Range and TransIndus Range, West Pakistan. Bull. Mus.
Comp. Zool., vol. 134, no. 10, p. 361-429.
- - (1968): Additional Scythian ammonoids
from Afghanistan. ibid. vol. 136, no. 13,
p. 485-509.
- - (1969): Ammonoids of the Late Scythian(Lower Triassic). ibid. vol. 137, no. 3,
p. 311-702.
Mabuti, S. (1932):
Stratigraphy of the
Tatsukane Mass in southern Kitakami
Massif (Graduation thesis, Tohoku Univ.,MS, in Japanese).
Mito, A. (1957): Geology of the Mizusakai

Explanation of Plate 60
Figs. la-b. Procarnites kokeni (Arthaber) ............................................ Page 380
GLKU-Os-80004, 1a: lateral view, x 1.4; 1b: cross section of last whorl, xL
Figs. 2a-b. Eosturia towaensis Bando and Ehiro ...................................... Page 382
GLKU-Os-81001, 2a: lateral view, xLI; 2b: cross section of last whorl, xL
Both specimens illustrated here were collected from the uppermost part of the Osawa Formation at 2 km southeast of Asadanuki, near Mizusakai-toge, Towa-cho, Miyagi Prefecture,southern part of the Kitakami Massif. Lower Triassic.

BANDO and E HI RO:

Lower Triassic ammonoids

2b

Plate 60

750. Lower Triassic ammonites from Kitakami
Pass area, Miyagi Prefecture, in thesouthern Kitakami Massif (Graduation
thesis, Tohoku Univ., MS, in Japanese).
Nakazawa, K. and Y. Bando (1968): Lower
and Middle Triassic ammonites from
Portuguese Timor (Palaeontological Studyof Portguese Timor, 4). Mem. Fac. Sci.,
Kyoto Univ., Ser. Ceol. & Min., vol. 34,
no. 2, p. 83-114.
Onuki, Y. and Y. Bando (1958): On the tuff
of Lower Triassic formations in the
Kitakami Massif. Jour. Ceol. Soc. Japan,
vol. 64, p. 265-266 (in Japanese).
- - and - - (1959a): On the Inai Group of
the Lower and Middle Triassic System.
Contr. Inst. Ceol. Paleont., Tohoku Univ.,
no. 50, p. 1-69 (in Japanese with English
abstract) .
- - and - - (1959b): On some Triassic
ammonites from Isatomae Formation.
Japan. Jour. Ceol. Ceogr., vol. 30, p. 97103.
Pakistani-Japanese Research Group (1981):
Stratigraphy and correlation of the marine
Permian-Lower Triassic in the Surghar
Range and Salt Range, Pakistan. Kyoto
Univ., p. 1-25.
Renz, C. (1928): Ober einige untertriadischeAmmoniten-fauna von der Keinasiatische
Insel Chios. Eel. geol. Helv., vol. 21, p.
154-156.
Renz, C. and O. Renz (1947): Obersicht tibereine untertriadische Ammonitenfauna vonder .Insel Chios (Griechenland). Verhandl.

385

Naturforsch. Ces. Basel, vol. 58, p. 58-79.
- - and - - (1948): Eine untertriadischeAmmoniten fauna von der griechischen
Insel Chios. Schweiz. Palaeont. Abh.,Mem. Suisses de Paleont., vol. 66, p. 198.
Shiida, I. (1939): On the geology of Kesennuma-cho and its environs in Miyagi
Prefecture. Contr. Inst. Ceol. Paleont.,
Tohoku Univ., no. 33, p. 1-72 (in Japanese).
Spath, L. F. (1930): The Eotriassic invertebrate fauna of East Greenland. Med.
om Cr(!Jnland, vol. 83, p. 1-90.
- - (1934): The Ammonoidea of the Trias(1) : Catalogue of the Fossil Cephalopoda
in the British Museum (Nat. Hist.), Pt.
4, p. 1-321.
Tozer, E. T. (1965): Lower Triassic stages
and ammonoid zones of Arctic Canada.
Ceol. Surv. Canada, Paper 65-12, 14p.
Wang, Yi-gang. (1978): Latest Early Triassic
ammonoids of Ziyun, Guizhou, with noteson the relationship between Early andMiddleTriassicammonoids.
Acta
Palaeont. Sinica, vol. 17, no. 2, p. 151177 (in Chinese with English abstract).
- - and He, G. (1976): Triassic ammonoids
from the Mount Jolmo Lungma Region.
In Report of Scientific Expedition in the
Mount Jolmo Lungma Region-Palaeontology, Pt. 3- p. 223-438 (in Chinese).
Zhao, J. (1959): Lower Triassic ammonoids
from Western Kwangsi, China. Palaeont.
Sinica, N. S., vol. 9, no. 145, p. 1-355.

::::~~Ucil1i;ltijo) 7 :/.:f::t" -1' r 21ll1, Procarnites kokeni (Arthaber), Eosturia towaensis
gen. et sp. nov. ~WH!Ii~t;J::!1J!t!!*1R~J:: IJ~JIiIt"tGo ;:;(L~0)7 :/.:f::t"-1' r ~t. Scythian;Itij;!; G'" ~t. Spath ian *;Itij~flil~ 1...., 1:.1iil~~i¥.Jt:.~t. Subcolumbites perrinismithi '11ft:. ~;l:;(LG o %ft\!i¥.JifH;&, ¥.ft:.~~O)¥.fr;&~t.~~ Eosturia i.J~::::1!Ucilfj;ltijo) Procarnites c::::~*,c9=t;ltijo) Sturia O)9=tr",'~~-c-;!; G1iJfjgl1:~~IJti:"t Go
1&:mtt;i'fJ • :7kJ1;:~z.

*Trans. Proc. Palaeont. Soc. Japan, N. S., No. 127, pp. 386-392, pI. 61, September 30, 1982

751. MAZAPHYLLUM (RUGOSA) FROM THE SILURIAN OF JAPAN*
MAKOTO KATO
Department of Geology and Mineralogy, Faculty of Science,
Hokkaido University, Sapporo 060

Abstract. Mazaphyllum is a thamnasterioid, cystiphyllid rugose coral recorded
first from Australia. It is now known also from Kazachstan, Arctic Canada andJapan, and ranges from ?Wenlockian to Lower Devonian. A new species, M. mirum
is described from the Silurian Kawauchi Formation in the Kitakami mountains, N. E.
Japan.

this interesting coral for study, and toProfessor Paul Copper of Laurentian
University, Canada, for critically reading
the paper in manuscript. Photographs
are the work of Mr. Sumio Kumano of
Hokkaido University.

Introduction

A small fossil collected by Mr. F.
Murakami of Ohfunato several years ago
in the Higuchizawa valley, Ohfunato city,
Iwate Prefecture was later presented to
Dr. H. Kimura of Ohfunato, who considered the specimen a Silurian stromatoporoid. In looking through Kimura's
collection of stromatoporoids Dr. K. Moriof Tohoku University found that the
specimen was not a stromatoporoid but
might be a rugose coral. I was thenasked to identify it, and the specimen
turned out to be a new species ofMazaphyllunz. This genus was originallyestablished from Australia, but has notbeen commonly known from elsewhere.
The occurrence of Mazaphyllum in Japanis therefore interesting. The systematic
position of Mazaphyllum is discussed
below.

Systematic description

Phylum Coelenterata Frey &Leuckart, 1847
Subphylum Cnidaria
Hatschek, 1888
Class Anthozoa Ehrenberg, 1834
Order Rugosa Milne-Edwards &Haime, 1850
Suborder Cystiphyllina
Nicholson, 1889
recognize eight families within thesuborder Cystiphyllina. They are listed
in the following tabular key:

Acknowledgements

I acknowledge my thanks to Dr. Hozue
Kimura of Ohfunato Hospital for donating

Rugose corals with acanthine septa ......... .
. . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Cystiphyllina
Without tabulae, without dissepiments.

* Received February 17, 1982; read June 26,
1982, in Sapporo.

386

751.

Mazaphyllum (Rugosa) from the Silurian of Japan

Septal spines sparse and irregular. Corallum small, ceratoid ................ .
· . . . . . . . . . .. Family Primitophyllidae
Septal spines regular. Corallum small,discoid or patellate. . .............. .
· . . . . . . . . . . . .. Family Palaeocyclidae
With tabulae, without dissepiments.
Tabulae may be complete or incomplete.
· ............. Family Tryplasmatidae
With cystosepiments.
Operculate.
Corallum calceoloid. . .............. .
................ Family Calceolidae
Corallum pyramidal. ............... .
. . . . . . . . . . .. Family Goniophyllidae
Non-operculate.
Septal spines short. Tabularium anddissepimentarium may be differentiated ........ Family Cystiphyllidae
Septal spines fused to form partly
platy septa .. Family Digonophyllidae
With tabularium and dissepimentarium
differentiated.
With long septal spines. Differentiation
between tabularium and dissepimentarium may be not clear ............ .
· ............. Family Holmophyllidae

Family Holmophyllidae Wang, 1947
(nom. trans!. Ivanovsky, 1968:
pro Holmophyllinae Wang, 1947)
Diagnosis: Cystiphyllid rugose corals
typically with tabularium clearly differentiated from dissepimentarium_ Septal
spines are relatively long and pierce
dissepiments.
Genera: Within the limit of the above
definition, the following genera appear to
be referable to the Holmophyllidae. The
possibility that several of these genera
may be synonymous is noted.
Solitary ..... . Holomophyllum Wedekind, 1927
?Hedstroemophyllum Wedekind,
1927?Gyalophyllum Wedekind, 1927
Spinolasma Ivanovsky, 1965

387

Gukoviphyllum Sytova, 1968
Holmophyllia Sytova, 1968
Mesouralinia Shurygina, 1971
Fasciculate .... Nipponophyllum
Sugiyama,
1940
Baeophyllum Hill, 1940
Dendroholmia
Spas sky&
Kravtsov, 1974
Cerioid ........ ?Storthygophyllum Weissermel,
1894
Xiphelasma Smith & Lang,
1931
Plocoid ........ ?Cystiphorolites Miller, 1889
Mazaphyllum Crook, 1955
Aksarlinia Kaplan, 1975

Genus Mazaphyllum Crook, 1955
1955 Mazaphyllum Crook, p. 1052
1973 Mazaphyllum, Cotton, p. 125
1975 Aksarlinia Kaplan, p. 67
1976 Mazaphyllum, McLean, p. 298
1977 Mazaphyllum, Spassky, p. 70
1981 Mazaphyllum, Hill, F. 107

Type species (by original designation):
Mazaphyllum cortisjonesi Crook, 1955
Generic diagnosis:
Thamnasterioid

Holmophyllidae.
Included species:
Mazaphyllum cortisjonesi Crook ?Wenlockian
to ?Ludlovian of New South Wales,
Australia (Crook, 1955; McLean, 1974,
1976)
Aksarlinia concavotabulata Kaplan?Gedinnian of Central Kazachstan (Kaplan in
Menner (ed.), 1975)
Mazaphyllum mirum Kato, n. sp. Silurian,Kawauchi Formation, Kitakami mountains, N. E. Japan (this paper).

Distribution: ? Wenlockian to Lower
Devonian. East Australia, Kazachstan,Japan and Arctic Canada (Pridolian
according to McLean, 1976).
Discussion: Crook (1955) clearly indicatesthat Mazaphyllum is a member of cystiphyllid corals. It is characterized by388

Makoto KATO

thamnasterioid corallum, dimorphacanthinesepta and sagging tabulae. Although
Crook does not assign the genus to any
family, he suggests some relationshipexists between Mazaphyllum, Holmophyllumand Hedstroemophyllum.
Ivanovsky (1965) merged Mazaphyllum
with query to Palaearaea of the Calostylidae, having perforate septa. Since
Mazaphyllu1ll has distinctly acanthinesepta, Ivanovsky (1973, 1975) later placed
Mazaphyllunl within the Holmophyllidae(nom. transl. Ivanovsky, 1968, 1972), which
procedure I will follow.
McLean (1974) put Mazaphyllum in the
Cystiphyllidae. Later, he (1976) recognized
two subfamilies of the Cystiphyllidae,
namely the Cystiphyllinae and Digonophyllinae, and placed Mazaphyllum in theformer subfamily, which Hill (1981) andI would divide into two families, theCystiphyllidae and Holmophyllidae.
Spassky saw the importance of coloniality in rugosan classification and in1977 relegated the position of Mazaphyllum
to his Superorder Associata, Order Zonastraeida, Suborder Zonastraeina, Family
Microplasmatidae,
Subfamily
Microplasmatinae. But, this procedure results
in a seemingly unnatural grouping. My
classification of cystiphyllids is tabulated
above.
Crook (1955) compared his Mazaphyllum
with other plocoid rugosa of the Silurian
such as Arachnophyllum and Zenophylla.
The completely thamnasterioid corallumand sagging tabulae of Zenophylla aresimilar to those of Mazaphyllum, but theformer has platy septa. Arachnophyllum
also typically has platy septa and uparchedtabulae, so it is distinguishable from
Mazaphyllum. The problem is that insome forms of Arachnophyllum theperipheral part of the septa may be split
into series of discrete trabeculae (see forexample McLean, 1975). Whether acan-thine septa are stable and reliable morphological features or not should betested further. We can name anotherexample in the Cystiphyllidae and Digonophyllidae.
McLean (1974, 1976) compared his
Angullophyllum with Mazaphyllum, but
the former has a cerioid corallum, shortacanthine septa and uparched tabulae.
Angullophyllum is thus closer to Arachnophyllum than to Mazaphyllum.
Kaplan (1975) recognized Aksarlinia to
be rather closely related, and distinguished
Aksarlinia on the basis of the posess ionof holacanthine septa, as compared to thedimorphacanthine septa of Mazaphyllum.
In my opinion, fine structural pattern ofacanthine septa cannot be taken alone asa reliable character to classify Rugosa ingenus ranks. Aksarlinia has a plocoid
corallum, acanthine septa, sagging tabulae
and is best considered as a synonym of
Mazaphyllum.
Cystiphorolites Miller (= Vesicula ria
Rominger) has thamnasterioid, partly
aphroid corallum and is included in the
Holmophyllidae by Hill (1981). The genus
appears to be more similar to Arachnophyllum. Further examination of theform in thin section is neccesary to
clarify its true systematic position(McLean,1974). If it has genuine acanthinesepta, it could possibly be a synonym of
Mazaphyllum.
As mentioned above, Crook (1955)
stated that Mazaphyllum has both holacan thine and rhabdacanthine septa. This
dimorphacanthine nature of Mazaphyllum
is confirmed also by McLean (1974). The
Japanese form of Mazaphyllum cannot be
described with certainty as to its fineacanthine septal structure because of poor
preservation. It may be completely
holacanthine, but the possibility of theinitial presence of rhabdacanths cannot
be excluded, since the external configu-

