fJ -lt"' -I;±~~~~.:k· ic.lJ
Transactions and ProceedinJ!s
of thePalaeontological Society of Japan
New ~eric::;

No. ;{(il'alaeontological Society of japan

November 30, 195~1

CONTENTS
TRANSACTIONS
Page

371.

On Two Specie~ of Polymc:;oda from the T.:tori Group in the IlidalVIountainlancl. Central japan. . ........................... Shiro l\1AEL>A

157

On Some Marine Miocene Mollusca from Mie Prefecture, Japan ....... .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Yoshio AHAKI
373.

161

Taxodonta and Isoclonta from the Jura~sic Soma Group in North japan.
Minoru 'LnwRA

168. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Michihiro KAWA?\Uun314. Two New Permian Corals from Yarr.aguchi Prefecture .

375.

Electron-Microscopic Fine St ructurc of Fossil Diatoms. VI.

Stereoscopic

Observation .............................................. Haruo 0Ku:xo

185

PROCEEDINGS ............................................................... .

192

President:
Councillors:

Teiichi KoBAYASHI

K iyoshi AsANo, l:{iuji ENvo (Publication), Seido EN no, Haruyoshi fuJI·

MoTo (Treasurer). Shoshiro liANZAWA, 1\otora IIATAI. lchiro IIAYAsAKA, Kazuo
HuzioKA. Nobuo IKEBE, Jiro l\lAKIYAMA, Tatsm·o MATsUMoTo, 1\lasao l'VIINATO,
Tukio SmKAMA (General Affairs), fuyuji TAKAt (Editor), l:{yuzo ToRIYAMA
Secretary:

Tetsuro IIANAI

A::;::;istant Secretary:

Takeo IcmKAW AAll Connnunical ions relating to this .Journal should be addressed to the
PALAEO.l\TOLOGICAL SOCIETY OF JAPANc;cological Institute. Faculty of Science, Univcrsit~· of Tok~·o. ,);.panTrans. Proc. Pal. Soc. Japan. N. S., No. 36. pp. 157-160, pl. 17, Nov. 30, 1959

:r11. ON TWO SPECIES OF POLYMESODA FROM THE TETORIGROUP IN THE HIDA 1\IOUNTAINLAND. CENTRAL JAPAN
S!-IlRO l\fAEDA
College of Arts and Sciences, Chiba University.

mWrfJ:itl!OYJ·JfXIr'lllfi!E Polymesoda 2 ftll: d!Fr~ I-.'i<.t:tlliJ~:Ill!~il· ':)~Hilt., t~ ~ 2 f<f(I;J: C~1i"C''f!flllf!'lllfil•f,¥fH!.i·* nt:

c. cO)t.;;t' t OYC. :.~1-r;;G~t.,., (Jj:-tt-c~itl!.illlJ:O)t.lJ:~tW

f€:11!!~0'¥-~ll!!fffO)itl!'l't~ftt:: "?~ •'L~&v L 2 f'i!G)4:Jl ~r.;t'lfrf!f\<::. kobayashii t fia~ t.,.
riu

t:.

El:l

Jllj

Ql.l

The Tochio alternation is provided
with a remarkable reddish or greenish
tuffaceous rock facies as is widely known
from the Cretaceous deposits in andaround Japan. l'vloreover. the fauna now
discovered resembles closely to those of
the Ryoseki and Y osh imo formations
which are ascertained to be Eo-Cretaceous in age. Judging from these facts,
it may. be better to assign the alternation to the Eo-Cretaceous rather than
to the,upper Jurassic as generally con·sidered. From the palaeogeogr~phicalpoint of view. the discovery of the Ryoseki element from the Hida mountainland is extraordinarily important, because the so-called Ryoseki fauna washitherto unknown from the inner zoneof southwest Japan except the Yoshimo
area in Yamaguchi Prcf.
Among the non-marine shells obtained
from the Tochio formation the twoforms of Polymesoda which are specifically determined will be described in
the following pages.
Before going to describe, however, thewriter desires to acknowledge his indeb~edness to Prof. T. KonAYASHt of
Lniversity of Tokyo and Dr. K. SczuKJ
ot the Research Institute for Natural
Resou-rces for their constant guidancein the course of this study. He is also

It has already been reported by T.
and S. 0HoT:\ (19-l9) that the
Tetori group of the Kamitakara district.
Hida mountainland. Gifu Prcf .. central
Japan, contains a non-marine molluscan
fauna with some plants. In 1957 thewriter collected newly such fossils as
Polymesoda (Paracm·bicula) sanc/mensis(YAnE and N,,<;,,o), P. ([sodomella) kobayashii MAEDA n. sp., '' Jlrfelanoides" sp.,··Pita" sp. and so forth.
The stratigraphical succession of theTetori group in the central part of the
Hida mountainland is tabulated below:
KA~'"'

AkaiwajTochio alternation of sandstone
subgroup and shale (about 600 m. thick)
Itoshiro
JTaic alternation of sandstone
subgroup 1 and shale (200-500 m. thick)Sugizaki sandstone (150-200 m.
thick)
KuzuryuNumamachi alternation of sandsubgroup stone and shale (150-350 m.
thick)
Tancmura conglomerate(250-500 m. thick)j

In the Kamitakara district the groupdeveloped along the upper reaches of
the Takahara River consists only of the
Tochio alternation, being inserted byfaults into the metamorphic and nonmetamorphic Palaeozoic basement complexes.
Received Nov. 27, 1958: read April 28, 1958.

Iii I

158

Shiro lV!.4ED;lindebted to l\lr. T. HA:o.IADA, a postgraduate student of University of Tok)To,for his kind advice in the field survey.
Description of Species

Family Corbicu J iclae

Adductor scars situated close to theextremities of the laterals and faintly
impressed. Pallial line simple. Innerside of the shell smooth.
jvfeasurements :-4 type specimens
scarcely deformed measure in mm aslisted below

Genus Polymesoda R.-\FI:-oEsQt:E, 18~0
Subgenus Isodmnella KoaAYJ\SIII
and Suzt.:KI, 1939

Polymesoda (lsodomella) lwbayashii
l\-f.o\EDA, n. Sp.
Plate 17, Figures 1-11.

Description :-Shell large in size, t riangular in outline, somewhat longer thanhigh, inequilateral. moderately shortand well round in front, obliquely produced behind. fairly inflated but moreor less impressed in the median portionof the disc; test thick. Postero-dorsal
margin scarcely curved ncar the beak.
fairly long, straightly sloping into theposterior: posterior margin very short,
rapidly bent forward into the ventral
at an acute angle: ventral margin fairly
long, arched, gradually going over into
the well rounded anterior: antero-dorsal
ma·rgin concave, gently arcuated. Umbo
comparatively large, located at a point
about one-fourth across from the anterior extremity, incurved and directed
forward. somewhat elevated above thehinge-margin. Posterior ridge prominent: posterior area impressed, lanceolate. Surface ornamented with concentric growth lines and sometimes withslightly elevated wrinkles. Hinge-plate
rather large: ca!·dinal teeth three on
each valve. middle and anterior cardinalteeth strong: lateral teeth two, smooth:posterior one slightly curved inward,
long, lameller, parallel with the posterodorsal margin : anterior short.

. Numb~~-Lcngth
1 (Left. I
holotype),
2 (Right)'
3 (Left) I
4 (Left)~~--~-

Height

Width

60

4-1

10x2

60
45
34

4()

37
30

1UX2
7x2
5x2

------

Locality and formation:- The bed of
the Kashiwate River, a tributary of the
Takahara River, in Kamitakara-mura.
Yoshiki-gun. Gifu Pre£.: Tochio alternation of sandstone and shale in the i\kaiwa subgroup, the upper division of theTetori group.
Remarh :-The specimens at hand resemble the figures of Polymesoda ![sodomella) shiroiensis (YAn~: and' !\.-\G.-\o)given by H. YABE, T. NAGAO and S.
Sm:-uztJ in 192() from the Cretaceous
deposits in the Sanchu graben of the
Kwanto massif, central japan. and by T.
KoaAY.\SIII and K. SuzuKI in 1939 fromthe Eo-Cretaceous Yoshimo formation in
the inner zone of southwest Japan. butthey are easily distinguishable therefrom by having the beak situated moreanteriorly and by being much larger insize.
This species is also related to P. (!.)
naumanii (N'Eu~IAYR) figured by E. Ku:1\IA:-.:>~ and 1\l. NwMAYR in 1890 and by
H. YAn"· T. NAGAo and S. S11nnzu in
1926. but they differ from each otherin features of the posterior ridge andoutline of the she II. Though P. (l.)
kueichouensis (GHABAu) described in 1923
by A. W. GR,\BM; from the Cretaceous

371.

Polyrnesoda frm1z" the Tetori Groupdeposits of China shows some resemblances to this new species in generalcharacters, the two species do not coincide in ratio of height to length.
The specific name is cleclicatccl to Prof.
Teiichi KoaA nsm who kindly adviced
the \\Titer through the study of thehistorical geology of the jurasso-Crctaceous Tetori group.
Subgenus Pnmcorbicula KonAYASHJ
and SuzuKI, 1939
Polymesoda (Paracorbicu!a) smzclmensis('{ ADE and NAt;.\o)Plate 17, Figures 12-16..
1Y:?6. Corbicula (Veloritina ') sanchuensis YA·
BE and NM;.\o, Sci. Rep., Tolzoku Imp.
Univ., 2d Ser., Vol. 9, pp. 53-54, pl. 12,
figs. 8, Sa, pl. 13, figs. 8-10, 17, 17a.
1939. Corbicu/a sanchue11sis, KonAY.\SHI and
SUZL'Kl./atxm.four. Geo/. Geogr., Vol. 16,.l•los. 3-4. pp. 221-222, pl. H, figs. 10-15.
l!H9. Polymesoda (Paracorbicula) sanclwensis,

SFZt:KI, japan. ]our. Geol. Geogr., Vol.
21. Xos. 1-4, p. 119.
1955. Polymesoda (Paracorbicula) cf. sanclm·
ensis. Y A~L\GIWA, !liNn. Osaka Unit·.,

Liberal Arts and E'duc., No. 3.

Description :-Shell medium in size,
subcircular in outline. nearly as highas long, inequilateral. well rounded in
front, fairly long and well rounded behind, with the maximum convexity
located close to the umbo; test thick.
Postero-dorsal margin more or lessstraight. sloping into the posterior without making any angle: posterior margin
fairly long, feebly truncated, bent forward with an obtuse angle; ventral
margin long. very broadly arched, graduaily going over into the anterior
margin, which is gently curved: anterodorsal margin well rounded.
Umbolarge, located anteriorly, slightly inflated, incurved. directed forward, some-what projected above the hinge-margin.
Surface ornamented with concentric
growth lines. Hinge well deYeloped;
cardinal teeth three on each valve. twoof them usually strong; lateral teeth
curved, crenated ; posterior one longer
than the anterior. Adductor scar lanceolated ovate; posterior one su bovate
in outline, distinctly impressed especially on its inner margin: posterior one
broader than the anterior. Pallial line
deeply sinuated. Inner side of the shellsmooth.
J!easurements :-More or less broken
two specimens selected from the collection measure in mm. as follows::\umberi

1 (Left) I
2 (Right)

LengthHeight

Width

3l
16

32

10x2
4x2

Locality and formation:- The bed of
the Kashiwate River, a tributary of the
Takahara River, Gifu Pref.: Tochio al·
ternation of sandstone and shale.
Remarks :-Several imperfect specimens were found in the collection.
\Vith regard to the covexity and outlineof this species. T. KonAYAslll and K.
SvzcKJ (1939) had stated that minor
points of these features are not thesame in every specimens, though thechange from one to another is gradual.
The specimens at hand resemble mostclosely to YABE and NAG.-\o·s form illustrated in fig. 8 on Pl. 1~ of their report.
but they slightly differ from the formshown by YAnE and N.\GAO as fig. 9 on
Pl. 1:~ in outline of the shell. The present specimens are also allied to Kon.>.·YASHt and SL'ZL'KJ's specimens. but theformer are generall~T thider than thelatter in width. Nevertheless, none of·these minor differences seems to havea value for specific distinction.

160

Shiro MAEDA
References

GRABAU, A. W. (l923a). Cretaceous Fossil~from Shantung. Bull. Geol. Sun•. China,
Fol. 5, No. 2.
GRABAt:, A. W. (1923b), Cretaceous Mollus.:afrom North China_. Bull. Geol. Sun•.
China, Vol. 5, No. 2.
GRABAU, A. W. (1923c), Contribution to the
Fauna of the Kweichow Formation ofCentral China. Bull. Ceo!. Sun•. China.
Vol. 5, No. 2.
KAMEr. T. and OHOTA, S. (1948), On the
Geology in the Vicinity of Kamitakara·maru, Yoshiki-gun, Gifu Pref. (MS).
KAl\IEI. T. (1952), The Stratigraphy of the
Palaeozoic Rocks of the Fukuji Distrit.:t,Southern Part of Hida Mountainland.
four. Shinslm ["nit• .. Vol. 2.
KOUAYASIII, T. (1939), On the Ryoseki
Fauna in the Inner Zone of Japan. (inJapanese). four. Geol. Soc. Tokyo, Vol.
88. No. 45·1.
KOBA Y.\SIII. T. and Sl'Zl'KI, K.
(1937).
Non-Marine Shell of the Jurassic Tetori
Series in· Japan. ]ajxm. jour. Geol. Geogr ..
Vol. 14, Nos. 1-2.

KoBAYASIII, T. and Sl'ZUK!. K. (1939), The
Brackish Wealden Fauna of the Yoshimo
Beds in Prov. Nagato, Japan. Japan. four.
Geol. Geogr., Vol. 16. Nos. 3-4.
1\L-\EDA, S. (1958), Stratigraphy and Geological Structure of the Tetori Group in
the Hida Mountainland. (in Japanese).
four. Geol. Soc. Japan. Vol. 64, l\ro. 755.
KAt'~J.-\1';:"1, E. und Nrw~JAYR, M. (1890).
Zur Geologie und Palaeontoloige \·onJapan. Denkschr. 11Iath. Natur. Classe
1\ais. 1lkad. Wiss .. Bd. 57.
Sczi:Kr, K. and 0YA~IA, K. (19·13), Ueberblickuber die Corbiculiden Ostasiens. Venus,
Vol. 12, Sos. 1-2.
Su:t.I'KI. K. (1919), Developements of theFossil Non-Marine Molluscan Faunas inEastern Asia. fajJWI. four. Geol. Geogr ..
Vol. 21. Nos. 1-4.
YABE, H., NAGAO, T. and Srmuzt·. S. (1926).
Cretaceous Mollusca from the Sancln1
Graben in the Kwanto ::O.Iountainland,
Japan. Sci. Rep. 1'ohoku Imp. Uniz• .. Ser.
2. Vol. 9, No. 2.
Y:\~1.-\GIWA, N. (1955), Cretaceous Mollusca
from the Shima Peninsula. Japan. 1l1em.
Osaka Univ., Liberal Arts and Educ., No. 3.