751. Mazaphyllum (Ru.gosa) from the Silurian of Japanration of each septal spine is sometimes
irregular and crenulated. At any rate, it
is difficult to distinguish genera andspecies of Rugosa by the nature of thefine structure of septa alone. Besides, I
believe that monacanthine to rhabdacan thine septal trends operated in a
number of lineages of cystiphyllids.
More interesting is the pattern of septal
insertion in Mazaphyllum. Septa arearranged more or less radially in the typespecies of both Mazaphyllum and Aksarlinia. But in the new Japanese form
septa are often bundled (Text-figure 1,
A-C). The distinction between major
and minor septa is not clear. A long
septum appears to bifurcate repeatedly,or, short septa were inserted by intercalation, leaning upon long septa. Thus
septal arrangement as a whole is not
cyclical, yet it is not clearly bilateral or
tetrameraI. I am unable to decipher any
regularity in septal insertion. However
the overall pattern is rather similar tothat described by Erina and Kim (1980)
for some corals from the Ordovician ofTienshan. They say that for Tjanshano-389

phyllum and Sumsarophyllum epitheca islacking and septa are porous, showing
peculiar arrangement what they call"fan-like coalescence". They assign thesecorals to the Fungiida of the Scleractinia;
the lack of epitheca might be the resultof peripheral erosion, and "porous septa"
may be a kind of acanthine septa. I
have seen a very similar mode of septal
arrangement on the weathered calicularsurface -of· a' speCimen of Arachn'ophyllwn
typus collected from Wenlock Edge. I
would therefore hesitate to call these
Ordovician corals from Tienshan genuine
members of the Scleractinia. Lavrusewitsch (1971) originally placed his genus
Sumsarophyllum in the family Paliphyllidae. In this connection, the septal
arrangement in the genus Idiophyllum
Cao (Lee et aI., 1975) is very interesting.
In this Chinese Silurian coral the presenceof tertiary septa is recorded. But, in fact
an overall pattern of septal arrangement
in Idiophyllum is quite similar to that of
Sumsarophyllum.
Real tertiary septa
should be distinguished from the septal
pattern now in discussion (Text-figure 2).

~~~~~\~~ ~~ ~B
Text-fig. 1, A-C.

Mazaphyllum mirum Kato. Diagrams showing the pattern of septal
arrangement as it appears i·n transverse ·section.

390

Makoto KATO
compiled by McLean (1976) would indicate,solitary, cerioid and plocoid holmophyllids
may have branched from tryplasmatid
ancestor(s) at or nearly the same time in
the Early Silurian.
Mazaphyllum mirum Kato, sp. nov.
Plate 61, Figs. 1-2; Text-fig. lA-C.

Text-fig_ 2. Diagrams showing thedifference between the genuine tertiary
septa (A) and bundled septa (B).

What appears to be a peculiar mode of
septal insertion in Mazaphyllum is now
known to occur at least in some otherancient corals, and the mode may haveoriginated in corals as old as Ordovician.
Septal arrangement should be traced
ontogenetically in each coral in order toclearly understand the true mode of septal
insertion.
Crook (1955) commented originally thatthe range of the genus Mazaphyllum isfrom the Lower to Middle Silurian.
But McLean (1974) later stated that thegenus is common in East Australia from
? Wenlockian through ? Ludlovian strata.
Further he mentioned (1976) on the occurrence of the genus from Arctic Canada
in rocks of ? Pridolian age. This latteroccurrence is not described or illustrated
as yet. Taking Aksarlinia and thepresent Japanese form, the genus is now
known from Australia, Kazachstan, Arctic
Canada and Japan, in rocks from
? Wenlockian to Lower Devonian age.
The phylogeny of Mazaphyllum is notknown. Holmophyllids in general may
have been derived from some type of tryplasma tid. This course is suggested byobserving ontogenetical changes in Nipponophyllum (Kato, in press). As stratigraphical range of holmophyllid genera

Material: A small, peripherally weathered fragment of a colony, UHR 30519(Holotype), with black limestone matrix.
Preserved portion of the colony measures
8x4x2 cm. Collected by F. Murakami,
as a float derived from the Silurian
Kawauchi Formation, at Sugiyama One,
Higuchizawa, Ohfunato city,
Iwate
Prefecture, Japan.
Derivation of the specific name: mira
(Latin)-wonderful.
SPecific diagnosis: Mazaphyllum withsmall tabularia (¢=1-1.5 mm).
Description: Corallum small, compound,massive and thamnasterioid. External
shape and surface character of thecomplete corallum unknown. Holotheca
not preserved.
In transverse section, series of acanthinesepta are confluent from one corallite tothe other to reveal the completely
thamnasterioid nature of the corallum.
The polygonal configuration of a corallite
may only be realized by tracing the
middle or junction parts of these seriesof confluent acanthine septa. The sizeof each corallite thus outlined may reachas long as 14 mm in minimum diameter.
Tabularia appear as calicular pits on thesurface of the corallum: eight such pits
are counted in a space of 8x3 cm.
Diameter of the tabularium is 1 to 1.5 mm,
but it is generally not very welldifferentiated from the dissepimentarium.
Septa are acanthine. As many as 93
series of acanthine septa are counted in a

751.

Mazaphyll'Ltm (Rugosa) from the Silurian of Japancorallite. They are protruded into thetabularium. Their septal arrangement isdifficult to decipher, but it is not typically rugosan, in which four places of
new septal insertion are usually clearly
indicated.
Instead, septal series areapparentIy bifurcated peripherally or with
one series often leaning on another, thus
multiplying the total number of the seriesof acanthine septa. Fine structure of
septa is not clear, but it appears to beholacanthine. In places each spiny rod
has a slightly indented surface suggestingthat they may have originally been
rhabdacanthine. No axial structure ispresent.
In longitudinal section, the dissepimentarium is wide, consisting of globose
or slightly flattened, small dissepiments
which are pierced by vertically straight,
long septal spines. Spines are sometimes a little divergent in their arrangement especially near the boundary
between the tabularium and dissepimentarium, where dissepiments are somewhat
arched upwards. Dissepiments become
smaller near the septal spines, so thatthey are inosculating between septal
spines. Spines are occasionally seenbifurcating. Axial portion of septal
spines protrudes for a relatively long
distance into the tabularium, and steeply
dipping outwards. Tabularium is notwell differentiated from the dissepimentarium, and is composed of incomplete,sagging tabulae. No trace of corallite
wall is observed.
Comparison: Assignment of the Japanese
species to the genus Mazaphyllum is clear.
The new species is readily distinguishable from other species of the genus,
namely M. cortisjonesi and Aksarlinia
concavotabulata, in having much smaller
tabularia, which are only 1-1.5 mm indiameter, compared to 4-4.5 mm in thetype species and 3-3.5 mm in Aksarlinia.

391

Also septal spines fall short of the centre
of corallite, thus leaving a wide open
space in the tabularia in the other two
species; in the new species septal spines
protrude distantly into the tabularium.
Peculiar septal arrangement is not soconspicuous in the other two species, inwhich it is more radial in nature.
References
Provisional titles in English are given to
those articles written in Chinese and Russian.
Cotton, G. (1973): The rugose coral genera.
Elsevier, Amsterdam, 358 p.
Crook, K. A. W. (1955): Mazaphyllum, a new
cystiphyllid coral from the Silurian of
New South Wales. Jour. Pal., vol. 29,
p. 1052-1056.
Erina, M. V. & Kim, A.!, (1981): On someOrdovician Scleractinia-like corals fromthe South Tien-shan. Acta Pal. Polonica,
vol. 25, nos. 3-4, p. 375-379, pis. 18-21.
Hill, D. (1981): Treatise on Invertebrate
Paleontology, Part F, Supplement 1,
Coelenterata: Anthozoa, Subclass Rugosa,
Tabulata. Geol. Soc. America, F 1-762.
!vanovsky, A. B. (1965): "Ancient Rugosa".
"Nauka", Moscow, 151 p. (in Russian).
- - (1968): "Rugosan evolution in Ordovician and Silurian".
"Doklady Soviet
Ceol.",
XXIII
Session,Int. Ceol.
Congress, p. 80-88 (in Russian).
- - (1972): The Evolution of the Ordovician
and Silurian Rugosa. 1968 IPU Proc.,
XXIII Int. Ceol. Congress, p. 69-77.
- - (1973): "The system of Rugosa". Trans.
Inst. Ceol. & Ceophysics, Siberian Branch,
Akad. Nauk USSR, Fasc. 47, p. 76-81.
(in Russian).
(1975): Rugosa. Ibid., Fasc. 242, 123 p.
Kaplan, A. A. (1975): See Menner, V. V.
(ed.) (1975).
Kato, M. (in press) : Nipponophyllum (Rugosa)
from Gotland. Stockholm Contr. Geology.
Lang, W. D. & Smith, S. (1927): A Critical
Revision of the Rugose Corals describedby W. Lonsdale in Murchison's "Silurian
System". Quart. Jour. Ceol. Soc., vol. 83,

392

Makoto KATO

p. 448-490, pIs. 34-37.
Lavrusewitsch, A.1. (1971): "New Late
Ordovician Rugosa from ZerabshanGissar mountain region".
Palaeont.
Zhurnal, 1971, no. 4, p. 3-7, pI. 1. (inRussian) .
Lee, H. H., Sun, L. S., Chou, C. C. & Young,
C. Y. (ed.) (1975): "Stratigraphy of the
Early Palaeozoic Era in the western
Ta-pa
mountains".
section of the"Geology Press", 372 p. (in Chinese).
McLean, R. A. (1974): Cystiphyllidae andGoniophyllidae (Rugosa) from the Lower
Silurian of New South Wales. Palaeontogr., Abt. A, Bd. 147, Lfg. 1-3, S. 138, Taf. 1-6.
(1975): Lower Silurian Rugose Corals

from Central New South Wales. Jour.
Roy. Soc. N. S. W., vol. 108, p. 54-69,
pIs. 1-6.
- - (1976): Genera and stratigraphic distribution of the Silurian and Devonianrugosecoral
familyCystiphyllidae
Edwards & Haime. Ceol. Surv. Canada,
Paper 76-18, p. 295-301.
Menner, V. V. (ed.) (1975): "Characteristic
fauna of the Silurian-Devonian boundary
deposits of Central Kazachstan". Moscow
University, "Nedra", Moscow, 248 p. (inRussian).
Spassky, N. Ya. (1977): "Devonian Rugosaof the USSR". Leningrad University,
Leningrad, 344 p. (in Russian).

:!6--'fJJlldeJi'r}l!ftffitlli lJ lRO) -/)v )v*)II P:JJI J: I), ggM-IJ-:/::( 0) 1ffifi, Mazaphyllum mirum
Kato ~~~. Mazaphyllum ,\1itb' Cystiphyllid '1:;1., Q i: C ~~ 1.:, Cystiphyllina W § 0)
5tJiJ:::. "?\" -c t ~;h,t..:. ffifit:::.~ ~;h,Q ~~:IlPA}!It.~At.l: t 0) '1:;1., Q. Mazaphyllum ~It.,
E:<$:,"h-r!7-, :;t-;t, r =j Vi',:lilO)t:p$-/JV/v* (?)-"f$7';f.:/*J: 1)~~;h,Q.

Explanation of Plate 61
Figs. 1-2. Mazaphyllu7n mirum Kato, sp. nov.; all figures x4. 1: Longitudinal section. 2:
Transverse section showing 'Completely thamnasterioid corallum. Note the type of septal
insertion. UHR 30519 (Holotype), Silurian, Kawauchi Formation.

J(ATO:

Mazaphyllum (Rugosa) from Japan

Plate 61Trans. Proc. Palaeont. Soc. Japan, N. S., No. 127, pp. 393-418; pIs. 62-65, September 30, 1982

752.

THE BIVALVE FOSSILS FROM THE CRETACEOUS
FUKIGOSHI. . FORMATION OF THE MONO BE, .. 'AREA, SHIKOKU~~, MASA YUKI TASHIRO and TOMOKO MATSUDA
Department of. Geology, Faculty of Science, Kochi University, Kochi 780

Abstract. This paper deals mainly with the description of the bivalve fossils
from the Fukigoshi Formation, which is composed of muddy sediments in the lower
part and of sandy ones in the upper part and distributed at and near the Nagase
Dam, Monobe area, Shikoku., 22 genera and 24 species including 4 new species, i. e'., •Nucula (Pectinucula) kochiensis sp. nov.,' Acila (Truncacila) monobensis sp. nov.;'
Portlandia (s.l.) nagaseana sp. nov. anp fya:no'navis pseudocarinata' sp. nov., are'describedJrom the upper part of the,formation. The species composition of bivalve,fauna suggests shatIow 'marine or pure marine conditions in the Lower Cenomanian. 'This fauna resembles closely that of the °Mif~ne Group in Central Kyushu, in theoccurrence of many common species between them. Presumable geologi'cal age of the
Fukigoshi Formation is with the range from the Upper Albian "t6' t-lie "LOwer
Cenomanian. On the other hand the Horonbetsu Formation in northern" Hokkaid'b IS