Explanation of. Plate 17, . AI! th~ illustr~ted . speci~ens are kept in the Institute of Geology, College of Arts andSciences, Ch1ba Unt\·erstty, Chtba. (Lac: Tochio alternation of sandstone and shale in the
Akai~v~ subgr~up. the upper division of the Tetori group, developed in Kamitakara-mura.
Yosl11kt-gun, G1fu Prcf.)·
Pofymesoda (Isodomella) kobayashii i\IAEDA, new species.
Fig. 1. Left· valve, holotype. x 1. 0.
Fig. 2. Umbonal view of holotype. xI. 0.
Fig. 3. Right valve, paratype. x 1. 0.
Fig. 4. Lateral view of the specimen shown in Fig. 3. x 1. 0.
Fig. 5. Internal mould of left valve. paralype. xo. 9.
Fig. 6. Character of lateral teeth of a paratype. x 1. 5.
Fig. 7. Umbonal view of the specimen shown in Fig. 8. XL 0.
Fig. 8. Left valve, paratype. xI. U.
Fig. 9. Right valve, para type. x 1. 0.
Fig. 10. Lateral view of tht~ specimen shown in Fig. 9. X 1. 0.
Fig. 11. Left \'al ve, paratype. X I. 0.
Polymesoda (Paracorbicula) sa11d111ensis (Y.\liE and N,\GAO)
Fig. 12. Lateral view of the specimen shown in Fig. 13. x1.6.
Fig. 13. Internal mould of left valve. x 2. 0.
Fig. 14. Internal mould of right val\·e. x 1. 2.
Fig. 15. Lateral view of the specimen shown in Fig. 14. xl. 2.
Fig. 16. Character of sinus. x 1. ti.

M AEDA :Polymesoda from the Tetori Group

Plate 1 7

Trans. Proc. Palaeont. Soc. Japan, N. S., No. 36, pp. llil-167, pl. 18, ~ov. 30, 1959:{72.

ON SOME MARINE .:VIIOCENE 1VIOLLUSCA FROM

1IIE PREFECTURE, JAPAN*
YOSHIO ARAKI
Geology Department, Faculty of Liberal Arts, l\lie University.:::'.•ll1'it0ifiir!RJ:!:tWr~~U:jj)J~;::-? 1Y'L: ·-:GIM!ft0~f*il1f?11::"?t'"L 5 Wff<Ii · 2 tfr!II.!Nl
1>~Jif(t_,, .13.-?liTI/mltf0~R;::::~.>t'"Ct'Ff0:X~i'fi"?L}{[.
~~ itt*Introduction and Acknowledgements

During my geological studies in thearea surrounding Tsu City, Mie Prefecture. J have been fortunate in obtaining a large collection of fossil molluscs.
some foraminifers and others. Somemolluscs among of them being con-sidered to represent undescribed forms
will be treated in this article. Allof the fossils are now preserved in
the collection of the Geology Department, Faculty of Liberal Arts, .Mie
University. and those treated in thepresent article are from the lsshi group,
whose stratigraphical sequence is shownin Table 1.

Table 1. Stratigraphical sequence of the Isshi group developed in the area
west of Tsu City, Mie Prefecture
Formation names

Yakuoji

General lithological characteristics
1

Alternation of sandstone and siltstone (more or less tuffaceous)intercalating thin tuff in the upper part. alternation of sandstoneand siltstone (more or less of flysch type) and 5-10 meters thickblack siltstone in the 10\H'r part.

Chaya

Massi\·e sandstone intercalating siltstone layers, alternation ofsandstone and siltstone ;,t places.

Kaisekizan

Alternation of sandstone and tuffaceous siltstone intercalating tuff
in the upper part, dark muddy sandstone with sandy siltstone in
the lower part.

Furutaikc

Arkoze sandstone intercalating thin conglomerate beds of gneissand granite. Thin coal scam.

Kongobo

Alternation of conglomerate and sandstone. cobble to boulder size
conglomerate of gneiss and granite in sandstone matrix .
. . - .· .. unconformity and fault.-------J're·Tcrtiary basement of gneiss and granite.
----* Received Dec. 15, 1958; read 1une 6, 1958.
ll) 1

·-

----------

16~

Unfortunately there are no descriptive
works on the fossil marine mollusca
from the lssh i group in l\Iie Prefecture
but K. TAKntoTo (1935) listed the molluscan fossils from the group and ].
YA:<.tAD.>. (1958) reported the molluscan
fossi Is from the Kaisekizan formationin the southern part of the same group.
Therefore, although a full account of thefossil marine molluscs will be given atanother opportunity. it is thought thatthe descriptions of some of the species
considered to be new to science will
faciliate the studies of other molluscan
paleontologists in Japan and also serve
to suggest the kind of fauna occurringfrom the :\liocene deposits in the area
west of Ise Bay, l'vlie Prefecture.
The molluscan fauna from the Tvliocene
series (!sshi group) developed in thearea west of Tsu City comprise a typi·
cal warm water assemblage, a charac·
tcristic feature of the early l\liocene
marine fauna of Japan. This kind of
fauna is widespread. being known from
IIokkaid6 in the north. from where it
ranges southwards to the tip of themain island of Japan. Everywhere
throughout this area, the early l\liocene
molluscan fauna contains warm water
species. although it is evident that the
number of typically subtropical or
warm temperate forms decrease with
the increase in latitude. and vice versa.
The r.liocene series as represented in
the present area is thought to include
only the early ?vliocene in a two-folddivision of the series. It may be correlated with deposits in other areas
containing such molluscs as Glycymeri>
cisslmensis :\lAI..:IYA~L-\, Gl. idensis 1\,,:-;:xo.
Lima yagenensis On;KA, Periploma yolwyamai lVIAK IYA~IA, ]oanisiella meisensis
1\1AKIL\:<.IA, Dosiuia chikuz.enensis N.>.c.Ao.
Soletelliua minomzsis YoKoY.HIA. Turritella s-IJataii Nn~It'HA. besides others, which

also occur in the present area.
Here I wish to thank Professor Kotora
I-lATA! of the Department of Geology.
Faculty of Education. Tohoku University. for his kind advice concerning thepresent work. I also thank Professors
Shoshiro IiANzAwA and Kiyoshi AsA:-.-oof the Institute of Geology and Paleontology. Tohoku University. for theirkindness during my research in that
Institute.
Descriptions of the New Species

Family Mytilidae
Genus A1usculus Roo1~c. 1798
Jl.fuscu!us hataii ARAKI, n. sp.
Plate 18, Figure 1.

DesrriPfion :-Shell rather large. measuring about 40 mm in length, 25 mm inheight and about lll nun in depth of aright valve. Elongate·subquadrate inoutline. dorsal and ventral borders
nearly parallel with one another: anterior and posterior sides rounded. theanoterior more narrowly than the posterior. rather inflated with thin shell.
obscurely provided with fine radial
threads or striae on posterior and anterior sides of shell. the whole withfine concentric growth lines. Beakswollen, inturnecl. directed forwards;
obscure but wide depressed area extending from behind beak to middle toposterior part of ventral margin.
Remarks:- This new species resembles
Musculus laevigatus (GI~AY) ligured by
T. HAHE (1955, pl. 4. figs. 12, 13) from
Hokkaido. but can be distinguishedthe ref rom by the more prominent beak,less flaring posterior side of the shell,
more equally parallel dorsal and ventral
margins. and by the less distinct radialstriae.

37 2. l\1arine Miocene l\1ollusca from Mie Prefecture
Locality and Keological formation:Roadside cliff at about 300 meters
northwest of Onohira, Gein6-ch6. Agegun. I'vlie Prefecture. Kaisekizan formation, Miocene.
Depository :-Geology Department, l\lie
University.

Family Periplomatidae
Genus Pe1·ip/oma ScHt':.I,\CIIER, 1817
Perip/oma mitsuganoense
ARAI<I, n. sp.
Plate 18, Figures 2a. 2b.

DescriPtion :-Shell moderate in size.
rather long, more or less rounded, subquadrate in outline. inequivalve, theright deeper and better preserved thanthe left: anterior and posterior borders
rounded. the latter more broadly than
the former; ventral border broadly
rounded. rather sharply passing into
anterior one but gradually into the posterior: beaks small. pointed, directed
anteriorly. umbonal region slightlr
swollen: anterior dorsal border narrowly
rounded angulation: surface provided
with periodic undulating and interstitial
finer concentric growth lines. of whichthose of the latter arc obscure: illdefined blunt ridge extending from infront of beak towards antero-ventral
corner, becoming obscure near midregion. Length about 43 mm, heightabout 34 mm. depth of intact valves
about 10.5 mm.
Remarks :-This species has been compared with Perip!oma besslioense (YoKoY.\MA) (YoKOYAl\IA, 1924), P. yokoyamai
lVL\I:IY.-\:1-IA (MAKIYAMA, 1934), P. pu/che/fum HATAI and NtsiYAMA (HATM and
NisiY.·\:'>tA, 19·!9), P. ovata Kl·RoDA andHoRIEOSIII (1\t;RoDA and HoR!I<Oslll, 1952).

16:3

and P. o/o/z.imeae HAI3E (IlAnE, 1952), andwas found to differ from each of thementioned ones by the size of the shell.
outline. angularity of the anterior halfof the shell. and by the growth lines
being periodically undulating and having obscure interstitial ones.
Besides the holotype specimen there
are several paratypes. but the majority
are more or less fractured or deformed.
but still retain the specific charactersabove described.
Locality and geological formatimz :Tsuzumi Pass. Mitsugano, 1-:!akusan-cho.
Isshi-gun, Mie Prefecture (J-Iolotype andPara types). Cliff of the sou! hern slope ofKaisekizan, Sakakihara. Hisai-cho, lsshigun, Mie Prefecture (Paratypes). Hothof the Kaisekizan formation. Miocene.
Depository :-Geology Department, Mie
Uni\·ersity.
Family Carclitidae
Genus Venericardia LA:~.JAJ~ci<, 1801
Venericardia funayamrnsis
ARAKI, n. sp.
Plate 18. Figure 3.

Drsrription :-Shell rather large. measuring 4fi.5 mm in length, 42 mm inheight and about 16 mm in depth of aright valve. Subquadrate in outline.
longer than high, moderately convex;
beak small, pointed, directed forward,
umbonal region not much swollen ; postero-dorsal border long. rather straight,
and forming with broadly roundedventral border a rather sharp but
rounded angulation: antero-dorsal siderounded. gradually merging into ventral
border with large angulation. Surface
with about 22 radial ribs, which aremuch broader than their narrow valleylike interspaces; radial ribs broadly

] ()4

Yoshio ARAKI

rounded, sharply descending into narrowv-shaped interspaces, crossed with concentric growth lines: eroded shell surface with radial ribs as squarely rounded elevations about equal to or a little
narrower than their fiat-bottomed interspaces. Hinge-teeth and other internalfeatures inaccessible.
Remarks:-This new species is easily
distinguished from Venericardia siogamensis Nm.lt:IL\ (1935. pl. 17, figs. 8-11),
a Miocene species originally describedfrom Siogama City, Miyagi Prefecture.
by the shape of the shell which is more
trigonal: the number and type of radialribs in the two species are about thesame, but the size and shape of theshell are quite different.
Locality and geological formation:Road cutting on road leading from
Funayama to Kozahara. l\lisato-mura,Age-gun, \lie Prefecture. Kaisckizan
formation. Miocene.
I >eposit01y: --Geo I ogy Department. l\1 ie
University.

Remarks:-This new species resembles
Cyclina (Cycli11orbis) lrmulata MAEIYAMA(1926, pl. 13. fig. 1) from the i\liocene ofNorth Korea, but may be distinguishedtherefrom by the more expanded anterior side. weaker concentric sculpture,
more arched antero-dorsal border andless straight posterior border. Cyclina
japonica KA:o-.rADA (1952, pl. 15, figs. lab, 2, 4) from the ivliocene of Gifu Prefecture, differs from the present one by
the shape of the shell.
The specific name is gi\·en in honor of
Mr. Yasuhiko KM.rADA of the Nagasaki
University, who had particular interestin the species of the genus Cyclina.
Lorality and geological formation:Small cliff at the paddy-field situatedat about 200 meters northwest of Bessho,
Misato-mura. Age-gun, l\Iie Prefecture.
Furutaike sandstone. Miocene.
Depository :-Geology Department. Mie
University.

Family Veneridae

Family Dentaliidae

Genus Cyclina DEsHAYEs, 1849

Genus Dentalium Lrl'\Kt~, 1758

Cyclina kmnadae ARAJ,J, n. sp.

Dentaliwn misatoeusis
ARAKI, n. sp.

Plate 18, Figures 4a, -lb.

Description :-Shell large in size, alittle longer than high, subcircular.
Antero-dorsal border broadly expanded.
the riostero-dorsal roundly sloping into
posterior side which is well rounded.
Anterior side rounded, well expanded.
Ventral margin rather sharply roundedwith fine crenulat'ions on its innerborder. Shell rather thin, provided withfine concentric growth lines and periodic
coarse ones. Beak small, pointed, incurved, directed anteriorly. Sinus andmuscular impressions obscured. Height50.5 mm, length about 53.5 mm, depth ofa right valve about 15 mm.

Plate 18, Figures 5a, 5b.

Description :-Shell generally large,
measuring more than 75 mm in lengthand exceeding 9 mm i:1 diameter, test
heavy. Shell nearly straight, only
slightly curved, gently tapering. Apertural and apical extremities broken.
Smooth throughout. only with \\·eakconcentric growth rings. Shell of undersurface with undulating rings.
Remarks:-This species more or lessresembles Dentalium- 1ceinkauffi Dv-.KER
figured by HrRASE (1932, pl. 3, fig.), a372. Marine ivfiocene Mollusca from Mie Prefecturecommon Recent shell of japan and also
occurring as fossil from the Pliocene toyounger deposits of Japan. However,in Du;-.;KJm's species there are longitudinal striae at the apical part, whereas
they are not developed in the present
new species, and the shell of the present specimens is thicher.
This is a common species in the present area where it occurs in association
with many other molluscs of the genera
Venericardia, Turritella. Euspira andencrusting calcareous algae.
Locality and geological formation:Road cutting on road leading from
Funayama to K6zahara. Funayama, l\lisato-mura, Age-gun. lVIie Prefecture(Holotype).
Roadside cliff at thewestern side of Nakamura. Hisai-cho,lsshi-gun, Mie Prefecture. Both oi the
Kaisekizan formation. .iVIiocene.
Depository :-Geology Department, l\Iie
University.