probably correlated with the upper part of the Fukigoshi Formation, bec~use ~(t~e "occurrence of Pterotrigonia (? Scabrotrigonia) imanishii (Nakano).
" a 0

trace-fossils and "oyster" beds. On thematerial of our collection from these
localities, the bivalves consisting of 22
genera and 24 species including 4 new
species, are described in this paper, with
their biostratigraphical implications.
The specimens (KSG) described in thispaper are preserved in the Faculty of
Science, Kochi University (Kochi 780).
Before going further, we wish to express
our hearty thanks to Professor Emeritus
Tatsuro Matsumoto of Kyushu University
for his continuous guidance and reading
the first draft. We also wish to express
our sincere thanks to Professor Minoru
Tamura of Kumamoto University for his
valuable suggestion. Thanks are extended
to Mr. Takeshi Kozai of Odochi Elementary school who kindly supplied us several

Introduction

Recently the Fukigoshi Formation has
been discriminated by Tashiro et al. (1981)
from the Lower Cretaceous Hagino Formation, which is exposed at Hagino of theMonobe area, because of the distinctionof the molluscan faunas and the differencein geological age between the Fukigoshi
and Hagino Formation.
The Fukigoshi Formation is distributed
narrowly at and near the Nagase Dam of
Odochi in the Monobe area, Shikoku (seeThree molluscan fossil
Text-fig. 1).
localities are recognized in the dark-grayshale of the Upper Member of the formation in addition to several localities of* Received February 19, 1982; read October
4, 1981 in Hiroshima.

393

394

Masayuki TASHIRO and Tomoko MATSUDA
/
/

,
/

/

/

Nagase F.

/
/

,
/

!

Fukigoshi F.

··· ....... .. ..
. ... .

... . .

. . ·. ..
...
·.
.. ..

NagaseText-fig. 1. Geological map and fossil localities of the Fukigoshi
Formation in the Monobe Area.

specimens from loco 3.

Geological setting
The Fukigoshi Formation typically crops
out on the southern bank of the Monobe
River at and near the Nagase Dam, about
1500 m northwest of Odochi, Monobe area,
Kochi Prefecture. The columnar section
measured along the ri ver Monobe isshown in Text-fig. 2.
The Fukigoshi Formation, about 380 m
in total thickness, is divided into theLower and Upper Members. The strata
take the general attitude of N700E in
strike and about 80° to the north in dip.
The Lower Member, about 210 m inthickness, is mainly composed of darkgray shale or siltstone, but several bedsof fine grained sandstone, about a few
meters in each thickness, are intercalated
at the middle part. On its southern Ci. e.,lower) side this member is in contact
with another unit of dark-gray shale of
the Jurassic Torinosu Group. The contact
is a strike fault. An ammonite, Anagaudryceras cf. sacya (Forbes), was once

752.

t .. .

Cretaceous bivalves from the Monobe Area--~----- ~W-:......... :.... -

c
-u
-u

.~'-~~~'i; -Zoophycos sp.

m::0

Loc. 3~~3-Loc.2

ill

~

m

.:"~-~~~~ _Zoophycos sp.
. . .~. ~:. -"Ostreo"

~

CD

m

::0

II

- - - -.... ::.. ::..;.... "~~~. ::5.=~==-:'~ ...... : ..

I---

"Ostreo"Zoophycos sp.

---.:=::o::~~:: -Zoophycos sp.

~::' .........::;; conglomerate
shale

r

o

~

m

SOm

::0

3::

m
3::

CD

m

::0

o
'<:':.:'.: :: sandstone:=::;--:::=: --- Anogoudryceras
--- -

,

1-:=:=::.:::: siltstone

cf. sacya395

collected from the probable lower part ofthis member (Matsumoto, 1982).
The Upper Member, about 170 m inthickness, is composed of five sedimentary cycles, each of which is composedof the conglomelate and light gray sandstone in the lower subdivision, the alternations of dark-gray siltstone and finegrained sandstone in the middle subdivision and dark-gray shale in the upper
subdivision. Thin "oyster" beds are often
found in the conglomelate of the lower
subdivision of each cycle. The siltstoneof the middle subdivision in each cycle
except for the second one (see Textfig. 2) (cycle II), is characterized by theoccurrence of trace fossils, Zoophycos sp .
Three fossiliferous beds are recognizedin the Upper Member of the Fukigoshi
Formation in addition to the "oyster"beds.
The lower fossiliferous bed (loc. 1)
appears in the shale of the upper subdivision in the second cycle (cycle II).
Parvamussium cowperi yubarense (Yabeet Nagao) is known from the bed.
The middle bed (loc. 2), which ischaracterized by many species of bivalvesand gastropods, appears in the shale ofthe upper subdivision in the third cycle(cycle III). The bivalve fossils are as
follows: Nucula (Pectinucula) kochiensis
sp. nov., Acila (Truncacila) monobensis sp.
nov., Mesosaccella mifunensis Tamura,Portlandia (s.1.) nagaseana sp. nov.,
Matsumotoa unisulcata (Amano), Nanonavis
pseudocarinata sp. nov., Arca (Eonavicula)sp., Glycymeris (Pseudoveletuceta) d.
mifunensis Tashiro, Septifer d. mifunensis
Tamura, Entolium sp. d. E. obovatum(Stoliczka), Nippononectes kozaii Tashiro,
Anomia sp. aft. A. foldia Tamura,
Text·fig. 2. The columnar section of
the Fukigoshi Formation. I-V: Sedimentary
cycles in the Upper Member.

396

Masayuki TASHIRO {Lnd Tomoko MATSUDA

Crassostrea
kawauchidensis
Tamura,Pterotrigonia (? Scabrotrigonia) monobeana
Tashiro et Kozai, P. (? Acanthotrigonia)
mashikensis (Tamura et Tashiro), Myrtea(s.l.) sp., Thetis sp. aff. T. japonica (Yabeet Nagao), Anthonya sp. d. A. mifunensis
Tamura, ? Cymbophora sp., Eomiodon
matsubasensis Tamura, Goshoraia crenulata(Matsumoto) and Legumen sp..

The upper fossiliferours bed (loc. 3) isinserted in the shale of the upper subdivision in the fourth cycle (cycle IV).
Several bivalve species, i. e., Acila (Truncacila) monobensis sp. nov., Mesosaccellamifunensis Tamura" Nanonavis pseudocarinata sp. nov., Nippononectes kozaii
Tashiro, Parvamussium cowperi yubarense(Yabe et Nagao) and Pterotrigonia(? Scabrotrigonia)
imanishii (Nakano),
commonly occur in this bed.
On the north side the Upper Member
is conformably overlain by the basal
conglomelate of the Nagase Formation(Katto and Suyari, 1956; Tashiro et aI.,
1982), which ranges from the (upper)
Lower Cenomanian to the Upper Cenomanian (Matsumoto and Tashiro, 1982).
Systematic description
Class Bivalvia
Subclass Palaeotaxodonta
Order Nuculoida
Family Nuculacea Gray
Genus Nucula Lamarck, 1799
Subgenus Pectinucula Quenstedt, 1930
Nucula (Pectinucula)kochiensis, sp. nov.
Plate 62, Figs. 7, 11-15, Text-fig. 3

external mould, from loco 2; para types,
KSG 3112-KSG 3114, from the same type
locality.
Descript£on :-Shell small, trigonal ovate,
loriger than 'high, moderately inflated;umbo small,' oplsthogyrous, not prominent,
located at, two' thirds from front of thevaiv~; anterior, dm:sal margin weakly
arched; an'terior- margin well rounded;
ventral margin broadly arched; posterior
margin not discriminated clearly fromposterior dors'al margin, very short,forming nearly right angle with theventral margin; posterior dorsal margin
nearly straight, but weakly concave near
the umbo; umbonal angle about 100·;
pseudoluJ?ule narrow, strongly depressed;
posterior carinal ridge well elevated,weakly concave, extending from the umbo
to the postero-ventral corner; disk
ornamented with about 50 radial ribs
wh'ich are round-topped,' broader thantheir inters paces ; hinge line about' twothirds of the valve length; anterior partof the hinge about twice as long as
posterior part, weakly arched, with 10 ormore small hooked teeth; posterior partof the hinge nearly straight, with about
6 or more hooked teeth; resilifer small,with an opisthocline axis; posterior
adductor scar stronger than anterior one;
inner margin provided with about 45
dense crenulations; pallial line weakly
impressed; growth lines on the disk very
weak.
Measurements (in mm.):
Specimen
KSG 3111, R.
ex. mO\lld
KSG 31iZ, L.
'ex. iho,uld
KSG 3113, R.
in. mould
KSG 3114, R.
ex. mould

Length Height Thickness
16.8 ' 13'.8

4.1

9.3

7.0

3.1

12.4

10.2

ca 6'9

7.5

Observation :--:The i-adial' ribs on thedisk are strongly' impressed; , The, hing.e".

Material :-Holotype, KSG 3111, right

1.7'"'""'l752.

Cretaceous bivalves from the =Monobe Area

397

AcilaI(Truncacila) monobensis, sp. nov.
Plate 62, Figs. 1-6, 8-10, Text-fig. 4
1976. Acila (Truncacila) sp. aff. A. demessa
Finley; Tashiro, Palaeont. Soc. Japan.
Sp. Pap., no. 19, pI. 1, figs. 16-18. (nodescription)

Text·fig. 3. Nucula (Pectinucula)kochiensis, sp. nov.

teeth are less numerous for the genus.
This species is undoubtedly referable tothe subgenus Pectinucula Quenstedt (1930),
judging from the distinct round-topped.radial ribs on the disk.
Comparison :-This species resembles
Nucula (Pectinucula) pectinata Sowerby(W oods, 1899; Quenstedt, 1930), typespecies of Pectinucula, from the Upper
Greensand of England, in its distinct
radial ribs, but differs in having a moreclearly triangular outline, more numerous
radial ribs and less numerous hinge teeth.
This is discriminated from Nucula (Nucula)amanoi Tashiro (1976), from the Himenoura Group of Kyushu, by its less rostrated
posterior ventral part and the roundtopped radial ribs. Nucula (Pectinucula)radiatocostata Nagao (1932), from theUpper Ammonite Beds of South Saghalien,
is distinguishable from this species in its
large valve and variable features of theradial ribs on the disk.
Occurrence :-Common at loco 2 and loc.3.

Material :-Holotype, KSG 3101, rightvalve, from loco 2; paratypes, KSG 3102KSG 3109, from the same type locality.
Description :-Shell medium to small,
trigonal ovate in outline, a little longer
than high, moderately inflated; umbo
opisthogyrous, slightly elevated fromdorsal margin, located at about threefifths from front of the valve; apicalangle about 90·; anterior dorsal margin
very weakly arched, about a half l~ngthof the valve; anterior margin wellrounded; ventral margin moderately
arched; posterior margin very narrow,discernible clearly from posterior dorsal
margin; posterior dorsal margin nearlystraight or slightly concave; pseudolunule
indistinct; escutcheon narrow; strongly
depressed; disk ornamented with numerous
diverging ribs which are plain and wider
than interspaces; a line bisecting chevron

Genus Acila Adams et Adams, 1858
Subgenus Truncacila Grant.et Gale, 1931

Text-fig. 4. Acila (Truncacila)
monobensis, sp. nov.

398

Masayuki TASHIRO and Tomoko MATSUDA

generally located on the central line orslightly anterior to that line; hinge line
about two thirds of valve length; anterior segment of hinge long, about twice ofthe posterior one, weakly arched, with.about 10 or more strong and hookedteeth; posterior segment nearly straightor slightly concave, with about 6 hookedteeth; resilifer opisthocline, small; anterior and posterior adductor scars strongly
impressed; pallial line simple; inner
margin finely crenulated; growth lines
nearly indistinct.
Measurements (in mm.):
Specimen
KSG 3101, R.
valve
KSG 3102, R.
ex. mould
KSG 3104, R.
valve
KSG 3106, R.
valve
KSG 3107, R.
valve
KSG 3108, L.
valve
KSG 3109, R.
in. mould

Length Height Thickness
19.9

14.4

4.8

12.3

8.2

2.8

25.3

14.4

16.2

13.2

4.9

12.8

11.5

2.9

11.5

3.5

19.4

13.1

Observation :-The ribs posterior to thebisecting line of chevron number about
25, are set in nearly parallel with theposterior carina, which extends fromumbo to postero-ventral corner and is
weakly concave. The ribs anterior to
the line are subradial, countable about 20
in number, and sometimes bifurcate nearanterior ventral part on the mature
specimens. The apical angles of thechevrons are about 50· or more on themature stage.
Comparison :-The specimens (KE 2029,
GK 6989a and GK 6989b in Tashiro, 1976)
from the Cenomanian Mikasa Formationof Hokkaido, are undoubtedly conspecificwith the present specimens from the
Fukigoshi Formation in having the samecharacters. This species is very similar

to Acila (Truncacila) demessa Finley fromthe Upper Cretaceous of California(Schenck, 1936), in its subtrigonal outline
and the location of the bisecting line. A.
(T.) demessa is, however, characterized
by weaker chevron-shaped ribs and moreposterior location of the umbo than thoseof this species. It is akin to Acila(Truncacila) schencki Stoyanow (1949)
from the Lowell Formation of Arizona,in its triangular outline, but differs in its
numerous ribs. Acila (Truncacila) bivirgata(Sowerby) from the Lower Greensand of
England (Woods, 1899; Schenck, 1936), ischaracterized by more numerous ribs On
the disk than those of this species.
This species is discriminated easily fromAcila (Truncacila) hokkaidoensis (Nagao),
from the Upper Cretaceous of Japan (see,Tashiro, 1976), which is characterized by
the protruded posterior margin.
Occurrence :-Abundant at loco 2 and loco 3

Superfamily Nuculanacea
Adams et Adams
Family Malletiidae Adams et Adams
Genus Mesosaccella Chavan, 1946
Mesosaccella mifunensis Tamura
Plate 62, Figs. 19-22
1976. Mesosaccella mifunensis Tamura, Mem.
Fac. Educ. Kumamoto Univ., no. 25,
nat. scL, p. 49, pI. 1, figs. 25-30.

Material :-KSG3127-KSG 3130, internalmoulds of right valves; KSG 3125-KSG
3126, internal moulds of left valves; KSG
3122-KSG 3123, right valves; all fromloco 2.
Measurements (in mm.):
Specimen
KSG 3122, R.
valve

Length Height Thickness
8.4

6.1

2.4

752.
KSG 3123, R.
valve
KSG 3125, L.
in. mould
KSG 3126, L.
in. mould
KSG 3127, R.
in. mould
KSG 3130, R.
in. mould

Cretaceous bivalves from the Monobe Area

7.6

4.9

8.4

5.0

6.6

4.9

8.8

5.6

9.0

4.9

399

1.2

Remarks :-Numerous specimens of thisspecies are before us. This species isconspecific with Mesosaccella mifunensis
Tamura (1976), from the Mifune Groupof Central Kyushu, which was welldefined by Tamura.
Occurrence :-Abundant at loco 2; common at loco 3.
Family Nuculanidae Adams et Adams
Genus Portlandia Morch, 1857

Portlandia (s. I.) nagaseana, sp. nov.
Plate 62, Figs. 23-25, Text·fig. 5

Material :-Holotype, KSG 3132, internalmould of right valve; paratypes, KSG
3133-KSG 3135, internal moulds of rightvalves ~ all the specimens are collectedfrom loco 2.
Description: - Shell small, elongately
ovate, somewhat rostra ted to posterior,
weakly inflated; umbo small, nearly
orthogyrous, not prominent, pointed atabout two fifths from front of the valve;anterior dorsal margin short, slightly
convex; anterior margin semi-circular;
ventral margin broadly arched; posterior
margin narrowly rounded; posterior dorsal
margin elongated, weakly concave;pseudolunule very narrow, strongly
depressed from an angulated marginal
carina; posterior carina not angulated
but weakly swollen; external surface
nearly smooth except for fine growthlines; hinge plate long with about two
thirds of the valve length but very

Text-fig. 5. Portlandia (s. I.)
nagaseana, sp. nov.

narrow in breadth with abundant hookedteeth; anterior segment of the hinge
plate shorter than posterior one with
about three fifths in length; resilifer
small, situated under the umbo; bothlateral adductor scars weakly impressed;
pallial line indistinct; inner margin smooth.
Measurements (in mm.):
Specimen
KSG 3132, R. in. mould
KSG 3133, R. in. mould
KSG 3134, R. in. mould
KSG 3135, R. in. mould

Length Height
21.1
14.0
16.3
13.3
9.2
5.5
8.8
5.4

Observation :-The outline of this species
is somewhat variable. The resilifer isshallow and small for Portlandia.
Comparison :-This species resembles
Portlandia sanchuensis (Yabe et Nagao)
from the Ishido Formation of Sanchu
Area (Yabe, Nagao and Simizu, 1926;
Hayami and Oji, 1980), in its features of
the hinge structure and elongated outline,
but differs in its location of the umbo,
which is situated more anterior than of
P. sanchuensis. Portlandia izumensis Ichikawa et Maeda (1958), from the Izumi
Group of A waji island, resembles thisspecies in its elongated outline, butdiffers clearly in its fine oblique striae
on the surface. Portlandia (Cnestriella)
cuneistriata Ichikawa et Maeda, from theIzumi Group and the Himenoura Group,(see, Tashiro and Otsuka, 1980) is distinguishable from this species in its fairly

400

Masayuki TASHIRO and Tomoko MATSUDA

inflated valve and distinct oblique striae
on the disk.
Occurrence :-Common at loco 2.
Family Noetiidae Stewart'. ~:: .:: ' :, :Subfamily Noetiinae Ste'wa·r.f':•... : ..

... : .....:

Genus Mats'urnotoa Okadit, 1958

Matsumotoa unisulcata (A rna no), Plate 62, Figs. 30-32, Plate 65, Fig. 111938. Navicula sp., Matsumoto, jour. Ceol.
, Soc. japan, vol. 45, p. 14, 'pI. 1, figs.
2, 3. :
1956. Breviarca unisulcata Amano, Kumamoto
jour. Sci., ser. B, sec. 1, p. 66, pI. 1,
figs. 2, ,3.
1968. Matsumotoa unisulcata (Amano); Tamura, Tashiro and Motojima, Mem.
Fac. Educ. Kumamoto Univ:, no. 16,
nat. sci., p. 36, text-fig. 1, pI. 1, figs.
1-5.
1968. Matsumotoa unisulcata densestriata
Tamura et Tashiro, in Tamura, Tashiro
and Motojima, Ibid., p. 36, text-fig. 1,
pI. 1, figs. 6-9.
1976. Matsumotoa unisulcata (Amano); Tamura, Ibid, no. 25, nat. sci., pp. 50-52,
pI. 1, figs. 7-16.

Material :-KSG 3148, internal mould ofleft valve, from loco 2; KSG 3149, external mould of left valve, from loco 2.
Remarks :-KSG 3148 is measurred 8.1
mm in length, 4.6 mm in height and 6.5
mm in inner thickness. Another specimen, KSG 3149, is 8.4 mm in length and
5.0 mm in height. These specimens areundoubtedly identified with Matsumotoa
unisulcata (Amano), from the Mifune
Group of Central Kyushu (Tamura, 1976).
They are more closely related in shellform to Matsumotoa unisulcata densestriata
Tamura et Tashiro (1967), which wasrevised as a synonym of Matsumotoa
unisulcata by Tamura (1976), from the

Mifune Group, than Matsumotoa unisulcata
S. S. (Amano, 1956) from the Goshonoura
Group, in their oblique outline and finer,
more crowded hinge teeth on both lateralsegments of the hinge plate. The radialribs on the surface are irregularly spaced
and variable in strength.
Occurrence :-Common at loco 2; darkgray siltstone of the upper part of lIe
Member (by Yamamoto and Hayami, 1971)of the Goshonoura Group at about 300 m
west of Hegushi, Shishijima island,
Kagoshima Prefecture.
Subclass Pteriomorphia
Order Arcoida
SuperfamilY Arcacea Lamarck
Family Parallelodontidae Dall
Subfamily Parallelodontinae Dall
Genus Nanonavis Stewart, 1930

Nanonavis pseudocarinata, sp. nov.
Plate 62, Figs. 16-18, Plate 63, Fig. 10,
Plate 64, Figs. 15-17, 23, Text-fig. 6

Material :-Holotype, KSG 3217, externalmould of left valve, from Sannosawa,
Ikushunbetsu, Hokkaido; a para type, KSG
3216, left external mould, from Hegushi
of Shishijima, Kagoshima Prefecture; theother paratypes, KSG 3142-KSG 3147,
internal and external moulds, from loco 2.
Description :-Shell medium to small,subquadrate in outline, longer than high,moderately inflated; umbo prominent,slightly prosogyrous, located at about athird from front of the valve; hinge
margin elongated, straight; anterior
margin obliquely truncated at an angle
70· to hinge margin, gradually changing
into broadly arched ventral margin but
nearly straight on its posterior half;

752.

Cretaceous bivalves !1'01n the Monobe Area

posterior margin nearly straight, obliquely
truncated, forming an angle of about 120
with hinge margin; postero-ventral corner
generally angulated ; ligament area narrow
but elongated with several chevron-shaped
grooves; hinge area long with each three
anterior and posterior teeth, and smalland short median teeth; the anterior teeth
elongated, subparallel with one another,a little oblique to the horizontal hingeline, inclining towards venter; theposterior teeth elongated, nearly horizontal,
fairly longer than the anterior ones,
parallel with one another; median teeth
about 6 or more in number, converging
toward venter; hinge teeth with finecrenulation; surface ornamented withprimary and secondary radial ribs; theribs narrower than their inters paces,
stronger and less numerous in left valve
than in right valve; posterior carina
angulated; posterior area to the carina
strongly depressed; inner margin smooth;both lateral adductor scars weakly
impressed.

401

0i\!Ieasurements (in mm.):
Specimen
KSG 3217, L.
ex. mould
KSG 3142, L.
ex. mould
KSG 3143, L.
in. mould
KSG 3144, R.
in. mould
KSG 3145, L.
in. mould
KSG 3146, L.
ex. mould

Length He ight Thickness

26.1

18.0

7.0

13.4

8.4

3.6

20. 7

12.3

20.4

10.0

23.5

10.0

14.3

7.9

4.0

Observation :- The radial ribs number
about 70 in right valve and about 40 inleft valve. The posterior carina isangulated, extends from umbo to posteroventral corner, demarcating the boundary
between the inflated disk and the depressed
and flattened posterior area.
Comparison :-This species was listed

T ex t-fig. 6. Nanonavis
pseudocarinata, sp. nov.

at first as "Nanonavis aff . sachaLinensis(Schmidt)" by Tashiro and Yamamoto(1980) based on the specimens from the
Cenomanian formations i. e., the Mikasa
Formation of Hokkaido and the Goshonoura Group of Shishijima, Kyushu. The
specimens from the Fukigoshi Formation
are undoubtedly identified with the socalled "Nanonavisaff.
sachaLinensis(Schmidt)" by the same features . This
species is, however, discriminated from
Nanonavis sachaLinensis (Schmidt), fromthe Urakawan (Coniacian and Santonian)of Japan and Sacha lin, by its angulated
posterior carina, sharply expanded anterodorsal corner and somewhat obliqueanterior teeth.
Nanonavis carinata (Sowerby), from theLower Greensand of England (Woods,
1899), is similar to this species in its
angulated posterior carina, but differs in
its flat-topped and widely spaced radialribs on the disk. It is closely akin to
Nanonavis yolwyamai (Yabe et Nagao)
from the Lower Cretaceous of Japan(Yabe, Nagao and Shimizu, 1926; Hayami,
1965; Hayami and Oji, 1980), in its
features of hinge structure and angulated
posterior carina, but differs in its lessnumerous radial ribs of the right valve,more numerous secondary ribs of the left

402

Masayuki TASHIRO and Tomoko MATSUDA

valve and narrower ligament areawith less numerous ligament grooves.
This species seems to show intermediatecharacters bet weed Nanonavis yokoyamai
and Nanonavis sachalinensis.
Occurrence :-Gray siltstone of thelower-most part of the Mikasa Formation
at Sannosawa, Ikushunbetsu, Mikasa City,
Hokkaido; Lower Cenomanian. Darkgray siltstone of the upper part of theMember lIe (by Yamamoto and Hayami,1971) of the Goshonoura Group at about
400 m west of Hegushi, Shishijima,
Kagoshima Prefecture, Kyushu; Lower
Cenomanian. Common at loco 2 and loco
3 of the Fukigoshi Formation.

long, 13.4 mm high and 4.4 mm thick.
Its internal features are not clear because
the available internal mould is fragmentary. The inner ventral margin is smooth.
This specimen is discriminated from Arca
(Eonavicula) shinanoensis Yabe et Nagao
in Yabe, Nagao and Shimizu (1926), fromthe Shiroi Formation of the Sanchu Area,
and Arca (Eonavicula) prolata Amano(1957), from the Hagino Formation of theMonobe Area, by its strongly laminatedconcentric ribs.
Occurrence :-Rare at loco 2.

Family Glycymerididae Newton
Genus Glycymeris da Costa, 1778

Family Arcidae Lamarck
Genus Arca Linne, 1758

Subgenus Pseudoveletuceta
Tashiro, 1971

Subgenus Eonavicula Arkell, 1929

Glycymeris (Pseudoveletuceta)

Arca (Eo navicula) sp.

d. mi/unensis Tashiro

Plate 64, Fig. 22

Plate 62, Figs. 26-29

Material :-KSG 3161, external mouldof left valve, from loco 2.
Description :-Shell small, elongately
subquadrate, weakly inflated; umbo
prominent, orthogyrous, located at nearlycentral point of horizontal dorsal margin;
anterior and posterior margins weakly
convex, subvertical to the dorsal marginon each side; ventral margin long,horizontal, nearly straight but slightly
concave at the middle part; a shallow
radial sulcus extends from umbo to thecenter of the ventral margin; posteriorcarinal ridge not angulated but wellelevated; surface with numerous laminatedconcentric ribs and abundant fine radialribs; median part of the disk near theradial sulcus somewhat reticulated.
Remarks :-The specimen is 25.7 mm