165

Remarks :-Unfortunately the featuresof the aperture remain unknown owing
to the covering of the matrix and also
the youngest whorls could not be extracted from the matrix ..
Locality and geological formation:-Small cliff near the temple of Yanagidani, Misato-mura, Age-gun. Ivlie Prefecture (Holotype). Kaisekizan formation. 200 meters north of Kubo on roadleading from Kubo to Shibukuro in thewestern part of Tsu City. Mie Prefecture. Yaku6ji formation. Both Miocene.
Depository :-Geology Department. I\lie
T..;niversity.

Family Neptuneidae
Genus Ancistrolepis DALL, 1894

Ancistrolepis trodioideus miensis
ARAKI, n. subsp.
Plate 18, Figures 7a, 7b, 8.

Family Volutidae
Genus Fulgoraria Scnn.tAcHER, 1817

Fulgoraria hirasei yanagidrmieusis
ARAKI, n. subsp.
Plate 18. Figure 6.

Description:- The present subspecies
resembles Fu!goraria hirasei SowERRY
figured by Sl'.tiTH (1942. pl. 10. fig. 78)
in general features, but can be distinguished therefrom by the narrowershell, more twisted canal, more narrowly
spaced longitudinal ridges which extend
nearly over the body whorl as mere
striations, and by the concentric striae
being apparently stronger. The curvatuni of the shoulder is more expanded.
Height about 71 mm, maximum diameter of body whorl about 18 mm.

Description:- This new subspecies resembles Ancistrolepis troclzoideus DALL
(1921, pl. 9, fig. 5: SuzuKI, 1935) ingeneral shape of the shell and in thepossession of spiral cords which aremuch narrower than their interspaces
and which often contain one or two
intercalary threads. However. the present one differs from DALL's species inhaving eight spiral cords on the bodywhorl. three in the adult on the penultimate and in young specimens only twoon the penultimate and one on thesecond whorls. The whorls are lessshouldered. more rounded. and the spiralcords rarely accompany with intercalarythreads. Height 40 and 22mm. maximum
diameters of body whorl 26 and 16 mm
respectively for two specimens (Cotype).
Remarks :-Neptunea onmrai OTUK A(1940, pl. 11, figs. 5, 6) from the Miocene

16(1Yoshio AR.tKI

deposits in Teshio Province. IIokkaido.
more or less resembles the present sub·species, but can be distinguished fromit by the narrower and higher shell.
less recurved canal, and by the number
and strength of both spiral cords andintercalary threads.
Locality and geological formation:200 meters north of Kubo on road leading from Kubo to Shibukuro in thewestern part ,of Tsu City. Mie Prefec·
ture. Yaku6ji formation. Cliff of thesouthern slope of Kaisekizan. Sakakihara,
Hisai-cho, Isshi-gun, Mie Prefecture.
Kaisekizan formation. Both Miocene.
Deposi!Oty :-Geology Department. lVIie
University.

Literature Cited\V. H. (1921). Summary of the Marine
Shellbearing Mollusks of the Northwest
Coast of America from San Diego, Cali·
fornia, to the Polar Sea. mostly Con·
tained in the Collection of the UnitedStates ::\ational Museum, with Illustra·tions of Hitherto Unfigured Species.
Bull. U.S. Nat. Mus., 110. 112, 217pp .. 22
pls.
IIABE. T. (1952), Genera of Japanese Shells.
Pelecypoda, no. 3, pp. 186-278 (refer to
pp. 264-265, text-tigs. 700, 701)
(1955), Fauna of Akkeshi Bay.
XXI. Pelecypoda and Scaphopoda. Pub/.
Akkeshi Mar. Bioi. Stat .. 110. 4, pp. 1-31,
7 pls.
HATAI. K. and S. NrSIYA~I:\. (1949), New
Tertiary l\Iollusca from Japan. ]our.
DAJ.L.

Explanation of Plate 18(All figures in natural size)

1lfusculus hataii ARAKI. n. sp. Holotype. Loc.: Roadside cliff at about 300 meters
northwest of Onohi ra, Gein6-ch6, Age-gun. Mie Prefecture. Kaisekizan formation.
Figs. 2a, 2b. Periploma mitsuganoense ARAKI, n. sp. Ilolotype. Loc.: Tsuzumi Pass. Mitsugano.
Hakusan·cho, Isshi-gun, l'..Iic Prefecture. Kaisekizan formation. 2a. view of theright valve. 2b. view from the dorsal border.
Fig. 3. Veuericardia fmwyamcnsis ARAEI. n. sp. I-Iolotype. View of the right valve. Loc.:
Road cutting on road leading from Funayama to Kozahara. Misato-mura, Age-gun.
Mie Prefecture. Kaisekizan formation.
Figs. 4a, 4b. Cyclina kamadae ARAKI, n. sp. Holotype. 4a, view of right valve. 4b. view ofthe same from the beak. Loc.: Small cliff at the paddy-field situated at about 200
meters northwest of Bessho, Misato-mura. Age-gun. Mie Prefecture. Furutaikesandstone.
Figs. 5a. 5b. Denta!ium misatoensis ARAKI, n. sp. Holotypc. 5a, lateral view. 5b. cross section of the aperture. Loc.: Road cutting on road leading from Funayama to Koza·
hara, ?v1isato-mura. Age-gun, Mie Prefecture. Kaisekizan formation.
Fig. 6. Fulgoraria hirasci yanagidanien,,is ARAKI. n. subsp. Holotype. Although the apicalpart is not fully exposed, the characters are of subspecific value. Loc.: Small cliff
ncar the temple of Yanagidani, Misato-mura, Age-gun, Mie Prefecture. Kaisekizan
formation.
Figs. 7a, 7b. 8. Ancistrolepis trochoideus mieusis i\RAKI. n. subsp. Cotype. 7a. back view of
7b, which is the front view. 8. fractured specimen showing the features of theyounger whorls. Loc.: Cliff of the southern slope of Kaisekizan, Sakakihara, Hisai·cho, lsshi·gun, lVlie Prefecture. Kaisekizan formation.
Fig. 1.

ARAru : Miocene Mollusca from Mie
Plate 1 8
2a

8

7a

2b

4b

5b

lCuMA«Ar Photo,372.

Marine Miocene lV!oltusca fronz Mie Prefecture

Pat.. rot. 23, no. 1, pp. 87-94. 2 pis.
HIR:\SE, S. (1931).
Scaphopod Mollusks
found in Japan. ]our. Conch., vol. 19, no.
5. pp. 132-141. 17 figs., 1 pl.
KA~L·\DA, Y. (1952).
On Some Species of
Cyclina from Japan and Korea. Trans.
Proc. Palaeont. Soc. japan. N. S., 110. 6, pp.
167-173. 1 pl.
Kt;RoD ..\. T. and M. HoRIKOSlll. (1952), On
Two ;..[ew Species, Perip/oma Ol'a/a and0_1}'adesma nakamigawai (Periplomatinae).
japan. jour. Malac., z·ol. 17, no. 1, pp. Hi22, 3 figs.
MAEIYA~tA.]. (1926). Tertiary Fossils from
North Kankyo-do. Korea. Mem. Colt. Sci ..
Kyoto Imp. Unit• .. Ser. B. 1·o/. 2. 110. 3, art.
8, pp. 143-160. 2 pls.
- - - (1943). The Asagaian Mollu::;ca of
Yotukura and Matchgar.
1\Jem. Colt.
Sci .. 1\yoto Imp. Unil• .. Ser. JJ, l!O/. 10,
no. 2. art. 6, pp. 121-167. 5 pis.
r\n~IL'RA. S. (1935).
Miocene Mollusca from
Siogama. Northeast Honsyu, Japan. Saito
Ho-on Kai l11us .. Res. Bull.. no. 6, pp. 193234. 2 pis.

161

On:K,\. Y. (1940). Miocene Mollusca from
Te::;io Province. Hokkaido. Japan. ]our.
Geol. Geog1·.. ml. 17, nos. 1-2, pp. 91-99.
1 pl.
S~liTil. M. (194:!).
A Review of the Volutidae.
Beai-Maltbie Shell },Jus. Pub!.. 70 pp., .26
pis.
Suzt:Kl, K. (1935). On the Fossil .4llcistrole·
pis trochoideus (0.\LL) from the Pliocene
Formations of Boso Peninsula. ] apw1.
four. Malac., vol. 5, no. 4, pp. 187-194, 9 figs.
TAKllllOTo. K. (1935). On the Cenozoic System in the Environs of Isshi-gun. Mie
Prefecture. Chikyu, vol. 23. no. 5, pp.
326-338. 1 map.
Y,\~IADA, J. (1958), On the Geology of the
Tertiary Formation in the Drainage ofthe Kumozu River. with Reference theIsshi Group. fub. Pub!. Commen. Prof.
ll. Fujimoto's Sixtieth Birthday. pp. 277281, 1 map. 3 figs.
YoKoYA\1:\, M. (1924). Molluscan Remains
from the Lowest Part of the Joban Coal·
Field. ]our. Coil. Sci .. Imp. Uni1:. Tokyo.
ml. -15. art. 3, pp. 1-22. 5 pis.

Trans. Proc. Palacont. Soc. Japan. N. S., No. 36, pp. 168-180, pl. 19, Nov. 30, 1959

:37:3.

TAXODONTA AND ISODONTA FROM THE JURASSICSOJ\IA GROUP IN NORTH JAPAN*
1\IINORU TAMURA
Faculty of Education, Kumamoto University·~AMffi~w~-~~5~®D8=tt~reE:
miWJf!!lHf1<:A.;!1.fdl.o!f10l1VJa,~,J'ilJFI30~1~0

lsodonta (15 flli,

3 t> 3 ~ft]) "i>~~i\l~Jt~om~~~5~MW8=ttRreEw~t.M

3 t 2 ~f!!D &0:
L.;!'\.i;.0::".[:l{J!l.1tt:i1iimtii!!£JII:ttl!15&0:1tHi
Taxodonta (6 :j)H.

t 0 c fttif!:1 VC:b I). L. ;f1, t? 3 :lti!~O)!IiJJf~ilf0ti!ilif:l:~~VCP ;J.,
X ':!til§ «X &0: t:" 7 '1' • .:c. =r ;;t t:'-1' I.K CD l:$ ~ .::L 5 'b·; i!fi -9.;:, Ctenostreon probo-

0~;;-fi:jlf;ji[(O)~m*fei!fi0*

scideum (J. So\Y.) 'b;i!fiU:Ii' 7.>,It has long been known that the
Koike limestone in Soma district. f'ukushima Prefecture (Province of Iwaki) isa member of the Jurassic Torinosu
limestone widely distributed along the
Pacific side of Japan. It was referred
to Kimmeridgian by KoB.\YASIII (1935)
by AulacosPfzinctoides aff. steigeri. According to MAsATA;-o;I (1950) the Soma
Jurassic \~vhich forms an anticlinolium
consists of the following formations indescending order:
Koyamada formation- - - conformity
Tomi:r.awa formation- - - conformity.:-;akanosawa formation- - - conformity
Tochikubo formation- - - fault (probably unconformity)
Sugaya formation- - - disconformity
Awazu formation- - - unconformity
llayama formation

Giving fossil lists by provisional de-* R"ceived Jan. 17, 1959: read Ft.:b 14,
1959.

168

lfl

ff

~

termination. 1\IL\SATANI suggests Bathonian or Callovian, Oxfordian or Kimmeridgian and Portlandian respectively
for the Awazu, Nakanosawa and Koyamada formations. Subsequently KnicRA(1954) studied the sedimentary rocks of
the Nakanosawa formation with theresult it was found that the Koike
limestone is not a single bed but anaggregate of limestone lenses with marlyand sandy intercalations.
Because the group contains several
fossil beds and its structure is relatively simple, it bears special importancefor the Upper Jurassic stratigraphy in
1he Pacific side of Japan. Under theguidance of Prof. T. KoBAYASHI, thewriter has studied the group and discovered 10 zones of Trigoniae (Fig. 2).
as already described by T. Ko!L\YASIII
and the writer (1956, 1957). Judging
from the Trigoniae. the Soma Jurassic
can be divided into two major parts.
namely, the upper or the KoyamadaNakanosawa formations and the lower
or Sugaya-Awazu formations. In theupper, 111yop/wrella. especially Haidaia,
is the leading members. Haidaia. in373.

Taxodonta and 1sodonta jrom tlze Jurassic Soma Groupparticular, is restricted to this partand its equivalents in West Japan. On
the other hand, the lower Trigonian
assemblage characterized by Scap/wlrigonia. Latilrigonia and lbotrigonia issimilar to the Aratozaki assemblage andthe lower Tetori assemblage. l\7ipponilrigonia sagau:ai, however, occurs fromthe lower as well as the upper part.
Its occurrence is also reported from theTorinosu and Tetori groups. ?\o pelecypod species is common between the
Sugaya and Nakanosawa formations, although there are some co-existent genera.

16!1

The present study is dealt \vith thepelecypods from the Nakanosawa andKoyamada formations.
Beside the Trigoniae Neoburmesia iwakieusis was described by YABE and SATO
(1942) and SomaPecten kamimanensis andAequiPeclen ogmcensis by Kr~tt:RA (1951 ).
Here the Taxodonta and Isodonta aredescribed. The stratigraphic notes. fos·sil zones and localities are summarized
and shown in figures 1-4 and table 1.
The fossils. here used. were collectedby iVIAsATAKI, KIMURA and others including the writer and stored in the
Geological Institute. University of Tokyo.
The writer wishes to express his cordial
thanks to Prof. T. Kos.>. YAsur of the
University of Tokyo for constant guidance, supervision of the manuscript andpermission for describing the fossils in
his institute. Thanks are also due toAssist. Prof. T. Kr!\tuRA. ~Iessrs I. HAYA ~~~ and A. ToKtJYA:-.rA of the same
university for their assistances.
Family Parallelodontidae
Genus Paralldodon MEEK and\VORTIIE:'\,

1866

Parallelodou Jwikensis TAMCRA,
new species
Plate HI, Figures 9-11.

Fig. 1. Fossil localities of Koyamada
and Nakanosawa formations.
H: Hayama
J: Jisahara
K: Kurumagawa
Ki: Koike
Ky: Koyamada
M: Minahara
0: Oyama
T: Tomizawa
To: Tochikubo

Y: Yamashita
Jlf: Minamisawa.Ua: l\Iano riYer
N: Nakanosawa
Ta: Tatenosawa
U: Umasawa
Y: Yasukirasawa
1-16: sec Table 1.

Description :-Shell small, moderately
inflated. much inequilateral. elongate
and rectangular in outline, about twice
as long as high; umbo slightly incurved.
at about 1/3 from anterior end; dorsal
margin subparallel to ventral: umbonal
furrow shallow but causing a sinuation
on ventral margin: umbonal carina distinct; post-carina! area strongly depressed; radial ribs numerous, fine but
strengthened on lateral sides, especiallyso about post carinal 8.

Mi1wru, TAMURA

110

u

10
t

8

7

Tc

:(-~;~_':·(.',}\\·?
r•,r!': • • ·.' : ·.: • .' ',•:_

Ko

q

p

m

9 '"·.. ·...... ......................

Fig. 2. Pelecypod's
fossil zones in Soma ] urassic group ( x 1/1250)

Fig. 3. Nakanosawa
formation at Nakanosawa (XI/125)

Aw: Awazu formation
Ha: Hayama formation
Ko: Koyamada formation
Na: l\:akanosawa formation
Su: Sugaya formation
Tc: Tochikubo formation
Tm: Tomizawa formation
1-10: Trigonian zones
a: coarse ss
b: Lima rich ss

I

Fig. 4. Koyamada
formation at Umasawa(X I/125)c: platy ss
d. c. g, h: coarse quartzose ss
f : calcareous ss
i : calcareous Is bearing ss
j: Koike Is, bearing sandy & marly partk. m. p, r, t : black sh partly sandy sh
I. o: coarse ss
q. s. u: black sh. partly sandy ss and richin onion structure37 3.

Taxodonta and Isodonta from the jurassic Soma Group
Table 1.

No. of Fossil I No. of Trigonian
locality inzones in Fig,. 3
Fig. 1
1

2
3
·I

5
6
7
8

)\akanosawa, Tomizawa, Soma city

7

Minamisawa, Tomi.zawa. Soma city

II

7
5 & 6
8

10
11

10

12

9
8
8
7 & 8

13

14
15
16

Fossil locality

6
5

7
5
10
10

9

171

Fossil locality and its horizon

II

North yalley of Ilayama, Kamimano·villagc, Soma co.
East of Minahara, Kamimano·village. Soma co.
West of Yamashita (Yasukurasawa), Kamimano·village.
South of Yamashita, Karnimano·village.
' V{est of Kurumagawa, Karnimano·village.
Umasawa, Koyamada. Kamimano·village.
/1

Koike, Kamimano·\'illage.
Tatenosawa. Koike, Kamimano·village.

6

II

Table 2.

Fossil spedes and its range chart
Fossil Zone

Fossil species
5Para/lelodon lwikensis T:\:-tt:RA. n. sp.
Parattelodon aff. injlatus TA:-tLRA
Grammatodon takiensis Kl~lt:!L\
Grammatodmz (bulogrammatodon) densistriatus T.\:\JURA. n. sp.
Catella (Torinosucatella) kobayashii TA:>.JlJRA
Nuculana (Dacryomya) stenodoliclzos K; :-.n R A
Chlamys camptonecloides T ..nJt'R.\, tl. sp.
Clzlamys sp.
Chlamys (Radulopecten) ogmcensis (Kt ~~ t K ..-.)
Camptonet:les sp.
"Aequipectelt'' zmlgaris Kl:>.ll'RA"A.equipec!etz" kotsubu Kl:O.ICR A
Eopecten pzmctus (KI~HJR,\)
1;1tlo/ium yatsujie1zse Kt:R:\TA and K1~JLRA
Entolimn llimurai TA~IURA
Somapecten kamimanensis Kl:O.IUR.'\
Lima (Ctenoides) tosana Kt:>.JL'RA
Lima (P/agiostoma) enorn:icosla TA:>.JUL\. n. sp.
Lima (Plagiostoma) sp.
Ctenoslreon proboscideum (]. SowERBY)
P!icalula dichotomocosla T,\\ll'!{:\, n. sp.

6

7

8

X

X

X

X

X

X

9

10

X
X
'

X

X

X

X
X

X

X
X

X

X

X
X
X
X

X
X
X

X

X

X
X
X
X
X

------

)
1 .....
I~

Minoru TAM UR.l
1lleasurements :-LHllolotype (left valve: MM3193)

21 mm

Paratype (left valve: MM3195)

20

10 111111
10

Obserl'alion :-Two left valves and an
incomplete right valve at hand areblack. probably stained by carbonaceous
matter which is rich in the Koike limestone. The furrow on surface is shallow
but distinct in the paratype specimen(l\IM3195). The elongate shape and fairly
coarse ribs on the depressed post-carina!
part are the characteristic of the species.
It is a non-alate Parallelodon.
Comparison:- This can b!! easily distinguished from P. injlatus TA.\WRA(1959) in its small size. anterior umboand elongate outline. P. nimnolzame11sis
H."-'"''""' (1958) from the Liassic Niranohama format ion is quite different fromit in the post-carina! ornaments. Areaquadrisu/mla Sow. (LoRtoL et PELLET:
1875) from the Sequanian of Mont desBoulogne-sur-Mer is somewhat allied toit. but the post-carina! ribs are only 4.
Para!lelodon fw_vserlingii (d 'OruliG:-~Y) fromthe Oxfordian of Cambridgeshire (AR1\ELL; 19~9) resembles it but the postcarina! ribs are not so coarse.
Occurrence :-7th zone at Locs. 13, 15
and 8th zone at Loc. 14.
Parallelodou aff. infiatus TAMVRA
Plate 19, Figures 12-15.
aff. 1959.

Parallelodon injlatus,

TAJ\!l7RA,p.

53. pl. 6, figs 9, 10.

Description :-Shell medium to large,
innated. elongated and somewhat oblongin outline; umbo incurved, improminent:umbonal furrow shallow; ventral marginsinuate at the end of the furrow; umbonal angulation carina-like; surface withnumerous radial ribs and concentric
growth-lines; hinge of Paralle/odon type.
Observation:-This description is founded on a incomplete internal mould andits external one. Its large and inflated
form agrees probably P. injlatus fromthe Jurassic SaKamoto formation. though
the furrow on surface is invisible in
the Sakamoto form. The surface ornaments consist of numerous radial ribs
in addition to a secondary rib in eachinterspace and many concentric lines. It
looks like a net-work.
Occurrenre :-9th zone at l.oc. 1~.
Family Cucullaeidae
Genus Grammalodou MEEK
and HAYDEN, 1.860
Grammatodon takiensis K rM nr~A
Plate 19. Figures 4· 6.

Grammatodon takiensis, Kt~IL:R.\, p. 85,
pl. 1. fig. 6.
1959. Grammatodo11 takie11sis, TA:O.!VR:\, p. 54,
pl. 6. figs. 1, 2.
1956.

This species is variable in outline andornaments but generally small. Radial
ornaments are feeble or obsolete in the
middle part. Anterior radial ribs areusually about 13 but posterior ones varyin number. In some, 3-4 secondary ribs
are inserted but in others primary andsecondary ribs are indistinguishable.
Occurrence :-5th zone at Locs. 7, 8:
7th zone at Locs. 13, 15; 8th zone at
Loc. 14; 9th and lOth zones at Locs. 9,10, 11, 12.

37 3.

Taxodorzta and Isodont a from the jurassic Soma Group

Subgenus Jndogrammatodon Cox, 1937
Gmmmatodon (Jndogrammatodon)
drmsislriatus T,nlul~''• new species
Plate 19, Figures 4-6.

Description :-Shell small for subgenus,
moderately convex. equivalve. inequilateral. elongate and trapeziform inoutline; unibo · not strongly inflated.
prosogyrate, slightly incurved and situ·

ate at about anterior 1/3 of hinge;
hinge-line nearly straight: posterior
margin obliquely extended back: anterior
inseparablefrom rounded ventral
margin; umbonal carina blunt: left
valve ornamented by numerous radialribs and several concentric growthlines; radials coarser in anterior sideand fine in postcarinal part: hinge ofGrammatodon-type. i.e. 3 elongate teeth
parallel to hinge margin in posterior
part of right valve and 2 in left.
H

HiL
0.62

22

18mm
14
13

21

11

0.52

23

13

0 57

L

J1!easuremenls :-17:1·---~---

Right vail'e (MM3201)(l\IM3202)
Left
Right
(MM3203)(MM3203)
Left(l\IM320-1)
Left

Observation :-Several specimens showing external at hand are all moulds ofleft valves. The difference on surface
ornaments between both valves is
unknown. but its distinct radial ribs.
not inflated umbo, elongated and obliquely extended form are the characteristics
of Indogmmmatodon. The radial ribs inthe left valve are unusually fine andnumerous for Judogrammatodon. Several
concentric striae cross the radial ribs andlook net-like in posterior.
Comparison:- This resembles Grammatodon (lndogrmimzatodon) virgatus (J. de
C. SowErHJY) (Cox, 1937) in general shape
but radial ribs are much finer. Grammatodon takiensis Kr~tURA from the same
district is very similar to this at a sight.
The more anterior and non-inflated umbo.
obliquely dilated shape and more distinct radial ribs on the middle part
easily distinguish this from G. takiensis.
The middle radial ribs are generally
invisible or very- feeble in G. takie11sis,if· observed. The greatest specimen of

29mm
23

0. 61
0. 59

G. takiensis is no more than 18 mm inlength but all of dens,istriatus in handexceed 20 mm in length.
Occurrence :-5th zone at Loc. 8.

Genus Catella H£'ALEY, 1908
Subgenus Torinosucatella T_,_MI:RA, 1959
Catelfa (Torinosucatelfa)
kobayashii TA~IURA
Plate 19, Figures ;-, 8.
1959. Catella (Torinosucatella) kobayashii, TAl\IUIL-\, p. 55, pl. 6, figs. 11-16.

The external constriction of surface
in the Soma form is weaker than in the
Sakamoto form. The inflation near umbo
is sometimes (MM 3206) prominent.
Ocwrrence :-7th zone at Locs. 13, 1~ ;8th zone at Loc. 14.
Family Nuculanidae
Genus Nuwlana L1xK, 1807

174

Mhwru ·T.tBIUR.l

Subgenus Dac1yomya AGASSIZ, 1840
·Nuculana (Dacryomya)
stenodolicltos KI:-n;RA
Plate 19, Figure 40.
Nuculana (Dacryomya) s/eJwdolichos, KIMURA. p. 83, pl. 1, Jig. 1.
19S9. _Nuculana (Dacryomya) stenodolichos, T A·
r-ic RA, p. 57. pl. 6. figs. 17-19.

1956.

Occurrence:- One poorly preserved
internal mould of a right valve fromthe 8th zone at Loc. 14.

Family Pectinidac
Genus Ch!amys BoLtE:--; MS,
Rooi:-:c, 1798

Chlamys campto11ectaic/es. - T!H.wRl,:~ ne\\: species--------

iUeasU1"C111C1liS :-Left valve (MM3209)(MM3210)Left(MM3211)Right(MM3212)
Right

L

H

18mm 24mm
9
7
9
7
10
8

----

Observation and Comparison :-The rightand left valves differ in shell convexity
and surface ornaments.. The writererected this species chiefly l~ased on its
Camptouectes-like ornaments. As theradial ribs which are stronger than theconcentric ones- in both valves, becomeslightly scaly and run straight, it issure that this can be involved i'n Clzlamys. Pecten sp. (DEciJASEAL:x, 1936) fromthe Oxfordian of Paris Basin is somewhat similar to this species but theconcentric ribs are feeble and radials·
more scaly than 01. camptonectoides.
Occurrence :-7th zone· at Loc. 15 and8th zone at Loc. 14.

_ ~!are 19, Figures 16,- 17.

Descriptioll :-Shell small to medium
in size~ iriec}uivalve, nearly equilaterale~slustx~ q.f:_q_urj"Cies, etongate orbicularand much higher than long. Right
valve dep1'ess~l-:-hinge-tl1a·,:gin straight;
anterior auricle. a.Utrlelanter than posterior; both~ extremiti~s of auricles
acute-angled ; · byssid· sinus' below anterior -aur-icle deep;-- anterior- and. posterior
dorsai margins nearly: straight.: apicalangl!! abo_ut 7W:; :ventral ,margin semicir~ul"ar; SUl:face COVered by -numerous .
(80 or more) radial ribs and- fairly distinct ·concentric ribs; radials slightly
scaly; secondary riblets sometimes inserted. Left valve moderately convex;
concentric lines of grtnvth not so strong
and regular as in right valve; radialribs stronger and coarser and moreregularly inserted by secondary riblets
than in right valve.

Cltlamys sp.
Plate 19. Figures 30, 31.

Shell medium to large for genus,
inequilateral, nearly as high as long,somewhat· quadrate in outline. Right
valve highly infl~ted, inequilater~l andextending antero-ventrally: umbo at
abqut 1/4 from poste~ior ·end; hingeline· ~traight; anterior auricle twice ormore qS long as posterior, byssal sinus
beiow a;1terior auricle deep; dorsal
margins nearly straight and apicala;,gJe ·'go' or less; ventral margin rounded; surface with 30 or more r~dial rib<: ..
T~v~. internai mo~lds of right valve
at hand lack ventral parts. The: inflat- _ed right valve and the l~rge anterior
wing -are ~\YO ~char:acteristics_. The de-tails of the ornaments are, -how~ver, unpreserved. This form, however, differs

37 3.

i 7'5

Taxodonta and Isodonta from the Jurassic Soma Groupdistinctly from Jurassic Clzlamys everdescribed from .Japan in its large andinflated form.
Occurrence :-5th zone at Loc. 5.
Subgenus Radtt!opecten Rou.IER. 1911
Chlamys (Radu!opecteiz)oga~censis (Kir-.tt:RA)

equal ears and shell form, this is very
similar to Entolium japonicum from theUpperjurassic of Sakawa basin (KIMURA,
1951) has no radial ornaments but oneoi Knil:R.'\s specinuen {l\1M7103) resembles this in form. C. sp. aff. brozmi Cox
from the Sakamoto formation (T_.AMURA,
1959) is easily distinguished from it in
the small anterior ear.
Occurrence :-5th zone at Loc. 7.