Compare.1971. Glycymeris (Pseudoveletuceta) mifunensis Tashiro. Trans. Proc. Palaeont. Soc.
Japan, n. S., no. 84. p. 236, text-fig. 6,
pI. 28, figs. 24-30.
1975. Glycymeris (Pseudoveletuceta) mifunensis Tashiro; Hayami, Univ. Mus. Univ.
Tokyo, Bull. no. 10, p. 35, pI. 1, fig. 8.
1976. Glycymeris (Pseudoveletuceta) mifunensis Tashiro, Tamura, Mem. Fac. Educ.
Kumamoto Univ., no. 25, nat. sci., p.
58, pI. 1, figs. 23, 24.
1979. Glycymeris mifunensis Tashiro; Matsukuma, Venus (Japan. Jour. Malac.),vol. 38, no. 2, p. 11I.
1982. Glycymeris (Pseudoveletuceta) mifunensis Tashiro; Tashiro and Kozai,
Palaeont. Soc. Japan, Sp. Pap., no. 25(in press).

Material :-KSG 3116, KSG 3117 and403

752. Cretaceous bivalves from the Monobe Area
KSG 3121, internal moulds; KSG 3115 andKSG 3118, left valves; all the specimens
are collected from loco 2.

Measurements (in mm.):
Specimen
Length Height Thickness
KSG 3115, L.
8.0
7.2
3.0
valve
KSG 3116, R.
19.4
15.8
in. mould
KSG 3117, L.
12.8
11.8
in. mould
KSG 3121, L.
12.5
in. mould
KSG 3118, L.
13.5
4.1
16.0
valve
Remarks:-This species is characterized
by its narrow hinge plate with small
taxodont teeth and somewhat prosogyrate
umbo. Generally it is rounded in theimmature stage, but is somewhat expanded
to posterior in outline and the nearlysmooth surface except for very fineradial threads on the disk in the mature
stage. The outline is, however, variablefor glycymerids.
Occurrence :-Common at loco 2.

Remarks :-Only one specimen, KSG
3155, ca. 6.3 mm long, ca. 5.8 mm highand 1.7 mm thick, was collected from loco
2. This is probably conspecific with
Septiler milunensis Tamura (1976), from
the Mifune Group of Central Kyushu,
judging from its nearly the same features.
It has, however, somewhat less numerous
radial ribs on the surface than the holotype from the Mifune Group.
Occurrence :-Very rare at loco 2.

Order Pterioida
Suborder Pteriina
Superfamily Pectinacea Rafinesque
Family Entoliidae Korobkov
Genus Entolium Meek, 1865

Entolium sp. d. Entolium
obovatum (Stoliczka)
Plate 65, Figs. 6 and 7
1928. Pecten

Order Mytiloida
Superfamily Mytilacea Rafinesque(Syncyclonema)

cf.

obovatus

Stoliczka; Yabe and Nagao, Sci. Rep.
Tohoku Imp. Univ., ser. 2, vol. 9, no.
3, p. 87, pI. 17, figs. 3-6.
1938. Pecten

Family Mytilidae Rafinesque(Syncyclonema) aff. obovatus
Jour. Fac. Sci.,
Hokkaido Imp. Univ., ser. 4, vol. 4,

Stoliczka; Nagao,

Subfamily Mytilinae Rafinesquenos. 1-2, p. 128, pI. 16, figs. 1, 2.

Genus Septiler Recluz, 1848

1975. Entolium sp. cf. E. obovatum (Stoliczka) ;Hayami, Univ. Mus. Univ. Tokyo, Bull.

Septiler d. milunensis Tamura
Plate 63, Fig. 7
Compare.1976. Septifer mifunensis Tamura, Mem. Fac.
Educ. Kumamoto Univ., no. 25, nat.

sci., pp. 54, 55, pI. 2, figs. 1-18.
1982. Septifer cf. mifunensis Tamura; Tashiro
and Kozai, Palaeont. Soc. Japan, Sp.
Pap., no. 25 (in presg).

no. 10, p. 73.
1975. Entolium sp. cf. E. obovatum (Stoliczka) ;Tamura, Mem. Fac. Educ. Kumamoto
Univ., no. 24, nat. sci., pI. 3, fig. 9.
1981. Entolium sp. cf. E. obovatum (Stoliczka) ;Hayami and Kase, Trans. Proc. Palaeont.
Soc. Japan, n. s., no. 121, p. 34, pI. 4,

fig. 7.

Material :-KSG 3156, internal mould ofright valve, from loco 2; KSG 3157, external mould of left valve, from loco 2.

404

Masayuki TASHIRO and Tomoko MATSUDA

Measurements (in mm.):
Specimen
KSG 3156, R. in. mould
KSG 3157, L. ex. mould

Length Height
16.0
9.7
12.4

Remarks:-The hinge structure is wellpreserved in KSG 3156. A pair of cardinal crulae is horizontal, situated underthe beak, elongated with about a third of
the valve length. A trigonal resilifer islarge for the genus. The specimens fromthe Fukigoshi Formation somewhat differ
from Pecten (Syncycionema) obovatus
Stoliczka (1871, pi. 32, figs. 6-9) from
India, in its large ears and long hingeline.
Occurrence :-Common at loco 2 andloco 3.

Family Pectinidae Rafinesque
Subfamily Chlamydinae Korobkov
Genus Nippononectes Tashiro, 1982
Nippononectes kozaii Tashiro
Plate 63, Figs. 1-6
1982. Nippononectes kozaii Tashiro, Mem.
Fac. Sci. Kochi Univ., ser. E, vol. 3,(in press).

Material :-(see, Tashiro, 1982).
Remarks :-This species is characterized
by the strong radial ribs on the surface
and large ears for Nippononectes.
Occurrence :-Common at loco 2 andloco 3.

Family Propeamussiidae Abbot
Genus Parvamussium Sacco, 1897
Parvamussium cowperi yubarense(Yabe et Nagao)

1928. Pecten (Propeamussium) cowperi var.
yubarensis Yabe et Nagao, Sci. Rep.
Tohoku Imp. Univ., ser. 2, vol. 9, no.
3, p. 88, pI. 16, figs. 17-19.
1932. Pecten (Propeamussium) cowperi var.
yubarensis Yabe et Nagao; Nagao,
jour. Fac. Sci. Hokkaido Imp. Univ.,
ser. 4, vol. 1, no. 1, p. 38, pI. 6, figs.
7, 8, 12, 13.
1956. Pecten (Propeamussium) cowperi var.
yubarensis Yabe et Nagao; Amano,
Kumamoto jour. Sci., ser. B, sec. 1, vol.
2, no. 1, p. 73, pI. 1, fig. 12.
1975. Propeamussium cowperi yubarense (Yabeet Nagao) ; Hayami, Univ. Mus. Univ.
Tokyo, Bull. no. 10, pp. 82, 83.
1976. Parvamussium cowperi yubarensis (Yabeet Nagao); Tashiro, Palaeont. Soc.
japan, Sp. Pap. no. 19, p. 52, pI. 4,
figs. 20-24.
1982. Parvamussium cowperi yubarense (Yabeet Nagao); Tashiro and Kozai, Ibid.
no. 25 (in press).

Material :-KSG 3220, internal mould ofleft valve, from loco 3; KSG 3221,
external mould of imperfect right valve,from loco 1.
Remarks :-A specimen, KSG 3220, 9.0
mm long and 8.9 mm high, is characterizedby 8 inner radial ribs. The secondary
inner ribs are not observable in it.
Another specimen from loco 1 is anexternal mould of imperfect right valve,
which is characterized by numerous weakradial ribs. The ribs are composed ofprimary and secondary elements. This
species undoubtedly conspecific with
Pervamussium cowperi yubarense (Yabe et
Nagao), from the Upper Cretaceous ofJapan (see, Tashiro, 1976), because of its
inner and outer ornamentations and its
rounded outline. This species is discriminated from Parvamussium kimurai(Hayami), from the Lower Cretaceous ofAridagawa and Monobe areas (Hayami,
1965; Tashiro et aI, 1980), and Parvamussium hinagense Tamura (1973), from

752. Cretaceous bivalves from the Monobe Area
the Lower Cretaceous of Hinagu, by
having less develop secondary inner ribs
and weaker radial ribs on the disk. This
species is discriminated from Parvamussium
sp. from the Maastrichtian formation of
the Himenoura Group of Amakusa-Shimojima, Kyushu (Tashiro and Otsuka, 1980),
by its distinct radial ribs on the surface.
Occurrence :-Rare at loco 1;' common
at loco 3.
Superfamily Anomiacea Rafinesque
Family Anomiidae RafinesqueGenus Anomia Linne, 1758
Anomia sp. aff. Anomia foldia Tamura
Plate 65, Figs. 1-5
Compare.1977. Anomia foldia Tamura, Mem. Fac. Educ.
Kumamoto Univ., no. 26, nat. sci., pp.
110-111, pI. 1, figs. 8-22.

Material :-KSG 3158 and KSG 3159,
left valves and KSG 3222, right internalmould, from loco 2.
Measurements (in mm.):
Specimen
KSG 3158, L.
valve
KSG 3159, L.
valve

Length Height Thickness
29.8

28.1

10.3

25.4

21.8

10.3

Remarks:-The shell is very inflated inleft valve but nearly flat in right valve,roundly ovate in outline. The test israther thick. Regarding those characters,
the specimens from the Fukigoshi Formation are very close to Anomia foldia
Tamura (1977), from the Mifune Groupof Central Kyushu. They are, however,somewhat smaller than Anomia foldia.
Occurrence :-Common at loco 2.

Suborder Ostreina

405

Superfamily Ostracea Rafinesque
Family Ostreidae Rafinesque
Subfamily Ostreinae RafinesqueGenus Crassostrea Sacco, 1897
Crassostrea kawauchidensis Tamura
Plate 63, Figs. 8, 9, 11
1938. Ostrea sp. (sp. nov.), Matsumoto, Jour.
Geol. Soc. Japan, vol. 45, no. 532, p.
13, text-figs. 1, 2.
1977. Crassostrea kawauchidensis Tamura,Mem. Fac. Educ. Kumamoto Univ., no.
26, nat. sci., p. 114, pI. 2, figs. 1-5.
1982. Crassostrea cf. kawauchidensis Tamura;Tashiro and Kozai, Palaeont. Soc. Japan,
Sp. Pap. no. 25 (in press).

Material :-KSG 3166, internal mould ofleft valve from loco 2.
Remarks :-Though many specimens
occur from this locality (loc. 2), they
are imperfect or fragmentary except fora specimen, KSG 3166. The KSG 3166
is measuerd 46.8 mm in length, 118.7 mm
in height and 33.5 mm in thickness. The
test is very thick. This specimen iscertainly identified with Crassostrea kawauchz'densis Tamura (1977), from the Mifune
Group of Central Kyushu, because itshows the same specific diagnosis.
Occurrence :-Abundant at loco 2.

Order Trigonioida
Superfamily Trigoniacea Lamarck
Family Trigoniidae Lamarck
Subfamily Pterotrigoniinae van Hoepen
Genus Pterotrigonia van Hoepen, 1929
Subgenus Scabrotrigonia
Dietrich, 1933

406

Masayuki TASHIRO and Tomoko MATSUDA
Pterotrigonia (? Scabrotrigonia)
imanishii (Nakano)
Plate 64, Figs. 1-6, 8, Text-fig. 71956. Trigonia
Pocilli/ormis
Yokoyama;
Imanishi, Kumamoto Jour. Sci., ser. B,
vol. 2, no. 1, p. 53, figs. 1-3.
1958. Scabrotrigonia imanishii Nakano, Jour.
Sci. Hiroshima Univ., ser. C., vol. 2,
no. 2, p. 230, pI. 29, figs. 1-4.
1975. Pterotrigonia (Scabrotrigonia) imanishii(Nakano); Hayami, Univ. Mus. Univ.
Tokyo Bull., no. 10, p. 120.

Material :-KSG 3214, external mould ofright valve; KSG 3181-KSG 3212, externalmoulds of left valves; KSG 3211, rightvalve; all the specimens are collectedfrom loco 3.
Description :-Shell medium to small insize, crescentric in outline, longer thanhigh, moderately inflated; umbo prominent
but not so large, strongly opisthogyrous,
located at about a fourth or fifth fromfront of the valve; anterior margin
convex, gradually changing into broadly
arched ventral margin; ventral marginelongated, nearly straight or slightly
sinuated on the posterior half; siphonal
margin well rounded, strongly expanded
to posterior; posterior dorsal margin
long, concave; disk ornamented withroof-shaped and finely tuberculated costae;
6 or more costae near umbo sub concentric,
finely crenulated; next 7 or so costae
strong, situated diagonally on the mainpart of the disk; later 5 or more costae
short, subradial on the posterior part ofthe disk; area broad with a distinct
median groove, ornamented with 6 ormore divaricated costellae each of which
consists of a sub horizontal costella on thedorsal side of the median groove and an
oblique costella on the posterior carinalside of the groove; the divaricated costellae
finely tuberculated narrower than theirinters paces but strongly impressed;

escutcheon rather broad with 10 or moretransverse tuberculated costellae, strongly
depressed; posterior carina not angulated
except for near umbo; dorsal carina
rather indistinct.
Measurements (in mm.):
Specimen
KSG 3181, L.
ex. mould
KSG 3211, R.
valve
KSG 3212, L.
ex. mould
KSG 3214, R.
ex. mould

Length Height Thickness
28.2

21. 7

25.9

25.9

9.4

21. 9 ca 13.4
16.0

13.0

Observation :-This species is characterized by the divaricated costellae on thearea and finely crenulated costae on theumbonal part of the disk. The area isvery narrow in young stage (about 25 mm
in length), but soon rapidly broadenedwith growth in later stages. The growthlines on the area are very weak. Several
subconcentric costellae are indistinctly discernible on the area near the umbo. The
apical angle is about 60· or less.
Comparison :-This species is undoubtedly conspecific with Scabrotrigonia imanishii Nakano (1958), from the Horombetsu
Formation (Imanishi, 1956) of northern
Hokkaido, judging from the same specificdiagnosis which is well defined by Nakano(1958). Scabrotrigonia was established by
Dietrich (1933) as a distinct genus of
Trigoniidae, based on Trigonia scabra
Lamarck, from the Upper Cretaceous ofEurope. Cox (1969) ranked Scabrotrigonia
down to a subgenus of Pterotrigonia van
Hoepen (1929). This species is clearly
distinguishable from the type species of
Scabrotrigonia (op. cit.) in its transverse
costellae on the escutcheon and thedistinctly angulated posterior carina whichis gradually changing into well elevatedrounded ridge in the later stage. So far