Plate 19. Figures 23-26.
Acquipecten o.r;awensis, KI:I.ICRA. p. 343,
pl. 1. fig. i.
1959. Ch/amys (Radu/opecten) ogazcensis. T \·;>.It RA. p. 58. pi: 6, fig. 3i.

Genus .4.equipecten FiscHEl~, 1887

1951.

.. A.equipecten" lwtsubu (KI~ll·I~A)
1951.

Pectinids arc poor in the Soma Jurassic in number of both species andindi\riduals. But this species is morecommon ·here than in the Sakamoto
formation, and probably attains 30 mm
in' height. · 'Fii1c growth-lines are distinct and the test is thin· in the Somaform.
· Occurrente :-5th zone at Lacs. 2, 7. 8;o6th zone at Luc. :i; 8th zone at Loc. H.

1959.

Shell medium :c~s in-m long). fairly-convex. :e~uilatera1 · exClusive of ears,-orbicular and higher ·than:lorig :- hinge
IiJatg(n' stniighc anterior. ear· twice· or:more as long as· the· posterior;· dorsal
ma-rgins. straight -and disposed· subrectangul~rfy.:. vent~<ll. pT.ciliably. rounded·;.
surfa~e: .\,;ith. fin~ .. fan-~vi'se-' radiating'l:ibs;.a·short 'tii;e ~idge' an'ci \furro\\.- .be-:low ~inge. margin an j a ridie 7.o.n anter!or. ear of interior .
. The sole internal mot;ld of· t-he Ie.ft
valve at· hand has fine fan-\vise' radials-char~cteristic of the genus ... In' the·un-

kotsulm.

T,\\ll'll.\,p.

Occurrence :-One internal mould of aright valve from 5th zone at Luc. 2.

.. Aequipecten .. vulgaris K1 :v1n~A
Plate 19. Figure 22.

.-kquipe,;tett I'll/garis,

KI~Ili!~A.

p. 3'12,

pl. 1, figs.: 5, 6.
1959.

".4equipecten"

l'ulgaris,T.~\li'IIA,p.

58. pl. 6. figs. 40, 41. ·CamjJ/onectes sp.
Plate 19, Figure 28.

"Aequipecten"

58. pl. 6, figs. 33. 34.

1951.

Genus Camptonecles l\1EEK, 186-1

Neithea kotsubu, KI~IIJRA. p. 3-13, pl. 1,
figs. 8. 9.

Occurrence :-5th zorie at Locs. 2: 7.

Genus EojJecteu Dot.:YILL~ •. 1897
Eopecte11 pzi.nctus (Ki:-.~t'RA)
P.late 19. Figures IS-21.
1951.

r."'pectell Puncta. KI\Il'IIA, p. 3-18. pl. 1,
fig.'21.

Description :-Shell small· to medium,strongly inequivalve. inequilateral. nearly orbicular in outJine.. Hight valve
flat; numerous radial ribs ·a'nd several
weak concentric striae. on surface. Leftvalve moderately convex, more or less

Minaru TAMCR.4

176

diagonally elongated: hinge margin
straight: anterior auricle not clearly
demarcated from shell body. no less than
twice the depressed posterior one: sinus
below anterior auricle shallow; furrow
between shell body and posterior ear
distinct. narrow: apical angle about gooor less: ventral margin nearly rounded
but angulated by radial ribs: these ribs
crest-like on top about 9 and ridge-likein shell body and 1! or so on anteriorauricle; a secondary rib inserted in each
pair: tertiary radials fine: several concentric wrinkles distinct near umbo.
llfeasurements :Left valve (Ml\13220)
Left(MI\13221)

L

H

12mm 13mm
20
19Obserllatiou and Comparison :-A frag-,
mcntary right valve is allied to l•.:opecten
PuncfiiS',Kr~wRA)from thcTorinosu groupof Sakawa. Several left valves allied to
Eopecten in its peculiar ornaments occur
together with the fragments of Eopecten
Pmzctus. Eopecten sp. from the Sakamoto
formation (TAl\HJRA, 1959) differs fromthis species in surface ornaments which
are seen on an internal mould of a leitvalve. They are approximate to thoseof the right valve of Eopecten pundus inform and size. From these facts these
specimens are considered probably theleft valves of Pzmctus. Eopecteu aubryi(Dou\'rLLE) from the jurassic of Cutch
is close to it in ornaments. But the
primary radial ribs are 12 and concentricwrinkles indistinct in E. azibryi.
Occurrence :-5th zone at Lac. 2: 7thzone at Lac. 15.
I

Family Amusiidae
Genus Eutolium MEEK, 1865...

Eutolium yatsujiense KL'RATA
and KrMur~A
Plate 19, Figure 41.

Entolium yatsujiense, 1\I;\I!iRA, p. 346,
pl. 1. figs. 18a, b.
1959. E11tolium yatsujiense, T A :I. II.' RA. p. 60. pl.
6. fi¥. 30.
1951.

Occurrence:- Restricted in 6th zone at
Locs. 5. 16.
Entolium kimurai TA!\WRA
Plate 19, Figure 27.
l!i59.

Entolium kimurai, TA~I!:RA. p. 60. pl.
6, tigs. 23-29.

Two kinds are distinguished in thisspecies from the Sakamoto formation.
Soma specimens belong to the form
whose apical angle is 100o or more andthe height is nearly equal to t~1e length.
It is smaller than the Sakamoto formon an average.
Ocwrrence :-Restricted to the sandy
shale (lOth zone) of Koyamada formation
at Umazawa (Lac. 11) and Lacs. 9. 10.
Genus SomaPecten Kr:-.tl'RA. 1951
Somapecten kamimmzeusis Kr!I·IL'RA
Plate 19, Figure 29.

Somapeclen kamimammsis, KrML'RA, p.
347. pl. 1, figs. 19, 20.
1959. Somapecletz kamimane11sis, TA~Il'RA, p.
62, pl. 6, figs. 50-55.
1951.

Two kinds of shell outline are recognized it} this species, namely, a quite
orbicular form and a tall ovate form.
The latter occurs at Sakamoto,. Yatsuji
and Kurisaka and the other at Sakamo'to
and Soma. Sakamoto specimens aremostly high. These two kinds are probably inseparable specifically at present.

37 3.

Taxodonta and Isodonta from the jurassic Soma Group

Occurrence :-5til zone at Locs. 7, 8 and6th zone at Loc. 1.
Family Limidae
Genus Lima BRucvn';RE. 1793
Subgenus Ctenoides MtlRcH, 18:13
Lima (Ctenoides) tosaua Kr:--.rl:R.\
Lima (Ctenoides) /osana, KnmR.\. p.
349. pl. 1. figs. 22a, b.
1959. Lima (Ctenoides) tosana. TA:\Il:RA. p.
62. pi. 6. tigs. 44-47.

i95l.

Occurrence :-An external mould of :1
broken right valve from 5th zone at
Loc. 2.
Subgenus Plagiostoma SowERBY. 18H
Lima (P!agiostoma) enormicosta
TA.\lliRA, new species
Plate 19, Figures 32-34.

DescriPtion :-Shell large to medium
in size, moderately convex and mostconvex at a little above mid-height.
subtrigonal, height a little less than ornearly equal to length (70 mm long. 65
mm high in holotype specimen); umbonal angle about 90"; anterior umbonalridge well defined and of moderate
length; lunule long; anterior auricle
much smaller than posteriot one whichis indistinctly demarcated with shell
body; anterior margin straight; posterior and ventral rounded but a little
concave in part below posterior auricle;
radial ribs about 30, fairly irregularly
disposed, flat-topped and narrower thantheir interspaces; median ribs and interspaces wider than lateral ones; posteriorauricle ribbed in same way but finer;·1unule finely striated but not ribbed;
margin crenulated roughly; ligament pit

117

1riangular,

fairly large. deep. a little
posterior to umbo and extending posteriorly: adductor scar fairly large.
oblong. located in upper and posterior
side.
Observation :-In most specimens theheight exceeds the length but sometimes
they are nearly equal. The straightradial ribs are characteristic of thisspecies. These ribs and their interspaces become narrower on the lateralsides and the interspaces are wider than
the Tibs.
Numerous concentric "finethreads in the interspaces are characteristic of Plagiostoma. The ribs aremostly flat-topped but fairly rounded insome.
Comparison :-Lima (Plagiostoma) paolii
STEFANr:-.;r (1938) from the Somaliland
Jurassic is very close to it in generalfeature but the flat-topped ribs. theirirregular arrangement and wide interspaces distinguish it from paolii.
Occurrence :-5th zone at Locs. 5. I. 8.
Lima (Plagiostoma) sp.
Plate 19. Figure 39.

Shell large (80 mm or more high),
slightly convex, oblong and higher thanlong: posterior auricle fairly large anddepressed; ribs Tidge-like, about 40. as
wide as their interspaces which bearfine transverse threads.
This species differs from L. (C.J enormicosta in tall outline and mode of ribbing. Lima (P/agiostoma) paolii is closely
allied to it in its shape, radial ribs andtheir number but their interspaces are
punctated in that species.
Occurrence :-5th zone at Loc. 2.
Genus Ctenostreon d'Erc!IWALD, 1862
Ctenostremz proboscidewn (]. So,uR BY)

Minoru T.-BIURA

178
Plate 19. Figure 38.
1820.

i 932.
1935.
1936.
1952.

Lima proboscidea . .T! SowERBY, p. 115,
pl. 264.
Ctcnostreon proboscideum, ARI-\ ELL. WJ ..
p. 145. pl. 15, fig. 3.
Ctc>nostreon proboscidermt, Cox. L. IL p.
1-1. pl. I. fig. 16.
Ctrnostrc>mt proboscideum. DECHASEAL'X.
c.. p. 43.
Ctenostrrmt Pmboscideum, Cox, L. R.. p.
64, pl. 5, figs. 13. 14.

.[!esniplion :-Shell small (ca. 45 mm
long; 55 mm high). moderately convex.
appreciably inequilateral. irregularly
suborbicular in outline and higher thanlong; auricles and umbonal part unknown ; ventral margin irregularly·rounded; radial ribs 10 or more, squamous, high. equal to or narrower thantheir interspaces, covered by concentric.growth-lines which are more conspicuous
on· sulci than ribs.
Obse~L'lltimt :-A sole specimen at handis probably an incomplete right valve
as judged from its obliquity. Whether
the number of its ribs serves for discrimination from Ctenostreon is a matterof discussion. But it is undeniable thatthe number varies in Ctenostreon. Ac.cording to Cox (1952) radials are 12
in typical Ct. probost:ideum and 10 intypical Ct. pectitli/onne from the Inferior Oolite of the type· area (SEGermany). Some Indian pmboscideuni,
however, has 11 ribs. Therefore thewriter referred the Soma form to P.
proboscideum. The vertical r.mge ofpectiniformae does not extend to Malm.
Occurrmce :-5th zone at Loc. 2. Reported from upper Batho'Iii'an or Caliovian to Rauracian of Asia and Europe:

P/icatula dichotomoaJsla TAMt'I{A,
new species
Plate 19, Figures 35-37.

Description :-Shell large for genus(41 mm long, 36 rnm high in holotype),
inequivalve, subequilateral, ovate, longer
than high and a little extending .posteriorly; hinge-line relatively long andstraight; dorsal and ventral margins
rounded. Right valve slightly convex:
attachrnent area narrow; radial ribs
about 20; much narrower than theirinterspac~s.
dichotomizing ventrally,sometimes tuberculate or nodose but
not spiniferous ; several concentricwrinkles intersect radials; internal
margin crenulate ; two ctenoria below
hinge deep and divergent. Left valve
concave, ornamented as right valve .
Obseroation :-External and internalmoulds of nearly complete right valvesbeside a few ·broken valves·are at hand.
The shell outline is very variable. The
holotype is longer than high and equilateraL But lhe··height -often exceeds
the length and the valve is ·elongatedbac-kward. Most ribs dichotomize.
Comparison:- This resembles Piicatula
peregrina o'01wiGNY and Plicatula cos~smmmi LoRIO!- from the Callovian ofSomaliland (STHANINJ, 1938) closely. Its
ribs are more numerous and mostly
dichotomize. The shell is plano-convex
in them. P. cochlear STEFASil"I (1938)
from a little higher horizon than that-of P. cossmmmi is more strongly convex
than this ~ies. .Cox placed thatspecies into P. jJeregri11a (Cox, 1952).
Occmnmce :-5th zone at Locs. 5, 7.
References cited

Family Plicatulidae
Genus P!icatu/a L\MARcK, 1801

W. ]. (!929-37), A Monograph ofBritishCorallian
Lamellibranchia.
l-'alaeo11togr. Soc. Lrmdou.

ARKE!.l.,373.

Taxodonta and lsodonta from the jurassic Soma G1·oup'

Cox .. L. R. (1935), The Triassk. Jurassic
and Cretaceous Gastropoda and Lamellibra!lchia of the Attock district. Palaeonto/. Indica. N. S .. Vol. 20. Mem. :Vo. 5.
(1952), The Jurassic lamellibranchfauna of Kuchh (Cutch). Pulaeontol.
Indica, Ser. 9, .\'o. 3, Pt. -1.
D~:c.HASEAUX, C. (1936). Pectinides jurassi·
ques des lest du Bassin de Paris . .-lmz.
Pateont., Tome 25.
HAYA:\11, I. (1958), Some Hettangian Pelecypods from the "Trigonia-sandstone ·:of the Shizukawa group in Northeast
Japan. Ja/Xl11. four. Geol. Googr., Vol. 29:
KrMURA. T. (1951), Some Pcctinids and a
Limid froin the Jurassic Torinosu Groupin Japan. Jour. Fac. Sci. Uniz•. Tokyo, St;r.
2, No.7.
- - (1954), The Sandstone and Limestoneof the Nakanosa~·~ formation. Jmn-.
Geol. Sec. Japan, Vol. 60. No. 701 . .
- - (1956), Some Pelecypods from the Up-.
per.Jurassic Torinosu Group in Kochi
Prefecture, Japan. jour. Earth Sci.,
Nagoya Unit• .. Vol. 4, No. 2.
KoBAYASHI, T. & T.HviVRA. M. (1955), The
Myophorellinae ·from North Japan.
Studies on the Jurassic Trigonians inJapan. Pt. 4. Japan. four. Geol. Geogr.,Vol. 26.
-- & (1957). Additional New Genera

179

Trigo~ns

and species uf
from theJurassic of Soma, North J an. Studies
on the Jurassic Trigonia
in Japan,Pt. 6. faP(ll!t Ju.u!i.• O,Oir(ie~•.. Vol~ 28..
LoRror .. P. et.'•Pr~Lr:tt, lj:. ·(1875)', D~scrip:tion des fossiles. Mollusques Acephales.
In P. de LORIOL and ~: PELLET, Mono·graphic paleontologique et geologiquedes etages superieurs de Ia formation
jurassique des en\•irons de BoulognesurMer. .Hem. Soc. Pi1ys. Hist. Nat. Geneve,
Tome 24.
MAsATAl\1. K. (1950), A ·Study of the Ju. ras&ic Forma~ions in the SoV~a District,
Fukushima Prefecture .. jour. Geol. Soc.
JaPan. Vol. 56, l'{o. 662.
SowERnY. ]. (1820), Mineral Con_chqlogy ofGreat Britain, Vol. 3, London.
.STEFAl\1~1. G. (1939), !'.,1oll.usc;hi_<lel Giuralias della Somalia: Gasteropod c LameUi'
branchi. Pal. Ita/., .32. Supp/..4.
TAML'RA. M. (1959), Taxodonta and lsodonta
from the Upper Jurassic Sakamoto
Formations in Central Kyushu, Japan.
Trans. Prnc. Palaeont. Soc. japan, N. S.,
No. 3.J.
YABE. H. and SATo, S. (1942). A New Bivalve from the Jurassic Torinosu Seriesof the Abukuma mountainland, Proc.
Imp. Acad. Tokyo. Vol. 18.

Explanation of Plate 19
Grammatodmz takiensis KlliiU!~A
Figs. 1, 2. Interriai mould and clay cast of. an, external mould oi a left \'alve; .·Loc. 1•2;
x-1<5. (¥M3199). •.
Fig. 3. lnter~al mo~_ld of a bivaly~<!; ~J,lell i _Loc;. 11; x.l.5. (MM32tl0).
Grammatodon.(lndogrammatodon) densistrialus' 'I_'A:<.,Il.J·RA; Il!!W'species'
Fig. 4. Clay cast o'f an' ex' tern~ I mould ;;f ·~ ~ew· species holotype; left valve; ·Loc. 8;
xl.5 .. (MM3202). •· .. · ,Fig. 5. ·lnt~nial· mouid of a bivalved shell; Loc. 8; x 1. (MM3203).
Fig. 6. Cia~ cast of a lef~ valve; Loc. ~8: !<1::- (~IM3205).
Catella (Torin.Osucatella) kobaytnmi TA~IUR,\.
Figs. 7, 8. Internal moulds, of left- yalye:s· (~th-·thin test fragments): Loc. 15: xl.5.
(MM3206, 3207).
Parallelodon koikensis T AMlJRA, new species
Fig. 9. Internal mould of a hi'~k~n· right valve (with thin test fragments); Loc. 15;
X.L5: :(MM3194).

Mi1wrzt TAMURA

180
Fig. 10.

hiternal mould of the holotype left valve (with thin test fragments); Lac.

1!;'; X 1.5. (MM3193).
Fig. 11. · Internal mould of the holotype left valve (with thin test fragments); Loc. 15:
xl.5. (MM3195).
Parallelodon sp. aff. i11jlatus T.-\~lt;RA
Figs:· l2. 15. Clay casts of the external moulds of left valves; Loc. 12; x 1. (MM3197,
3198).
Figs: 13. 14. Internal mould and the external mould of a right valve; Lac. 12; x 1.
(MM3196).
Chlamys camptonectoide,~ TA~tlJRA. new species
Fig. 16. Internal mould of the holotype right valve with thin test; Lac. 14; X 2. (MM3212).
Fig. 17. Left valve; Loc. 15; xl. (MM3209).
Eoper.ten Jnmdus (Kn.tt:RA)
Fig. 18. Interior of a broken valve; Lac. 15; X I. (MM3222).
Figs. 19. 21. Internal mould (xl.5) and clay cast of an external mould (X1) of a left
valve; Loc. 15. (MM3221).
Fig. 20. Left valve; Loc. 15; x 1.5. (.l\-1M3220).
"AequiPecten" zwlgaris KJ:\IIJRA
Fig. 22. Internal mould of a left: valve; Loc. 7; X 2. (l\1M3219).

Clllamys (RaduloPeclen) ogawensis (KIMURA)..•

Fig. 23. Internal mould of a left valve; Loc. 5; X 1.5. (MM3215).
Fig. 24. Internal mould of a valve; Loc. 8; x2. (i\IM3216).
Figs. 25, 26. Clay casts of an external and an internal moulds of a left valve; Loc. 14:
xl.5. (MM3217).
H11lolium kimurai TA:I-IIJRA
Fig. 27. Internal mould of a left valve; Loc. 11; X 1.5. (MM3224).
Camptonectes sp.
Fig. 28. Internal mould of a left valve; Loc. 7 · X 1. (Ml\13218).

SamaPecten kamimatletiSis Kt~Tt:R.\
Fig. 29.

Internal mould of a left valve: Loc. 8; xl. (:\L\13225).

Chlamys sp.
Figs. 30, 31.

Internal moulds of right valves; Loc. 2, 5; xi. (MM3213; 3214)

Lima (Piagiostoma) enormicosta TAi\IIIRA, new species
Figs. 32, 33. Clay cast of an external mould of a left valve and an internal mould of aleft valve; Loc. 2; X 1/2. (MM3226. 3227).
Fig. 34. Internal mould of the holotype right valve; Loc. 2; X I. (MM3228).
Plicatu/a dichotomocosla TA~tt.:RA, new species
Fig. 35. Clay cast of the external mould of a right valve; Loc. 7; X 1. (MM3232).
Fig. 36. External mould of a left valve; Lac. 7; X 1. (Ivil'.'i3233).
Fig. 37. Internal mould of the holotype right valve; Loc. 7; x 1. (MM3234).
Ctmwstreon proboscideum (J. SowERBY)
Fig. 38. Clay cast of an external mould of a right valve; Lac. 2; X1/2. (:t-.iM3231).
Lima (Piagiostoma) sp.
Fig. 39. Clay cast of an external mould of a right valve; Lac. 2; X 1/2. (.Ml\13230).

NttculatuJ (Dacryamya) sle11odolichos KIMURA
Fig. 40.

Inte·rnal mould of a right valve: Loc. J.l; x2. (MM3208).

Eu/olium yatsu}itmse KL'RATA and K1~1l:RA
Fig. 41.

Internal mould of a left valve; Loc. 16; x2. (I\IM3223).

All specimens here illustrated arc kept in the Geological Institute, University of Tokyo.

T AMURA :Upper Jurassic Pelecypods

Plate 19

Trans. Proc. Palaeont. Soc. Jap:m, N. S., No. 36, pp. 181-184. pl. 20, Nov. 30, 1959

:374.

TWO NEW PERMIAN CORALS FROMYA}IAGUCHI PREFECTURE*MICHIHIRO KAWANO!*.

Faculty of Education, YamagUf.:hi University

Lll IJt1iUi1=!i!t~JlHlflilO) 2 tliflli: rLI I::!J!iUt$0)1iAJJl<!:IBJWi~Jq;J'i[id: I)

cv t:. I'll lH lOO fllllluangia? o.>tTN! H. ? kall(msis~Mlflllflil Pseudopat•ona /aisyakuana o.>tfill!fill P. tai·syalmana izutoensis ~&a~ l.d.: o c t, r:.lli!JEF®llfF-$o.>&1f:fMrflO) v :..- ;;(tt:PEK~ d: '> ~ v
t: {,0)1:, C::.01iER~tJ>I;1;t Neoschwagerina margaritae (DEPRAT) ~~i'oOJl:lliH~I;t.::5!Hi:lr:fltfll c!: ~ ::t I; tL 7.> o ~I;*, PseudoPat•otza li taisyaJma11a 0) 1 li!!O).;j.:!J;:p.JRjCr:fli$J:l)if1~~~1.Lt,t.:,j'iiJ !llf iili !Jl,,,,~·~o·Introduction and Acknowledgements

During the writer's geological studiesof the Paleozoic rocks distributed in the?vJino-Kanoashi l'vlassif in the westernpart of Shimane Prefecture and thenorthern part of Yamaguchi Prefecture,
fossils of fusulinids and corals werediscovered from the Izuto I i mestone.
The limestone is a lens embedded in·the Kane formation and has yielded
corals of the genera PseudoPm•otta,
Hua11gia ?, Waageuophyllum and others.
among which two new species aredescribed in this article.
The Paleozoic formations developedin the southwestern part of the above
stated massif have already been report·
ed by. the writer (KAwA:-.:o et al.. 1956).
Among the Paleozoic formations theKane is particularly fossiliferous in its
two limestone lenses. The formationconsists of sandstone, slate. chert andlimestone lenses. Its general strike is'N 40'-60oW, and inclines at angle of 50°-60'NE. constructing in the Kane district a monoclinal structure. Near Kane

,J

,.~-

Text-figure:~tma.~ Pre!eet.·.r"!

Map showing the locality.

there are two limestone lenses, thelower is known as the Kooda limestone
and the upper the Izuto limestone. The
former is typically developed at Kooda
and consists of limestone conglomerate
or limestone breccia, from which thefollowing fossils have been discriminat·
ed, namely:
Climacamilta sp.
Oiawainella sp.
Sclmbertella kingi DuNBAR and SKJX:"ER
Triticites cf. ellipsoidalis ToRJYAMA
Sduvagerilta krotowi (ScHEJ.I.WJEr-;)* Received at Jan. 29, 1959: read at theAnnual Meeting of the PalaeontologicalSociety of Japan at Tokyo, Dec. 7. 1958.
181

182
Schwq.gerina sp.
Pseudofusulina ·vulgaris (ScuEr~~,owic::-.:)
P. vulgaris var. g!obosa _(ScHELLWIE:-.:)
P. vulgaris var. megaspllerica ToRIYAMAPara[usulina sp.
Pseudodoliolina ? sp.
Corals gen. et sp. i ndet.
The lzuto limestone is developed atabout 300 meters north of the Kooda
limestone. This limestone is a lensmeasuring about 70 meters in thickness
and about one kilometer in length andconsists of white slightly crystallized
limestone barren of fossils· in general.
However, at the Abu limestone quarry,
it contains small dark gray masses with
densely crowded specimens of Neoschwagerina mmgaritae (DEPRAT), Parafusulit~a sp., Sdzwageritw sp., and others.
Hulmgia ? n. sp. was obtained from thislocality where it occurs in association
with Neoscluoagerina margaritae (Dc:PRAT).
About 50 meters north of the Abu limestone quarry there occur abundant remains of crinoid stems, Waageuophyl/um
and PseudojJ(lJ}ona. the latter of which is
described in this article.
From the evidence afforded from thefusulinids, the Kooda and lzuto limestone indicate that the age of the Kane
formation is Middle Permian.
· The writer wishes to express his mostsincere th;.mks to Prof. Motoki EGucm
and ·Prof. Kotora HATAI of the Tohoku
University, whO gave their kirid suggestions 'at:Jd criticism concerning the corals
dealt with and read through the typescript.
Description of the Species

Order Tetracoralla HAECKEL
Family Clisio.phyHidae NicHoLsoN
and T~OMSON, •1883

Genus Ifmmgia YAnE, 1950
Iluangia? kanensis KAwA:-.:o, n. sp.
Plate 20. Figures 3-8.

Corallum fasiculate, corallites usually
aggregated cl~sely. Corallites rather
small, calicular diameter ranging fromfive to six millimeters at maturity.
Calyx· deep, wall thick. Septa in twoorders. Major septa extend to centralarea, some. unite dir~ly with septal
lamellae of columella at matu'rity. notjoining wi~h-columella in young. Minor
septa short, developed at maturity.
Columella solidified by stereoplasma,loosely constructed and irregularly ofaxial tabellae and septal lamellae,
median plate present but not typical.
Dissepimentarium broad. Tabulae present but sparse.
In longitudinal section. dissepiments
loosely arranged in one or two orders,
their convex sides facing inwards.
Tabulae arranged sparsely and descending steeply towards columella. their convex sides facing inwards like dissepiments to construct central column.
Calicular diameter and corresponding
major septal number of each corallite
are as follows.
2.8 mm ........ 12
3.0mm ........ 14
3.6mm ........ H
3.6mm ..... , ... 16
4.0 nun ........ 16

4.0mm ........ l7
4.6mm.
. ..185.0 mm ........ 20
5.2 inm ........ 20

Remarks :-In transverse section tl}.e
present new species resembles Yatsengia
asiatica HeANG, the genotype of Yatsengia
Yo11 and llt:Al\'G, 1932, and Yatsengia
ibukiensis MII"ATO. reported. from .thePara[usuli1w zone of the Ibuki · djstritt
and othe localities in Japan. ·But inlongitudinal section;the present speei~scan be distihguished 'therefrom by the374.

Permian Cwals frmn Yamaguchi_parallel and slightly cur.ved. Tabulae·and dissepiment~ pre.sept in .axial partard sometimes in i!)terseptal part.
Remarks:- The ·genus Pseudopavmw
was originally established by Y ABE.
SuGIYAMA and EGucHI (1943) based upona hexacoral-like Carboniferous coralfrom the Taisyaku limestone, and for it
the new family Pseudopavoniidae of the,order Haxacoralla was introduced by,them .. · Hithert~ ···only the genotype,· Pseudopavona tai$Y{Jkumw YA BE, SuGt~·,ntA .and EGuc'H, · ~. been recorded
from japan; this is ~a Midd-le CarboniOrder Hexacor~lla f!,\ECI<EL
ferous species. Aside from its type
Family Pseudopavoniidae Y:"-BE,·locality; T.'YoKOYAMA (1957) recorded it
SucD'AMA and Ecuc-HI, 1943
from other localii:i~ of the Taisyaku
limestone. The new sUbspecies describ·
Genus Pseudopavo1m YA~E. StiGIYAMc\ ·'ed in this article senr~i to extend theand EGt:cHI.- 1943
geological range of the genus up to theMiddle Permian .
.PseliC!lJjJavotZa taisyakruma izutoensis
The material now at hand in having
KAwANo. n. subsp.
rtieattdroici corallum, corallites lacking
a ptoper wall and. being connected by
Plate 20. Figures 1, 2.
confluent trabecular septa, show conCorallum composite. massive, meansiderable resemblance with the genotype
droid. Corallites small, three to fp~r ,.. 'species, Pseudopavona taisyakumm. Orimillimeters from center of adjacentot~astral'a sp. described by l. H.'\ L\S,\KA
corallites. calices arranged sporadically.
(1932) from the' Omi limestone shows
In transverse section. each corallites
superfitifl,i ,teserrtqlance with the present
with no wall, connected by perfectly
sp~cies.
confluent septa. Diameter of calices··Compared -With the Taisyaku species.
less than two millimeters. Calicular
the present .specimens are smaller inarea with 10-20 septa. distinction. be·size and exhibit a somewhat different
tween major and minor septa not clear,structure of the calices. by which it isapparently disposed radially and almost
distinguished therefrom.
straight. Some septa in contact with
In association with the present new
subspecies there were found Waagenocolumella. structure indistinct. Tabulae
p!tyllmn sp. and other unidentified corals
partly present.
Septa of so-called
and abundant remains of an unidentified·t-rabecular septa. trabeculae consist of.crinoid, mostly r'epresented. by its stems.
distinct fibrous tissue. exhibit sawFrom the occurrern:e of lluat'!,ria?
teethed structure on both sides of septa
katumsis KAwANo, n . sp. in associationin outer part of calicular area.
with Neoschleagerina 11f~WgtWitae (DEPR.u)
In longitudiual section, septa composedfrom the-Abu limestone quarry, whichof numerous trabeculae consisting ofradjating fibers, nearly straight, subbelongs to the Izuto limestune. it is..details of its structure, which are. most.rela~ed .to _the. g_e_~us Huangia YAaE.
1950. The · c,ha.ract~rs.- d~~p·ibed · above
are remote from any previously de·scribed species of Huangia and therefore. the writer refers it to the named
genus with the reservation that it may
represent an undesctibe'd genus. 'bccummce:-Limestone at the Abu
quarry, Izuto, ·District, Ato-cho,
Yamaguchi Prefect'li.re.