as we can see, it is questionable whether
this species belongs to Scabrotrigonia or752.

Cretaceous bivalves j1"Orn the Monobe A1"ea407

Pt erotrigonia ( ? Scabrotrigonia)
monobeana Tashiroet Kozai
Pl a te 64, Figs . 7, 11 - 14, 18-21 ;P la te 65, F igs. 18- 19

1982. Pterotrigonia (Scabrotrigonia ) monobea71a T as hiro e t Koza i, Pala eon!. Soc .
japan Sp . Pa p., no. 25 (in press) .

Pt ero tr igonia (? Scabro trigo nia) imanishii (Na kano)Text-fig. 7.

to a new subgenus of Pt erot rigonia.
This species differs clear ly fromPt erot rigonia(Scab rot rigonia). obsoleta(Nakano), from the Goshonoura Group(Nakano, 1958; Tamura, 1978), in its
distinct divaricated costellae which aredeveloped on the entire surface of thearea and weak growth lines of the area.
This is discriminated from Pterotrigonia(Scabrotrigonia) kobayashii (Nakano), from
the Mikasa Formation of Hokkaido(Nakano, 1958; Tamura, 1978), by having
its strong divaricated costellae on thearea and distinctly crenulated costae on
the umbonal part of the disk.
This species is simi lar to Pt erotrigonia(Jlcanthotrigonia) pustulosa (Nakano), fromthe Goshonoura Group of Centr al Kyushu(Nagao, 1930; Tamura, 1978), in thefeatures of costae and costellae on thedisk and escutcheon, but differs in its
distinct di varicated costellae on the area.

Pt erotrigonia (Jlcanthotrigonia) moriana(Yehara), from the Hag ino Format ion of
Kochi Prefecture (Yehara, 1927; Koba yashi and Nakano, 1957), also resembles thisspecies, but is discrimin ated by its numerous obliq ue costellae on the ar ea.
Occurrence :- Abundant at loco 3.

Mat erial :- KSG 3185- KSG 3189, imperfect external moulds of right va lves;
KSG 3180- KSG 3183, externa l moulds ofleft valves; all the specim ens collectedfrom loco 2.
J\I/easurement s (in ml11. ) :Spec imen
KSG 3180, L.
ex . mould
KSG 3183, L.
ex. mould
KSG 3189, R.
ex. mould

Len gth He ig ht Thickness

44.8

22.1

21. 9

14. 3

5. 5

15.0

12.0

3.0

Remarhs :- Many
specimens
wereobtained from the Fukigoshi Formation.
This species is characterized by thenarrow but lon g area w hich is strong ly
expanded to the posterior, the Haidaialike finel y crenu lated costae on the disknear the umbo, and 5 or more distinct
oblique costell ae on the area near theumbo. The ornamentation of the area inthis spec ies are quite variable. On some
spec imens the coste ll ae on the area arecharacterized by fin ely pustulated a nd
chevron-shaped costell ae as in Pl erotrigonia( ? Scabrotrigonia)
imanishii (Nakano).
The chevron-shaped costellae are, however, very low and weaker than those of
P. (? S. ) imanishii. In severa l specim ens,
the area is nearly smooth except forinciistinctl y di scernibl e chevron-shaped
costellae in t he early stage. This spec ies
is akin to Pterolrigonia (Jlcanthotrigonia )yeharai (Nakano et Numano), from the408

Masayuki TASHIRO and Tomoko MATSUDA

Goshonoura Group in Kyushu (Nakano
and Numano, 1961; Tamura et al., 1968),
in its smooth area and finely crenulated
umbonal costae, 'but is discriminated byits small shell and numerous costae on
the disk.
Occurrence :-Abundant at loco 2.

costae on the disk and the semicircularoutline of the valve.
Occurrence :-Rare at loco 2.
Subclass Heterodonta
Order Veneroida
Superfamily Lucinacea Fleming

Subgenus Acanthotrigonia
van Hoepen, 1929

Pterotrigonia (? Acanthotrigonia)
mashikensis (Tamura et Tashiro)
Plate 64, Figs. 9, 10
1967. Acanthotrigonia mashikensis Tamura et
Til-shiro, Mem. Fac. Educ. Kumamoto
Univ., no. 15, nat. seL, p. 19, text-fig.
2, pI. 1, figs. 1-7.
1975. Pterotrigonia (Acanthotrigonia) mashikensis (Tamura et Tashiro); Hayami,
Univ. Mus., Univ. Tokyo, Bull. no. 10,
p. 120.
1977. Pterotrigonia (Acanthotrigonia) mashikensis (Tamura et Tashiro); Tamura
Mem. Fac. Educ. Kumamoto Univ., no.
26, nat. sci., p. 116, pI. 4, figs. 1-8.
1982. Pterotrigonia (Acanthotrigonia) mashikensis (Tamura et Tashiro); Tashiro
and Kozai, Palaeont. Soc. Japan, Sp.
Pap. no. 25 (in press).

Material :-KSG 3182, external mould ofleft valve, from loco 2.
Remarks :-KSG 3182 is measured 30.9mm in length, 18.1 mm in height and10.4 mm in thickness. The specimen issomewhat deformed, but the features ofthe external surface are well preserved.
This species is characterized by the finecrenulations of the anterior margin nearumbo, striated costellae on the escutcheon,nearly smooth area except for several
loosely spaced oblique costellae nearumbo, less numerous smooth and low

Family Lucinidae Fleming
Subfamily Myrteinae Chavan
Genus Myrtea Turton, 1822

Myrtea (s.l.) sp.
Plate 65, Fig. 23

Material :-KSG 3165, internal mould ofright valve, from loco 2.
Description :-Shell very small, subquadrangular in outline, longer than high,weakly inflated; umbo not prominent,
small, pointed at nearly mid-length of thevalve; anterior margin nearly straight
but weakly concave near umbo; posterior
dorsal margin weakly convex; anterior
margin very weakly arched, truncatedvertically from the dorsal margin; ventral
margin broadly arched; posterior margin
a little convex, truncated subverticallyfrom the dorsal margin; apical angle
about 120·; hinge plate long with two
small cardinals and both lateral teeth;
lateral teeth elongated; anterior adductor
scar oblong, weakly impressed; posterior
adductor scar small; fine and numerous
radial striae appear on the internal surface, extending from the umbonal axis todistinct pallial line; inner margin smooth.
Remarks :-Only one specimen, KSG
3165, 10.4 mm long and 8.7 mm high, isobtained. The external features of thisspecimen is unknown.
Occurrence :-Rare at loco 2.

752.

Cretaceous bivalves from the Monobe Area

Family Mactromyidae Cox

Genus Anthonya Gabb, 1864

Genus Thetis Sower by, 1826

Anthonya sp., cf. Anthonya

Thetis sp. aff. Thetis japonica(Yabe et Nagao)

mifunensis Tamura
Plate 65, Figs. 16, 17

Plate 65, Figs. 20-22
Compare.1928. Thetironia affinis (Whiteaves) var.
japonica Yabe et Nagao, Sci. Rep.
Tohoku Imp. Univ., ser. 2, vol. 9, no.
3, p. 89, pI. 17, figs. 14a, 14b and 15a.
1975. Thetis japonica (Yabe et Nagao);
Hayami, Univ. Mus. Tokyo, Bull. no.
10, p. 122.
1976. Thetis japonica (Yabe et Nagao);
Tamura and Tashiro, Atlas of JapaneseFossils, no. 43-258, pI. Cr.-24, figs. 17,
18.
1981. Thetis japonica (Yabe et Nagao);
Hayami and Kase, Trans. Proc. Palaeont.
Soc. Japan, n. s., no. 121, pp. 37, 38, pI.
5, figs. 2-4.

Material :-KSG 3173 - KSG 3174, left
valves from loco 2.
Measurements (in mm.):
Specimen
KSG 3173, L.
valve
KSG 3174, L.
valve

409

Length Height Thickness
10.2

8.4

3.0

10.5

8.3

4.4

Remarks :-The specimens from the Fukigoshi Formation are somewhat deformed.
Although their hinge structures are unknown, they are probably referable to
Thetis japonica (Yabe et Nagao), fromthe Cenomanian of Japan (Tamura andTashiro, 1976; Hayami and Kase, 1981),
because of the well inflated valve androunded outline.
Occurrence :-Common at loco 2.

Compare.1977. Anthonya mifunensis Tamura, Mem.
Fac. Educ. Kumamoto Univ., no. 26,
nat. sci., pp. 116, 117, pI. 4, figs. 13-19.
?1981. Anthonya sp. cf. A. apicalis Nagao;
Hayami and Kase, Trans. Proc. Palaeont.
Soc. Japan, n. S., no. 121, pp. 38-39, pI.
4, fig. 17.

Material :-KSG 3167b, internal mouldof left valve, from loco 2; KSG 3167a,external mould of the same specimen as
KSG 3167b.
Remarks:-The specimen is measured
about 33.5 mm in length and 10.2 mm inheight. The external surface of thespecimen is ornamented by numerous
concentric striae on the anterior half.
The posterior carinal ridge is moderatelly
inflated. The umbo is located subterminal,
less prominent. The anterior margin of
the valve is more or less protruded toanterior. The apical angle is about 90·.
The hinge formula is as follows:AlII 3a 3b 5b PIlI/AIl 2 4b PIl PIV
Inner buttress is long and nearlyvertical.
This species is possibly con specific with
Anthonya mifunensis Tamura (1977), from
the Mifune Group of Central Kyushu,
judging from the features mentioned
above.
Occurrence :-Rare at loco 2.

Family Mactridae Lamarck
Subfamily Mactrinae Lamarck

Superfamily Crassatellacea

Genus Cymbophora Gabb, 1869

Family Crassatellidae Ferussac? Cymbophora sp.

Masayuki TASHIRO and Tomoko MATSUDA

410

Measurements (in mm.):

Plate 65, Figs. 24-26

Material :-KSG 3175 and KSG 3197,

left valves, from loco 2.
Description :-Shell small, rounded subtriangular, well inflated; umbo orthogyrous, slightly prominent, located at a half
distance from anterior margin; anterior
and posterior margins rounded; ventral
margin broadly arched; anterior andposterior dorsal margins nearly straight;
apical angle about 100·; inner marginsmooth; external surface nearly smooth;lunular area well depressed.
Measurements (in mm.):
Specimen
KSG 3175, L.
valve
KSG 3179, L.
valve

Length Height Thickness
19.0

14.8

3.2

11.8

8.5

2.8

Remarks:-The hinge structures of thisspecimens are not clear. Imperfectcardinal teeth and a small resilifer areslightly observable under the beak.
Occurrence :-Rare at loco 2.

Specimen
KSG 3171, R.
valve
KSG 3172, L.
in. mould

Length Height Thickness
18.2

12.4

13.8

11.8

5.7

Remarks:-These two specimens arereferable to Eomiodon matsubasensis Tamura(1977), from the Mifune Group in Kyushu,
as they show the same diagnosis as
defined by Tamura.
The specimen, KSG 3171, is characterized by 10 concentric ribs, which are
regularly spaced, narrow but distinctly
raised and sometimes finely laminated on
the top. The escutcheon and lunule are
distinct, smooth and well demarcatedfrom the disk. The hinge structures arewell preserved on the specimen, KSG
3172. PII and All are very long on bothsides of the hinge plate. The cardinal 2
is subvertical; 4b is longer than 2 andobliquely situated.
Occurrence :-Rare at loco 2.

Superfamily Veneracea Rafinesque
Family Neomiodontidae Casey

Family Veneridae Rafinesque

Subfamily Eomiodontinae Hayami

Subfamily Pitarinae Stewart

Genus Eomiodon Cox, 1935

Genus Goshoraia Tamura, 1977

Eomiodon matsubasensis Tamura

Goshoraia crenulata (Matsumoto)

Plate 65, Figs. 14, 15

Plate 65, Figs. 12, 13

1938. Astarte sp., Matsumoto, jour. Geol. Soc.
japan, vol. 45, no. 532, p. 16, text·fig.

1938. "Callista" (Pseudamiantis) crenulatus
Matsumoto, jour. Geol. Soc. japan,
vol. 45, no. 532, p. 19, text·figs. 12, 13,
pI. 1, fig. 5.
1956. Pseudamiantis crenulatus (Matsumoto) ;Amano, Kumamoto jour. Sci., ser. B,
sec. 1, vol. 2, no. 1, p. 78, pI. 1, fig.
26, pI. 2, figs. 13-19.
1963. "Callista" (Pseudamiantis) crenulatus
Matsumoto; Iwasaki, Trans. Proc.
Palaeont. Soc. Japan, n. s., no. 51, p.

4.
1977. Eomiodon matsubasensis Tamura, Mem.
Fac. Educ. Kumamoto Uuiv., no. 26,
nat. sci., pp. 127-128, text·figs. 6, 7,
pI. 6, figs. 9-19, pI. 7, figs. 10, I!.

Material :-KSG 3171, right valve, fromloco 2; KSG 3172, internal mould of left
valve, from loco 2.

752. Cretaceous bivalves from the Monobe Area94, pI. 15, figs. 4-7.
1975. Pseudamiantis? crenulata (Matsumoto) ;Hayami,Univ. Mus. Univ. Tokyo, Bull.,no. 10, p. 144.
1977. Goshoraia
crenulata(Matsumoto) ;Tamura, Mem. Fac. Educ. Kumamoto
Univ., no. 26, pp. 139-140, text-fig. 14,
pI. 9, figs. 9-16.
1981. Goshoraia
crenulata(Matsumoto) ;Hayami and Kase, Trans. Proc. Palaeont.
Soc. Japan, n. s., no. 121, pp. 39-40, pI.
5, figs. 5-8.

Material :-KSG 3169, right valve, fromloco 2.
Remarks :-A sole specimen, KSG 3169,
is in our hand, measured 29.0 mm inlength, 28.0 mm in height and 9.9 mm inthickness. It is undoubtedly conspecificwith Goshoraia crenulata (Matsumoto),
from the Goshonoura Group in Kyushu(Matsumoto, 1938; Tamura, 1977), becauseof its sub internal radial ribs and numerous
irregularly concentric striae both on thedisk, . prominent and prosogyrate umbo,
subovate outline and finely crenulated
inner margin.
Occurrence :-Rarely found at loco 2.

Subfamily Tapetinae Adams et Adams
Genus Legumen Conrad, 1858
? Legumen sp.
Plate 65, Figs. 8-10

Material :-KSG 3163, left internal andexternal moulds, from loco 2.
Description :-Shell small, elongately
ovate, weakly inflated; umbo small, notprominent, nearly orthogyrous, pointed alittle anterior than the mid-length of thevalve; anterior and posterior margins
well rounded; ventral margin verybroadly arched; anterior dorsal margin
slightly concave; posterior dorsal margin
nearly straight; surface smooth; posterior

411

carinal ridge weakly elevated but notangulated; lunule indistinct; escutcheon
narrow but elongated, distinctly separated
from the disk by an angulated posterior
dorsal carina; hinge plate very narrow
with two small cardinal teeth; inner
margin smooth.
Remarks :-A specimen, KSG 3163, ismeasured 14.6 mm in length, 6.9 mm inheight and 2.5 mm in thickness. It is
probably referable to the genus Legumen
Conrad (Myra Keen, 1969) in its two
small cardinal teeth without lateral teethon the narrow hinge plate, less inflated
valves and elongated outline.
Occurrence :-Rare at loco 2.
Concluding remarks

The bivalve fauna of the Fukigoshi
Formation which is mainly represented
by the fossils from loco 2, closely resembles
that of the Lower Formation of the Mifune
Group in Central Kyushu, which has been
well defined by Tamura (1976-1979).
There are many common species between
them, i. e., Mesosaccellamifunensis,
Matsumotoa
unisulcata,
Glycymeris(Pseudoveletuceta) d. mifunensis, Septifer
d. mifunensis, Anomia aff. foldia, Crassostrea
kawauchidensis,
Pterotrigonia(? Acanthotrigonia) mashikensis, Eomiodon
matsubasensis and Goshoraia crenulata.
As is concluded by Tamura (1979) on
ample evidence, the fauna of the Lower
Formation of the Mifune Group consistsof the shallow-marine and brackish-waterelements. Its brackish-water elements
are represented by the species belonging
to Eomiodon, Pseudasaphis, Matsumotoa
and Nipponicorbula. The Fukigoshi faunaalso contains Eomiodon matsubasensis andMatsumotoa unisulcata, though rather
rarely. It is, however, of mixed naturein that some offshore elements such as
the species belonging to Acila (Truncacila),

412

Masayuki TASHIRO and Tomoko MATSUDA

Nucula (Pectinucula), Portlandia (s.l.),
Nippononectes and Parvamussium, areassembled with the near shore shallowmarine elements, e. g., the species of
Anthonya, Anomia, Crassostrea, Glycymeris,

Nanonavis, Septifer, Goshoraia
andPterotrigonia.
The fauna of the Fukigoshi Formation
is distinguished from the fauna of the
Middle Formation of the Goshonoura

Explanation of Plate 62
Acila (Truncacila) monobensis, sp. nov.
Fig. 1: lateral view of right valve (KSG 3101), x 1.5, loco 2.
Fig. 2: lateral view of right valve, gum cast of external mould (KSG 3102), x 1.5, loco 2.
Fig. 3: lateral view of imperfect right valve, gum cast of external mould (KSG 3103),
x 1.5; loco 2.
Fig. 4: lateral view of left valve, gum cast of external mould (KSG 3114b) , x 2, loco 2.
Fig. 5: anterior view of imperfect right valve, gum cast of external mould, x 2, loco 2.
Fig. 6: posterior view of imperfect right valve, gum cast of external mould, x 1.5, loco 2.
Fig. 8: lateral view of right internal mould (KSG 3109), x 1.5, loco 2.
Fig. 9: lateral view of right valve, gum cast of external mould (KSG 3107), x 1.5, loco 2.
Fig. 10: lateral view of right internal mould (KSG 3110), x 1.5, loco 2.
Nucula (Pectinucula) kochiensis, sp. nov.
Fig. 7: lateral view of right internal mould (KSG 3113), x 1.5, loco 2.
Fig. 11: lateral view of right valve, gum cast of external mould (KSG 3111), x 1.5, loco 2.
Fig. 12: lateral view of left internal mould, x 1.5, loco 2.
Fig. 13: lateral view of right valve, gum cast of external mould (KSG 3114), x 2.5, loco 2.
Fig. 14: lateral view of right valve, gum cast of external mould (KSG 3112), x 2, loco 2.
Fig. 15: lateral view of right internal mould (same specimen with KSG 3112), x 2.
Nanonavis pseudocarinata, n. sp.
Fig. 16: inner lateral view of right valve, gum cast of internal mould (KSG 3162), x2,
loco 2.
Fig. 17: lateral view of right internal mould (same specimen with KSG 3162), x 1.5.
Fig. 18: lateral view of right valve (same specimen with KSG 3162), x 1.5.
Mesosaccella mifunensis Tamura
Fig. 19: lateral view of right valve (KSG 3122), x 2, loco 2.
Fig. 20: lateral view of right valve (KSG 3123), x 2, loco 2.
Fig. 21: lateral view of right internal mould (KSG 3127), x 2, loco 2.
Fig. 22: lateral view of left internal mould (KSG 3125), x 2, loco 2.
Portlandia (s.l.) nagaseana, sp. nov.
Fig. 23: lateral view of right internal mould (KSG 3132), x 1.5, loco 2.
Fig. 24: lateral view of right internal mould (KSG 3133), x 2, loco 2.
Fig. 25: lateral view of imperfect right valve (KSG 3132), x 1.5, loco 2.
Glycymeris (Pseudoveletuceta) d. mifunensis Tashiro
Fig. 26: lateral view of right internal mould (KSG 3116), x 1.5, loco 2.
Fig. 27: lateral view of left valve, x 1.5, loco 2.
Fig. 28: lateral view of left internal mould (KSG 3121), x 1.5, loco 2.
Fig. 29: lateral view of left valve, gum cast of external mould x 2, loco 2.
Matsumotoa unisulcata (Amano)
Fig. 30: lateral view of right valve, x2, loco 2.
Fig. 31: lateral view of left valve, gum cast of external mould (KSG 3149), x 2, loco 2.
Fig. 32: lateral view of left internal mould (KSG 3148), x 2, loco 2.

TASH i RO and MATSUDA:

Cretaceous bivalves

Plate 62

11

2

3

....

~.

12

6

5
4

9

10
13

7
16

14

17

18

15

8

19

21

28

24

27

29

30

31

752. Cretaceous bivalves from the Monobe Area
Group in Kyushu (Matsumoto, 1938 ;Matsumoto and Tashiro, 1975), in theabsence of such species as Pterotrigonia(? Acanthotrigonia) ogawai (Yehara), P.
(? A.) dilapsa (Yehara), P. (? A.) pustulosa,P. (? Scabrotrigonia) obsoleta, Nipponitrigonia aff. kikuchiana (Yehara), Anthonya
japonica Matsumoto, Crassatella nagaoi
Matsumoto and Glycymaris (Hanaia) solida
Nagao, which are very common in the
Goshonoura fauna. It shows, however,some similarity to the fauna of the upper
part of the Middle Formation of the
Goshonoura Group of the Shishijima
Island (upper part of IIe Member by
Yamamoto and Hayami, 1971), by theoccurrence of Nanonavis pseudocarinata,
Eonavicula sp., Matsumotoa unisulcata,
Nucula (Pectinucula)kochiensis andParvamussium cowperi yubarense. Thisis probably due to the situation that the
Goshonoura Group itself has facies-changes
even at the same stratigraphic level.
The geological age of the fossiliferous
bed (locs. 1-3) of the Upper Member of
the Fukigoshi Formation is not determined
precisely, because no leading fossil has
been obtained. It is probably referable
to the lower Lower Cenomanian, judging
from the following lines of evidence:1: Most of the bivalve species from the
Fukigoshi Formation are hitheto
well known in the Cenomanian strata
in Japan.
2: The Nagase Formation, which ischaracterized by the occurrence ofLower Cenomanian ammonites, e. g.,
Mantelliceras japonica Matsumoto(1982), covers conformably the topof the Fukigoshi Formation.
Anagaudryceras sacya (Forbes), whichranges from the Albian to Cenomanian,occurs in the Lower Member of the
Fukigoshi Formation (Matsumoto, 1982),
but any species of Graysonites whichindicates the lowest Cenomanian, has not413

yet been found from this formation.
Although where abouts of the boundary
between Albian and Cenomanian is still
uncertain, it is probably allocated in thelower part than the fossiliferous bed of
the Upper Member.
In connection with the age of the Fukigoshi Formation, the Horonbetsu Formation of northern Hokkaido (Imanishi,1956) is also determinable tentatively to
the Lower Cenomanian or neaby age on
the evidence of a common species,
Pterotrigonia (? Scabrotrz"gonia) imanishii(Nakano) which occurs characteristicallynot only in the Fukigoshi Formation but
also in the Horonbetsu Formation.
References
Amano, M. (1965): Some Upper Cretaceous
fossils from Southwestern Japan (part 1).
Kumamoto Jour. Sci., sec. 1, (geol.), vol.
1, no. 1, pp. 63-86, pis. 1-2.
(1957): The Lower Cretaceous faunafrom Hagino in Southern Shikoku, Japan.
Ibid., vol. 1, no. 2, pp. 77-i21, pis. 1-2.
Cox, L. R. (1969): Family Trigoniidae, inTreatise on Invertebrate Paleontology.
Moore ed., Pt. N, Mollusca 6, vol. 1, pp.
N471-N489.
Das Muster red
Dietrich, W. O. (1933):
Gattung Trigonia (Moll. Lam.). Sitzungsberg, Ges. natur/. Freande Berlin, pp.
326-332.
Hayami, 1. (1965): Lower Cretaceous marine
pelecypods of Japan. Mem. Fac. Sci.
Kyushu Univ., ser. D, geol. pt. 2, vol.
15, no. 2, pp. 231-349, pis. 27-52.
(1975): A systematic survey of the
Mesozoic bivalvia from Japan, Univ. Mus.
Univ. Tokyo, Bull., no. 10, pp. 1-249, 10
pis.
and Kase, T. (1981):
Cenomanianmolluscs in a sandstone block from thesea bottom off the southern coast of Kuji,
Northeast Japan. Trans. Proc. Palaeont.
Soc. Japan, n.s., no. 121, pp. 29-50, pis. 4,5.
and Oji, T. (1980): Early Cretaceous

414

Masayuki TASHIRO and Tomoko MATSUDA

bivalvia from the Choshi District, Chiba
Prefecture, japan. Trans. Proc. Palaeont.
Soc. japan, n. s., no. 120, pp.419-448, pis.
51-53.
Ichikawa, K. and Maeda, Y. (1958): Late
Cretaceous pelecypods from the Izumi
Group, Part 2, Orders Taxodontida,
Prionodontida, Dysodotida, Desmodontida
and Adapedontida. jour. Inst. Poly tech.
Osaka City Univ., ser. G., pp. 71-122, pis.
3-7.
Imanishi, S. (1956): On the occurrence ofTrigonia bearing sandstone at Horombetsu,
Utanobori·mura,
Esashi-gun,
North
Hokkaido. Kumamoto jour. Sci., ser. E,
no. 1, pp. 49-55.
Iwasaki, Y. (1963) : Pseudamiantis, a pelecypod
genus. Trans. Proc. Palaeont. Soc. japan,
n. s., no. 51, pp. 91-101, pis. 14, 15.
Katto, j. and Suyari, K. (1956): Geology ofMonobegawa basin in Shikoku. Res. Rep.
Kochi Univ., vol. 5, no. 23, pp. 1-11.
Kobayashi, T. and Nakano, M. (1957): On
the Pterotrigoniae. japan. jour. Geol.
Geogr., vol. 28, no. 4, pp. 219-238, pis.
16, 17.
Matsukuma, A. (1979): Glycymeridid bivalvesfrom japan and adjacent areas-I. Alpha-betical list of the species allocated to the
Family Glycymerididae. Venus (Japan
jour. Malac.), vol. 38, no. 2, pp. 95-128.
Matsumoto, T. (1938): Preliminary notes onsome of the more important fossils among
the Gosyonoura fauna. jour. Geol. Soc.
japan, vol. 45, no. 532, pp. 13-26, pis. 1-2.
- - (1982) : Ammonites from the Upper
Cretaceous of the Monobe area, Shikoku.
Palaeont. Soc. japan, Sp. Pap., no. 25(in press).
- - and Tashiro, M. (1975): A record of
Mortoniceras (Cretaceous ammonite) from
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Palaeont. Soc. Japan, n. s., no. 100, pp.
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- - and - - (1982): Concluding remarks on
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no. 25 (in press).
Myra Keen, A. (1969): Superfamily Veneracea,
in Treatise on Invertebrate Paleontology.
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N670-N690.
On some Cretaceous
Nagao, T. (1930):
fossils from the island of Amakusa,
Kyushu, japan. jour. Fac. Sci. Hokkaido

Explanation of Plate 63
Nippononectes kozaii, Tashiro
Fig. 1: lateral view of left internal mould (KSG 3150), xl, loc. 2.
Fig. 2: lateral view of left valve, gum cast of external mould of the same specimen (KSG3150).
Fig. 3: gum cast of imperfect internal mould, showing hinge structure and byssal ctenolia,
x 1.2, loc. 2.
Fig. 4: gum cast of imperfect external mould, showing ornamentation on the anterior ear,x 1.2, loc. 2.
Fig. 5: lateral view of left valve, gum cast of external mould (KSG 2993), x 1.5, loc. 3.
Fig. 6: gum cast of imperfect external mould (left valve), x 2, loc. 2.
Septifer d. mifunensis Tamura
Fig. 7: lateral view of imperfect right valve (KSG 3155), x 4, loco 2.
Crassostrea kawauchidensis Tamura
Fig. 8: lateral view of right valves, x 1, loco M-22 (by Tashiro and Kozai, 1982).
Fig. 9: lateral view of left internal mould (KSG 3166), xl, loco 2.
Fig. 11: immature stage of right valve, xl, loco 2.
Nanonavis pseudocarinata, sp. nov.
Fig. 10: lateral view of left valve, gum cast of external mould (KSG 3217), xl, loc.