Kane

•

.,...

'

I

,

'

•-

iv!ichihiro K4 WAND

18t

considered that the Izuto is l\Jicldle
Permian in age and referable to tl1e
Neoschwagerinrr zone.
Occurrence :-Izuto limestone of theKane District. Ato-cho, Yamaguchi
Prefecture.
References
H.'\ YASAKA, I. p932), An a~tiaei'form Coral
from Central JaP.an. Geol. Mag.. Vol. 69.
Ht-Al"G. T. K. (1'932), Permian Corals ofSouthern· china. Pal. Sinica, Ser. B: Vol.
VIII. fasc. 3!
KA:o-JEJ, T. (1957), On Two Permian Corals
from the Mizuyagadani Formation. Jour.
Shi11shu Unh•., No. 7.
.KA\\'Al-:0, M.. TAKAHASJ, E., l'v1L;R.-\KA:'Ill. A.
and NAGAO, M. (1956), Paleozoic Formations of the southwestern part of the
Mino-Kanoashi Mountainland. (in Japanese, with English abstract). Bull. Fac.
Educ. Yamaguchi Univ., Vol. V, No. II.

Ml:-.!ATO." M. (1955), Japanese Carboniferous
and Permian Corals. Joitr. l•ac. Sci. llokkaido Unit•., Ser. 4, Vol. 9, No. 2. ··NAGAO, T. and MJNATO, M. (-1941). Cont·enia
hasimotoi, a new Tetracoral from theUpper Paleozoic of Sikoku. jour:. Fac.
Sci. Hokkaido Univ., Ser. 4, Vol. 6 .. No. 2.
YADE. H., SUGIYAl\lA, T. and EGUCHJ. M.
(1943). A new Hexacoral-like Carboniferous Coral (Preliminary note). (inJapanese, with English Resume}. jour.
Geo/. Soc. Japan, Vol. 50, No. 600.
YABE, H. (1950), Permian Corals resembling JVaage1wpllyllum and Corwenia. Proc.
Japan Acad.. Vol. 26, No. 2-5.
YoH, S. S. and HuA!'G, T. K. (1932). The
Coral Fauna of the Chihsia Limestone of
the Lower Yangtze .Valley. Pal. Sinica,
Ser. B. Vol. Vlll. fasc. 1.
YoJ..:OYAMA, T. (1957), Notes of some Carboniferous Corals from Taishaku District, Hiroshima Prefecture, Japan. four.
Sci. Hiroshima U11i1J .. Ser. C, l'ol. 2. No. 1.

Explanation of Plate 20
Figs. 1, 2. Pseuclop(WOIIlJ taisyakua11a izutoensis KAWANO, n. subsp.
1: Longitudinal section: x-1·.
2: Transverse section: x4
Figs. 3-8. Hua11gia? ka11e11sis KAw A:"O, n. sp.
3: Longitudinal section: X 4
4. 6. 7; Transverse section: x4
5, 8; Transverse and longitudinal sections: x4

K AWANO:

Permian Corals from Yamaguchi

Plate 20

Tram;. Proc. Palaeont. Soc. Japan. N.S., '1\o. 36. pp. 185-191. pis. 21. 22. Nov. 30. 1959

:375.

ELECTRON-MICROSCOPIC FINE STRUCTURE
OF FOSSIL DIATOMS. VI*
Stereoscopic Observation
HARUO OKCNO
Kyoto University of Textile Fibers

1t1.JH~o:>ffi'rWJi~t(!((:J~~llti~·

VI: ~ffil*''?'ffl-r-t--7-Jvllti77 t:1 :..-lllfftih' 15 iJl!l

0i11!.r.'iU!Eo:>J'.ll~±l:: ~1il;n: ~;t tt ~ lit*f>tft'Efflii

Terpsilwe americana. Diml'rogramma
dubium. Navicula maculata var. gigrmlea ..4mPhora proteus. Surirella striolula var.
bret•is. Campylodiscus Kiitzingii &V' -t- 0iftifii! var. cocconeiformis 0)11Ff~fi!Qlf.Ji!'t!fill
TM.rti.:t>J~ Ld:. ~[!]fJ: -t tt.ftto:>.ftE~~:::-:n '-rm.:rl1i~~Hlit1Lf*?4~H!Nm~l:: J: ~ tr'lf.iHi'· •. Hdllio:>i'£f*((~~~~m~.:t>1J·t..: IJ <. :b L- <. Jlf!lfJJ:lT ~c..!: n:t±HlU.:. !Jf:f'GI:.ffl•. 'f.:fEAH-.Ii;(±:~-:-o:>rl~\~!.IH'.·l:iTJ~*OO:tv-1-v-7 · 7J-:t':/~ft~8l!h"YJ ':7:..-t\;J: '>'*lrl~:t't.t.:t0"t'J~IJ .!Jj]J:(;0)$1~;&.1::ttG"C/'!f!O~~iO)!@:~i{i"~.
!!'! !J.ff li: !tt

This study is based upon the crude
diatomaceous earth· sent me from Mr.
R S. l\IAcMJJ.LAN 1> in 1957. In his explanation about the earth. he wrote as
follows: "The deposit is located in thestate of Nevada, in Churchill County
about 15 miles south of the town of Fallon. It is thought to he either Upper
Miocene or Lower Pliocene. I find this·occurrence to be most interesting of any
lake deposit which I have so far encountered. This is the only diatomite.
of this character. in the · Basin andRange Province'. so far as I know andI have examined several hundred occurrences. No development has been doneon this deposit. It is badly contaminated with acidic volcanic ash and has otherimpunt1es. It was possibly deposited
during the later brackish or saltwaterstage of a previously fresh water lake.

* Received Jan. 26, 1959; read at the 7lst
Meeting of the Palaeontological Society ofJapan, Sept. 27. 1958. at Kyoto.
1) The original collector of the present
diatomaceous earth; Geology and Quarry
Operation Dcpartmerrt. Great Lakes Carbon
Cooperation. U.S. A.
185

The formation is locally known as the·Truckee·, farther to the south the correlating formation is known as the·Esmeralda·. Numerous fresh water
diatomaceous deposits occur in botha,reas.''_ The diatomaceous earth (Specimen. no.
DL-7243; Okuno-m 1168) is white powder
Qf fine particles, and all the fossil diatoms found in it are salt-water littoralf_orms, without remarkable dominant spe·
cies. The earth is almost purely comrosed of fossils of Terpsinoe americmut.
Dimerogramma dubium, NatJirula macttlata
and varr. acttla, gjga11tea, i11jlata, Amphoraproteus. Surirel/a strialula var. brevis.
Campylodiscus Ki4/zit~gii and var. cocconei·
fomzis. most of which are found in fragments of their frustules or valves (Text·
fig. la). Judging from such components
and from the absence of fossils of planktonic diatoms 2>, it may be fully conclud2) For example. Aclin~cyclrts. /lctinoptycus.
Arackt1oidiscus. 'Coscinodiscus, StepJwnopyxis.
':[ricerqlium, which are often found predomi·
nantly- in many of the marine diatomaceous
earth.

18()

Haruo 0KUNO

ed that the earth, whether it may be ofprimary or of secondary deposition, isoriginated in a littoral saJt:\\;ater.
For the full elucidation of three dimensional character and spatial relationof the elements of fine structure of thefrustules. I present here the electron
stereo-micrographs of all diatoms dealt
with. The pair of the stereo-micrographs was obtained-by taking two plane
micrographs of each ..frustule at thesame magnification.· tiiting·the frustule
about 12 degrees in the electron microscope. between the first and second exposures. View each pair of the stereomicrographs through a stereoscope withparallel or crossed' visual axes. _ By theview with a stereoscope of parallel visual axes. the image wi II be exactly thesame as the explanati(m of the "inside'
view,; ·or' the "outside view .. in thePl.ates'.l On the contrary. by .the view'\Vlth a stereoseope"ofcrossed VIsual axes.
the image will_be opposite to tl~e ex-:planation. Further, one can get a stereoimage from the stereo-pair of the micrographs with the naked eyes. after sufficient training of the adjustment of eyes(cf. 0Kt::-:o, 1959, Bot. 1l1ag. Tokyo, vol.
;-2. pp. lil-62.).
I wish to express my thanks to :t\Ir.
R. S. l\L\cMILI.AN who kindly sent me
the original sample. This research \vasaided by a grant in Aid for Scientific
Research from the Ministry of Education.
Description of Species

Terpsinoe americana (BAILEY) RALFs
Text-figure• 1 b; Plate 21, Figure 1.

TerPsinoii americana (B :\ 1 LEY) R :\ L F s, A.
ScmiiDT, 1895, Atlas Diat.. pl. 200. figs.
9-13. -PA:>;TocsEK, 1903, Foss. Bacill.
Ung., vol. I, pl. 6, fig. 53. -PERAG.\LLO,

1908. Diat. mar. Franc~; pl. 90, figs. 5. 6.
--BOYEI~. 1916. Diat. Phi lad .. pl.6. fig.lO;
1926. Synop: North A mer. Ilia! .. pl. I. p.
145.-llt:sTEDT.l93U. Kicsclalg .. pt. l. p.
900, fig. 541.-MILLS, 193-1. Index. p. 1597.
- ._-ZHt:SE,

PROSCHKJ:-o:,\,SIIESIJL KOV :\,1949. Diat. Taxonomy, pt. I. p. 169. pl. 10,
fig .. 3. --CLEVE· Et'LER.
1951. Diat.
Schweden u. Finn land, pt. I. p.l:?S. fig. 288.

: Frus~ules quadrangular ·in girdle view.
with sep_ta ingrowing :about ·haJJ:-, way. into the·· valve. Height· of '.the 'fn1stule
about 80.u. Valves·eiJiptic. about' so.:I25tt
long. and about 45--60.u bi·oad, with triundulate margins and rostrate ends': divided by two septa into three 1 segments.
Central area of the valve hyaline. roundor irregularly bordered. Valve surface
with radial rows of· fi.ne :rr·usttile: pores
about 7-12 in lOtt. : Near::the end--of thevalve. the rows of · phi'es: ·ufteti- interrupted b'y a trans,rerse 11yalll1e'space.
Electron opt.ically. ·the· f1~ust'u!e jJore
seems to. be smile,(rJiat- locular.' closed
outwards by a tliih iri·egulai·I)• porous·
sieve membrane. mid opens·(~llmost' free-·ly ?) inwards with rotind 'opehing about.
200-400m,tt in diameter. hi the present·
research, the details of the lateral wallof the loculus could not be discerned.
In many valves the sieve membranes
are well preserved.

aDimemgyamma dubiwr1 'GRl':-:ow
Text-figures 1c, d; :flate ?L Figures ~a. b.

Dimerogramma dubium 'GRU!\:0\\'.· VA="HEURCK, 1880-1, Syn. Diat. Helg.; pl. 36.
fig ..18.--PER 1\GALLO,l897-08. Diat. mar.
France. pl. 82, figs. 8, 9.-llusTJo:DT, 1931.
Kieselalg., pt. 2, pJ122, fig. ,645 .. -MILLS,
1934. lridcx. p. 603.

Frustules quadrangular in girdle view,
united in short chains: Valves~ linear,with parallel margins and cuneate ends;

37 5.

Electron· Microscopic Fine Structure of Fossil Diatoms

187

Text-fig. 1. a. Crude earth (x50). b, Terpsinoe americana (x500). c. d.
J>imerogramma dubium (c. Valve view. d, Chain of frustules. x500). e . .4mpltora
proteus (X400). f. Surirel/a slriatu/a var. brevis (x500). g, Campylodiscus Kiitzingii( x800). h. var. cocconeiformis (X 1000). (a-1:, Lig!1t _micrographs)

about 80-90.tt long_ and 7-lO,tt broad.
Pseudoraphe narrow.· about ·().3:U broad,sometimes ind isti'nct. Electroil·optically, the frustule pores rounded-rectangular or elliptic, about 450.:660m,U long and200-330m.u broad, arranged in transverserows about·7~10 in-lOp. -The-pores-seemto be more or less locular. closed probably outwards by a thin sieve membrane with nelveins. and ope!Jed freely,probably inwards. In many valves. thesieve membranes are 'wen' preserved.
The valve,- on its margin, with an annular row of .dent_if_orm spines.. The
spines lamellar, about 2.5.u .long, about
l.u broad. and s...:10 in JO.u; each with abroad basis and a pointed or truncate
end. Electron micrographs of such ·dentiform spines of .Fragilai:ja constrzeens,crotmumsis and Cymatosira 'belgica · arepublished by HEL~tcKE ~n~ KRIEGER in
their Diat. Elektr. Bild. pt. 2, pis. 141.
142. 149:-

Navir:ula macu!ata (BAtLEY) CLEVE

var. gigantea 0KuNo
Text-figure 2A; Plate 21, Figure 3..

·.v~vicula maculata (BAILEY) CLEVE var. gigantea 0Kc;.;o, 1956, Trans. Proc. Palaeo11t.
Soc. Japan, N. S., No. 21. p. 134, text-fig. 1,

Haruo 0KUNO

188
pl. 22, figs. 5a-c.

I already reported some fine structureof th.~ .frustule wall of the present va:
riety revealed by the electron plane=
n1icroscopy (OKu:No, 19B6). In the present
eleCtron stereo-microscopy, I could finda complex structure of the frustule poreas shown in Text-fig. 2A: The frustulepore is Jocular, somewhat deep funnelshaped, and seems to be partition~d bya half -clos!'!d central membrane· into theouter and inner vestibules. The outervestibule infundibular, ope!1ed almost:r~.x~·fig. 2.·. Di~gram of the fine struc.ture of loculi. partially presumedly
represented. A .. Nal'ic11la macula/a var. gigantea (cf. Pl. 21, fig. 3). B, Amphoraprotetis (ct."' PI. ·zz·. fig. 1). ca. Ccnhal area.· nn. Central memhriu1c. co, Ccritral
opepi_ng. · im, liiner.membrane. io. Inner opening. it•. Inner vestibule. om. Outer
membran~. 00, Outer opening. 01'. Outer vestibule. rl. Radial.iamella. sm.~Sie\·emembrane.- sp, Sieve pore.

Explanation of Plate 21
Pairs of electron stereo-micrographs.
Fig. 1. Terp~·inoe-tlJ'IU'Ticana (R.AILEY) RALFS. Valve: inside view. (x12500) .
Figs. 2a, b. Dimerogramma dubinm GRt;l'OW. a, Girdle and mantle; inside vie~? b, Valvemargin, showing spines. (a, x4500. b, x6000)'
Fig. 3: Navicula maculaia (BA 1LEY) CLEVE var. giga11tea OlwNo. Valve; outside view. ( x 7500)
Loc. (Figs. 1~3) · 15 miles south of Fallon, Churchill Country, Nevada. U.S. A.

Plate 21

Fine Structure of Fossil Diatoms

OKUNO :

''

r~

I

)

'
'

·:1

'

~

.:•

'

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~

·.?

t.

.

,......-:

~

:,i')

..

~)

.~

\

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IJ)

'

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..•

f'h

.;;-,

m
;Jit

;.j\

......'

~\

*l

:tl

.,

•••

~·

'1\

..........
,

I

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.;

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:«t

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:J

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375.

Electron-MicroscoPic Fine Struditre of Fossil Diatoms

freely outwards, and more or less closed
inwards by the central membrane. The
inner vestibule probably cylindrical,
with · marginal radial lamellae which
divide the vestibule into about 7-12
sectors. The inner and outer vestibules
communicate each other through thecentral opening. The bottom of theinner vestibule is incompletely closed
by a delicate inner membrane with radial and marginal slit-like sieve pores ofvarious shapes and sizes (cf. 0Ku:-~o. 1. c ..
text-fig. lB). The central area of theinner membrane usually roun.d, scatteredwith fine sieve pores. The fine structureof the type species, varr. aruta, in/lata
are found to be the same to the present
variety.

18:1

Ius with a linear opening, about 100200 1111.1 broad : the inner sieve membrane
is perforated by numerous round sieve
pores arranged in three lines (about 4050 in l,u) decussating at about 60 degrees (Text-fig. 2B). In many valves theinner sieve membranes are lost. In living forms of Amphora ova/is and var.
pediculus. the sieve membranes of thesame structure were found by Hr:c:o.tcKE
and KRIEGER (Diat. Elektr. Bild. pt. 1.
pl. 77. pt. 2. pl. 181).

Surirel/a stria/uta TuRPI:-: var.
brevis (EHRENilER<.) D1:: ToNI
Text-figure lf·; Plate 22. Figure 2.

SurireUa strial1tla TuRPI:-: var. brevis (EHREN-

A.mp/wra proteus GREGORY
Text·figures 1e, :.m; Plate 22. Figure i.

Amphora proteus G11EC.ORY, A. ScliMIDT, 1875.
Atlas Diat., pl. 27, figs. 2, 3. 5. 6. --MILLS,
1933, Index, p. 180.-LAVTIENKo. 1951.
Freshw. Diat.. p. 415. pL 257, fig. 1.
Amphora proteus var. Kari11a GIHJNow. 1880.
Arct. Diat., pl. 1. fig. 7.

AmPhora Proteus var. oculata, PERAGALLO,
1908, Diat: mar. France. pl. 44, figs. 21, 22.

Frustules elliptical in girdle view,
with truncate ends. Valves lunate. eachwith slightly concave or almost straight
ventral margin and convex dorsal margin: length 120-130,u. breadth 20-25,u.
Raphe biarcuate. Central hyaline area
distinct on the dorsal side. Axial area
indistinct on the dorsal side, broad andirregularly bordered on the ventral side.
Frustu Je pores arranged in transverse
or slightly radiating rows, about 8-10
in IO,u. Electron optically, the frustulepores locular, linear or linear elliptical,
about 0.5-3.0/.l long and about 0.5-1.25,ubroad. The outer membrane of the locu-

DE To;-.;1, AzPEITI.-\, 1911. Diat.
Espanola. p. 200, pl. 12. figs. 8, 9. MILLS, 1934, Index, p. 1540.
BERG)

Valves broad obovate: 48-lOO,u long,
48-80,u broad. Wings indistinct. Costae
about 7-10 in lOO,u. with distinct rowsof striae (about 7-9 in lO,u) between
each two costae. Central space more orless broad lanceolate. Valve surface
scattered with fine spinules. This variety can be distinguished from the typespecies by its broad central space. Electron optically, the radiating intercostal
spaces were ellucidated to be incompletely locular, closed outwards and ope1~ed
freely inwards. The loculus shallow near
the central area and deep to the valve
margin. The outer closing membraneof the loculus is perforated by 4-8 transverse double rows of round sieve pores
about 50-lOOm,u in diameter. In eachrow, the pores about 5 in l,u. HELMCKE
and KRtEGim?s electron micrograph of S.
striatula (living form) in their Diat.
Elektr. Bild. pt. 2, p. 18, pl. 200, sfiows
sieve pores without closing membranes

Haruo 0KUNO

190
as those of the present fossil.
Campylodiscus Kiitzingii
BAILEY et I-L,RvEY

Text-figure 1g; Plate 22. Figure 3.

Campy/odiscus Kiitzingii BAILEY et HARVEY,
PA:--:TOCSEK, 1903, Foss. Bacill. Ung.,
vol. 3, p. 26. pl. 30, fig. 433. --MILLS,
1933. Index, p. 343.
Campy/ndiscus striolatus GRliNO\\', A. ScllMIDT,
1878, Atlas Diat., pl. 53, figs. 1, 2.

Valves elliptical or suborbicular, 1750tt long. and 16-60tt broad: transapicalaxis is longer than the apical axis. Frustule pores arranged in slightly radiating rows about 13-18 in lO.u.
var. cocconeiformis OKuNo, var. nov.
Text-figure 1 h.

Valvae cocconeiformes. ca. 17-50tt
longae. ca. 16-30tt latae: axis apicalis
longior quam axis transapicalis.
In this new variety, the apical axisof the valve is always longer than thetransapical axis. and the valves are elliptical as in Cocroneis.
Specinien. no. mll72-type: Photo, no.
LM. 2199.
Both in the type species and in the
new variety, the valves seem to be double-lamelliferous. having coarsely andfinely porous membranes. The coarsely
porous membrane (probably the convex

side of the valve) provided with radiating rows of some\vhat deep. rectangularloculi about 300-2000m.u long .and 200250mtt broad ; the finely porous membrane (probably the concave side of thevalve) provided with radiating rows ofround pores about 100-200mtt in diameter.
In many valves, the finely porous membrane is completely lost.
References
DESIKACHARY. T.V. and ALEEM. A. A. (1955).
Electron microscope study of diatom wall
structure VII.. Jour. Sci. & Jndu.~t. Res.,
110/. 14 c. pp. 42-46.
DESIKACHARY, T.V. (1957). Electron microscopy and Algology. Proc. Ind . .4cad. Sci.,
vnl. 46, pp. 54-64.
GERLOrF, ]. (1957). Electroncnmikroskopische
Untersuchungen an Diatomeenschalen. I.
Dcr Bau der Schale von Guinardia ftaccida(CASTR.) PERAGALLO. Ber. De11t. Bot.
Ges., l'ol. 69. pp. 499-504.
KoLBE, R. W. (1956). Zur Deutung und Auswcrtung elektronen- mikroskopischer
Aufnahmen in der Diatomeenkunde. Bot.
Not., t•nl. 109. Fasc. 3, pp. 368-373.
MAcl\·IJLLAN. R. S. (1956. 57), Personal communications.
OJ\Ul'\0, H. (1952). Atlas of fossil diatoms
from Japanese diatomite deposits.
- - (1955-59). Electron-micro!'copical study
on fine structures of diatom frustulcs.
Xlll-XVIL Bot. i"fag. Tokyo, t·ot. 68. pp.
125-128, 1•ol. 69, pp. 186-192, l'ol. 70, pp.
]01~107. 216-222, L'O/. 72, pp. 61-67.
- - (1 9 55-58), Electron-microscopic finestructure of fossil diatoms. III- V. Trans.

Explanation of Plate ~2
Fig. 1. r1mp!wra proteus GREGORY. Valve. ( x 15000)
Fig. 2. Surire/la stria!11la TuRPIN var. bnmis (EHRENBERG) DE To:-;1. Valve; inside \·icw.
( x3000)
Fig. 3. Campy!odiscus Kiilzingii BAILEY et HARVEY. Val\•e; inside view? (x3000)
Loc. (Figs. 1-3) 15 miles south of Fallon, Churchi II County, Nevada, U.S. A.

OKUNO :Fine Structure of Fossil Diatoms

Plate 22

37 5.

Electron-1Vlicroscopic Fine Structure of Fossil Diatoms

Prnc. Pa/aeont. Soc. Japan, N.S., No. 19,
pp. 53-58, No. 21, pp. 133-139, So. 31, pp.
237-242.
- - (1956), Diatomaceous earth in Yatsukamura and Kawakami-mura. Okayama
Prefecture. ]our. ]apna. Bot., vol. 31, pp.
345-350.
- - (1958), Diatomaceous earth in Setana·cho, Hokkaido. 2. l. c .. rol. 33, pp. 193-198.
- - and KolWSAWA. K. (1957). Index of dia·
toms researched with the electron microscope. 1. Bull. Fac. Text.·Fibers. Kyoto
Uni11. Ind. Arts & Text.-Fibers. z•ol. 2. pp.
43-58.
RAPIER, P.M. (HJ55), The indomitable diatom.
Eng. & illin. ]our., vol. 156, pp. 90-93.
PA:-<TO(:SEK, J. (1903), Bcitrage zur Kcnntnis
der Fossilen Bacillarien Ungarns. 2 Auf.
PRoSCIJKINA·LAVRF::-;Ko, A. I. (1951), Freshwater diatoms.

191- - (1955). Plankton diatoms of Black Sea.
SKvoRTzov, B. (1937), Neogene diatoms hom
V{amura, Nagano Prefecture. Central
Nippon. Mem. Col/. Sci. Kyoto linp. Univ.
S~r. B. 1'01. 12. pp. 137-156.
. .
- - (1937), Neogene diatoms from Saga Prefecture. Kiushiu bland. ~ippon. l. c., vol.
12. pp. 157-17-1.
S.\IITH, W. (1853, 56). Synopsis of the British
Diatomaccae. 1. 2.
TSD!l:RA. K. (1955), A contribution to theknowledge of diatoms found in the clod
from the pond on Mt. Shichimen-Zan, inJapan. four. Yokohama !vlrm. Univ. Ser;
C-12, no. 43, pp. 1-32.
WoLJ.E, R F. (1894), Diatomaccae of North
America.
ZflliSt-:. A. P., PROSCHKIC'>A·LAVRE1"KO, A. L
and SHF:SHUKOVA·PORETZKAJA, B.. S.
(1949), Diatom Taxomony.

~ '

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PROCEEDINGS OF THE PALAEONTOLOGICAL SOCIETY
OF JAPAN

1:3 ~i~l1:~~~~ 74 IDJfYIJiw:._I959 iF IL fl 21
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.................................. I=PIR4':.::: :!llf .l:')f'l1:

llayasakaPora, a New Permian Bryozoan
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Bryozoan Genus from Fukuji. !Iida
Massif. Japan. (~iflt) .... Sumio SAKAGAMI
Brachiopoda from the Permian Maizuru
Group (1) ............ Daikichiro S11rMrzu'I'WIII!!IJ· 17 l!€ili't 7.> ifiXI4'lliiJf!(Jft:fi0~7.> b (})
It:-:>~' -c ('§!fl!ffii'J· 17 iiEI.Ii '1' 7.> {t:fijb~/lHf.!t.:"':)t '"'C. ~(}) 1) .................... ~ff Illlltli4i~llffi!G.!/I!Iwt0) ltEil'fl.: ··:n' -c .. ,M(tllli'l.::.lliM!~IIjll'fi!f'W Pectinidae .......... *~U II I'll=
Upper Cretaceous Ammonites of Califor·
nia, Part Ill. ...... Tatsuro MATSUMOTO

1'1 Ji!Hc=fl.l:fl' 0{twF1H'H: ~ (})~i! 1.:? ~ '-c.................................. ~~fJ'(;ift

Zonation of the Non-Marine Upper Meso·
zoic Wakino Subgroup ..... Yoshihisa OTA
Zur Kenntnis der Oxytominae (Lamelli·branchia) ............. Koichiro ICHII<AWA

Some Ordovician Fossils from East Tonkin. Viet-Nam ......... Teiichi KonA YASIJJ
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fecture, japan .......................... .
............ Fuyuji TAKAI and Shoji FuJII

c~lJif>;:tA:ttll~~1tllO).ff:!4. JEtf)1J".IfT................ -...... . 111~

· ·· ·· ·· ·· ·f!l! • 'Sn i't'i

Mesozoic Plants from the Yatsushiro
Formation (Albian), Kuma District, Kyushu, Japan. (ftiflt) ..... Tatsuaki KIMURA
Mesozoi'c• Plants from the Itoshiro and
the Akaiwa Sub-Groups. I. Bennettitales.
(Mesozoic Plants from the Tetori Group,
Central Honshu. Japan, Part III). (~~)...... Tatsuaki KIMURA and Shinji SEKIDO~f:ifijilli'iJ~BUIBJ7JaF~f.ftf~l£l1±1;: t '-c (ft:EEt~~(})mrwmtrdilrBWdmm;ti vn.) .. J!!l!f lfltt

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