Sannosawa, Ikushunbetsu, Mikasa City, Hokkaido.

T ASH I RO and MATSUDA.'

Cretaceous bivalves

Plate 6:3

3

5
4

6

2

10

11

752.

Cretaceous bivalves from the Monobe Area

Imp. Univ., ser. 4, vol. 1, no. 1, pp. 125, 3 pis.
- - (1932): Some Cretaceous mollusca fromJapanese Saghalien and Hokkaido (Lamellibranchiata and Gastropoda). Ibid., vol.
2, no. 1, pp. 23-50, pis. 5-8.
- - (1938): Some molluscan fossils from theCretaceous deposits of Hokkaido andJapanese SaghaIien, Part 1, LameIIibranchiata and Scaphopoda. Ibid., vol. 4, no.
2, pp. 117-142, pis. 14-16.
Nakano, M. (1958): Scabrotrigonia in Japan.
Jour. Sci. Hiroshima Univ., ser. C, vol.
2, no. 3, pp. 227-233, pI. 29.
- - and Numano, K. (1961): On some
Gyliakian Pterotrigonia from Kyushu andHokkaido, Japan. Trans. Proc. Palaeont.
Soc. Japan, n. s., no. 43, pp.89-98, pI. 13.
Quenstedt, W. (1930): Die Anpassung an die
grabende Lebensweise in der Geschichte
der Solenomyiden und Nuculaceen. Ceol.
Palaeont. Abh., N. F., bd. 18, heft. 1, pp.
1-119, 3 pis.
Schenck, H. G. (1936): Nuculid bivalves of
the genus Acila. Ceol. Soc. America, Sp.
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StoIiczka, F. (1871): Cretaceous fauna ofSouthern India.
vol. 3, Pelecypoda,
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Lower Cretaceous
stratigraphy in Southern Arizona. Ceol.
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Tamura, M. (1973): Two new species ofLower Cretaceous Parvamussium from
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Ceol. Pal. Southeast Asia, pp. 119-124,
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- - (1975): On the bivalve faunas from the
Gyliakian of Japan. Mem. Fac. Educ.
Kumamoto Univ., no. 24, sec. 1, pp. 5962, pI. 3.
- - (1976-1979): Cenomanian bivalves from
the Mifune Group, Japan. Ibid., Pt. 1:
vol. 25, pp. 45-59, pis. 1-3 (1976); Pt. 2:
vol. 26, pp. 107-144, pis. 1-3 (1977); Pt.
3: vol. 28, pp. 59-74, pis. 1-3 (1979).
- - and Tashiro, M. (1967): Cretaceous
trigoniids from the Mifune Group, Ibid.,
vol. 15, pp. 13-23, pI. 1.

415- - and - - (1976): Mesozoic bivalves ofJapan. Atlas of Japanese fossils, no. 43258.
- - , - - and Motojima, T. (1968): The
correlation of the Mifune Group with theUpper Formation of the Goshonoura
Group, with description of some important pelecypods from the strata. Mem.
Fac. Educ. Kumamoto Univ., vol. 16, sec.
I, pp. 28-42, pI. 1.
Tashiro, M. (1971): Upper Cretaceous glycymerids in Japan. Trans. Proc. Palaeont.
Soc. Japan, n. s., no. 84, pp. 225-242, pis.
27, 28.
- - (1976): Bivalve faunas of the Cretaceous
Himenoura Group in Kyushu. Palaeont.
Soc. Japan, Sp. Pap. no. 19, pp. 1-102, 12pis.
- - (1982): A new pectinid genus Nippononectes from the Cretaceous of Japan.
Mem. Fac. Sci. Kochi Univ., vol. 3, pp.
1-6, pis. 1-2.
- - and Kozai, T. (1982): Bivalve fossils
from the Upper Cretaceous of the Monobe
area, Shikoku. Palaeont. Soc. Japan. Sp.
Pap., no. 25 (in press).
- - , Matsuda, T., Kozai, T. and Katto, J.
(1981): On the Fukigoshi Formation(new name) of the Monobe area, Kochi
Prefecture, Japan. Res. Rep. Kochi Univ.,
vol. 30, nat. sci., pp. 31-42.
- , Okamura, M. and Katto, J. (1980): A
biostratigraphical study of the Lower
Cretaceous formations of Monobe area,
Kochi Prefecture, Japan. Ceology andPaleontology of the Shimanto Belt. Taira,A. and Tashiro, M. eds., Rinyakosaikai
Kochi press, pp. 71-82, pis. 10-11.
- - and Otsuka, M. (1980): Bivalve fossils
from the Uppermost Formation of theUpper Himenoura Subgroup in AmakusaShimojima island, Kyushu. Mem. Fac.
Sci. Kochi Univ., ser. E, Ceol., vol. I,
pp. 41-57, 4 pis.
- - and Yamamoto, K. (1980): On thespecies of Japanese" Nanonavis" (Cretaceous bivalvia) and their biostratigraphicalranges. Res. Rep. Kochi Univ., vol. 29,
pp. 1-12, pI. 1.
Van Hoepen, E. C. N. (1929): Die Krytofauna

416

Masayuki TASHIRO and Tomoko MATSUDA

van Soeloeland, 1, Trigoniidae. Pal.
Navorsing Nas. Bloemfontein, vol. 1, pt.
1, pp. 1-38, pis. 1-7.
Woods, H. (1899-1903): A monograph of theCretaceous Lamellibranchia of England.
vol. 1, xliii+227 p., 42 pis.
Yabe, H. and Nagao, T. (1928): Cretaceous
fossils from Hokkaido; Annelida, Gastro·
poda and Lamellibranchiata. Sci. Rep.
Tohoku Imp. Univ., ser. 2, vol. 9, no. 9,
pp. 77-96, pis. 16, 17.
- - , - - and Simizu, S. (1926): Cretaceous

mollusca from the Sanchu graben in the
Kwanto Mountainland, Japan. Ibid., vol.
9, no. 2', pp. 33-76, pis. 12-15.
Yamamoto, S. and Hayami, 1. (1971): Cre·taceous system of Shishijima, Kagoshima
Prefecture. Sci. Repts., Dept. Ceol.,
Kyushu Univ., vol. 11, no. 1, pp. 35-44.
Yehara, S. (1927): Faunal and stratigraphicalstudy of the Sakawa basin, Shikoku.
Japan. Jour. Ceol. Ceogr., vol. 5, nos. 12, pp. 1-40, pis. 1-5.

Explanation of Plate 64
Pterotrigonia (? Scabrotrigonia) imanishii (Nakano)Fig. 1: lateral view of imperfect right valve, gum cast of external mould (KSG 3211),x 1.5, loc. 3.
Fig. 2: lateral view of right valve (KSG 3211), xl, loc. 3.
Fig. 3: lateral view of left valve, x 1.5, loc. 3.
Fig. 4: lateral view of left valve, gum cast of external mould (KSG 3212), x 1.2, loc. 3.
Fig. 5: lateral view of left valve, gum cast of external mould (KSG 3181), x 1.2, loc. 3.
Fig. 6: gum cast of imperfect left external mould, showing ornamentation of the area, xl,
loc. 3.
Fig. 7: dorsal view of the immature stage of left valve, gum cast of external mould, x 2,
loc.3.
Fig. 8: lateral view of right valve, gum cast of external mould (KSG 3214), x 2, loc. 3.
Pterotrigonia (? Acanthotrigonia) mashikensis (Tamura et Tashiro)
Fig. 9: lateral view of left valve, gum cast of external mould (KSG 3182), x 1.5, loc. 2.
Fig. 10: dorsal view of the same specimen, gum cast of external mould, x 1.5.
Pterotrigonia (? Scabrotrigonia) monobeana Tashiro et Kozai
Fig. 11: posterior dorsal view of imperfect left valve, gum cast of external mould, showing
the ornamentation of the area, x 2, loc. 2.
Fig. 12: posterior dorsal view of left valve, gum cast of external mould (KSG 3183), xl,
loc. 2.
Fig. 13: posterior dorsal view of right valve, gum cast of external mould (KSG 3185),
x 1.2, loc. 2.
Fig. 14: lateral view of immature right valve, gum cast of external mould (KSG 3189),
x2, loc. 2.
Fig. 18: lateral view of left valve, gum cast of external mould (KSG 3180), x 1.5, loc. 2.
Fig. 19: lateral view of left internal mould of the same specimen, x 1.5.
Fig. 20: posterior dorsal view of the same specimen, gum cast of external mould, x 1.5.
Fig. 21: lateral view of left internal mould (KSG 3184), x 2, loc. 2.
Nanonavis pseudocarinata, sp. nov.
Fig. 15: lateral view of left valve, gum cast of external mould (KSG 3202), x 1.2, loco 3.
Fig. 16: lateral view of left internal mould (KSG 3143), xl, loco 2.
Fig. 17: lateral view of left internal mould (KSG 3145), x 1.2, loco 2.
Fig. 23: lateral view of imperfect left valve, gum cast of external mould, x 2, loco 2.
Area (Eo navicula) sp.
Fig. 22: lateral view of left valve, gum cast of external mould (KSG 3161), x 1.5, loc. 2.

TASHIRO and MATSUDA:

Cretaceous bivalves

Plate 64

5

2

7

6

417

752. Cretaceous bivalves from the Monobe Area
Awaji ~~,

Fukigoshi ~if!!,

Goshonoura 1l1lImi'm, Hagino ~!llf, Hegushi ~$,Himenoura1&/ i'm, Horonbetsu *Sj~ZJj, Ikushunbetsu ~~ZJj, Ishido ;fi~, Izumi :fIliR, Mifune 1l1lItd,
Mikasa =:~, Monobe ~$, Nagase 71<mi, Odochi ::kW, Sanchu r.Ll*, Sannosawa =:lR,
Shiroi S:#-, Shishijima _.::r,!1l" Torinosu .!1V ~gg~~~Jli';. ~$!I!!i!i!GO)71<mi!l' A#JlI~:.?t;(ji-tG~if!!J~Ht., r-¥$iJ;7JE!6-~t>-CJ:-¥$iJ;:W)l!6-~t>O)!I!!JI-C;(;Go.:O)J:-¥$.J: I), 4-@]~< O)=tlC~{t;fi~14ko)-C~lIilt-tGo -'ttLi?
ft., Nucula (Pectinucula) kochiensis sp. nov., Acila (Truncacila) monobensis sp. nov.,
Portlandia (s.l.) nagaseana sp. nov., Nanonavis pseudocarinata sp. nov. 0) 4 Wi':fill.~ J"<tr22im24:fill.-C;(;Go .:0)=tlC~0)7 71/:t"ft, :fill.O)f/f$;t:..J: I) Cenomanian O)1:lf;i'fiH~;(;G\"ft.Miiia~~~ 1..- -(I,'G it.::.': 0) 77 1/ :t"ft, :fIJNO)1l1lIltdJlll¥O) 77 1/:t" C ~ <O)~jj:fill.~*t>, Slf-m-t:.ftl"(I,'Go ~if!!JlO)!I!!jt~-R;ft Upper Albian iJ'i? lower Lower Cenomaniancj~XE~tLGiJ;, Albian c Cenomanian O)!1Ejj!.tu::>\"-Cft~ i?t:.~W~Jf-tGo it.::.:<$:JIO)J:$iJ'i?O) Pterotrigonia (1 Scabrotrigonia) imanishii (Nakano) O)jf[I:l::Ht, Im:fill.~jf[-t G~tiia~~t$O)* P :/-" '/ JlO)!I!!jt~-R;HlXE-tG O)t:.]J!Jf-C;(;G
0

0

418

Masayuki TASHIRO and Tomoko MATSUDA

Explanation of Plate 65
Anomia sp. aff. Anomia foldia Tamura
Fig. 1: lateral view of left valve (KSG 3158), x 1.2, loco 2.
Fig. 2: dorsal view of the same specimen, x 1.2.
Fig. 3: lateral view of left valve (KSG 3159), x 1.5, loco 2.
Fig. 4: dorsal view of the same specimen, xL
Fig. 5: lateral view of left valve, xI, loco 2.
Entolium sp. d. Entolium obovatum (Stoliczka)
Fig. 6: internal view of right valve, gum cast of internal mould (KSG 3156), x'2, loco 2.
Fig. 7: lateral view of left valve, gum cast of external mould (KSG 3157), x 2, loco 2.
? Legumen sp.
Fig. 8: lateral view of left valve, gum cast of external mould (KSG 3163), x 2, loco 2.
Fig. 9: dorsal view of the same specimen, gum cast of external mould, x 2.
Fig. 10: lateral view of left internal mould, (same specimen with KSG 3163), x 2.
Matsumotoa unisulcata (Amano)
Fig. 11: lateral view of right valve, gum cast of external mould (KSG 3149), x 2, loco 2.
Goshoraia crenulata (Matsumoto)Fig. 12: lateral view of right valve (KSG 3169), xI, loco 2.
Fig. 13: dorsal view of the same specimen, xL
Eomiodon matsubasensis Tamura
Fig. 14: lateral view of right valve (KSG 3171), x 1.5, loco 2.
Fig. 15: internal view of left valve, gum cast of internal mould (KSG 3172), x1.5, loco 2.
Anthonya sp. d. Anthonya mifunensis Tamura
Fig. 16: lateral view of left internal mould (KSG 3167), x 1.2, loco 2.
Fig. 17: external view of the same specimen, gum cast of external mould, xl.
Pterotrigonia (? Scabrotrigonia) monobeana Tashiro et Kozai
Fig. 18: lateral view of left valve, gum cast of external mould (KSG 3183), x 2, loco 2.
Fig. 19: dorsal view of the same gum cast, x2.
Thetis sp., aff. Thetis japonica (Yabe et Nagao)
Fig. 20: lateral view of left valve (KSG 3173), x 1.5, loco 2.
Fig. 21: dorsal view of the same specimen, x 1.5.
Fig. 22: lateral view of left valve (KSG 3174), xl, loco 2.
Myrtea (s.l.) sp.
Fig. 23: internal view of right valve, gum cast of internal mould (KSG 3165), x 2, loco 2.
? Cymbophora sp.
Fig. 24: dorsal view of left valve (KSG 3175), x 1.5, loco 2.
Fig. 25: lateral view of the same specimen, x 1.5.
Fig. 26: lateral view of left valve (KSG 3178), x 1.5, loco 2.

TAS HIR O and MATSUDA:

Cretaceous bivalves

Flate 65

6

1

4

7

2

11

12

8

14

(
13

9

10

23

25

19

20

21

16

22

17

.....~

26

24

419

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Transactions and Proceedings of the PalaeontologicalSociety of Japan
New Series No. 127

September 30, 1982

CONTENTS
TRANSACTIONS747.

NAKANO, Mitsuo and OKAMOTO, Kazuo : A new species Acesta (Plicacesta)

watanabei from the Miocene in Southwest Japan ....... ...... . . . . . . . . . .. 357
748.

NOHARA, Tomohide and NAKASONE, Noriko:Sexual dimorphism of thepaleocopid ostracode genus Manawa from Okinawa-jima .. . .. .. . . . .. . . . . 364
749.

COPPER, Paul, TAZAWA, Jun-ichi, MORI, Kei and KATO, Makato:

750.

BANDO, Yuji and EHIRO, Masayuki:

Atrypa(Devonian Brachiopoda) from Japan .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 368
On some Lower Triassic ammonites fromthe Osawa Formation at Asadanuki, Towa-cho, Tome-gun, Miyagi Prefecture, Northeast Japan ... .. .... . . . . .. . .. ... .. . . ...... . .. . .. . . . ... ... 375
751.

KATO, Makoto : Ma zaphyllum (Rugosa) from the Silurian of Japan... . . ... 386

752. TASHIRO, Masayuki and MATSUDA, Tomoko : The bivalve fossils from theCretaceous Fukigoshi Formation of the Monobe area, Shikoku ......... . 393
PROCEEDINGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 419\\