a -!t~~±~~xr­{U..~· ;~tTransactions and Proceedingsof thePalaeontological Society of Japan
New Series

No. 59Palaeontological Society of japan

Sept. 30th, 1965

CONTENTS
TRANSACTIONS
Page

490. Carboniferous Conodonts from Yobara. Akiyoshi Limestone. japan (Studies
of Asiatic Conodonts, Part II) .......... 1-1 isayoshi IGo and Toshio KOIKE 83
491.

Some Fossil Anadara from Southwest japan ................ Hiroshi NooA 92

492.

A Gigantic Scallop from the Sea Bottom off the Danjo Islands. Nagasaki
Prefecture, japan ........................................ joji NAGASAWA 110

493. On a Lower Cretaceous Pelecypod ... Cvrena" naumanni. from japan ....
.. .. .. . .. . .. .. .. .. .. .. . .. .. .. .. .. . .. .. .. .. ltaru HAY Al\1! and !sao NAKAI 114
494. Cretaceous Echinoids from the Sanchu Graben. Central japan ........... .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Keisaku TAN AKA 126
PROCEEDINGS ................................................................ 143

President : Kiyoshi AsANo
Councillors:

Kiyoshi ASA!\0 (Editor of "Fossils"), llaruyoshi

FuJI~IOTO,

TetsuroHANAI (Editor of Transactions and Proceedings), Wataru HASIIIMOTO (Treasurer), Kotora IIATAI, lchiro HAYASAKA. Koichiro ICHIKAWA, Taro KANAYA,
Teiichi KonAYASIII, Tatsuro :MATSUMOTO (Editor for Special Papers), l\lasao
MINATO, Hiroshi OzAKI (Planning), Tokio SHIKAMA (Membership), Fuyuji
TAKAI (Chairman of Executive Councillors' Committee), Ryuzo TORIYAMA
Secretaries: Takashi HAJ\IADA. Hisayoshi IGO, Yokichi TAKAYANAGIAssistant Secretary: Takeo l<.:HIKAlVAAll Communications relating to this Journal should be addressed to the
PALAEONTOLOGICAL SOCIETY OF JAPAN
Geological Institute, Faculty of Science, University of Tokyo, japan

Trans. Proc. Palaeont. Soc. Japan. K S., No. 59. pp. 83-91, pis. 8. 9, Sept. 20, 1965

490.

CARBONIFEROUS CONODONTS FROM YOBARA.
AKIYOSHI LIMESTONE. JAPAN(STUDIES OF ASIATIC CONODONTS. PART II)*HISAYOSHI IGO and TOSHIO KOIKE
Institute of Geology and Mineralogy, Tokyo University- of Education~~~~w~-~~~~~~~: •m•-~~~L~~@m~•b~~~~~uw~~:rif$5~ ~ J F"' 1- ~~-"'. -t~llil'fi;:~~~H.. t..:, ~A':Z~I(:f'l*~ ~n~:9l;i(:f.fH!r lA..:'Wif#:tJJ;l(¥i,i!lQ) i ~ l: mtrJ.i" 7.>iJ:. .t I)"":/:/ Jl.o<.::. -\"*Q)~*n: iW
Chesterian .!: Q)mktJ<f.ttJ;;m<.

<t.t-?"tl,·7.>o li~J¥.~; ~"' t-t'f.!lfm:wiWQ).::Cit.l:t:tl~liiJH!'IL1n·. "it..:,t"'\"-'\"ii<"":/::..-Jv:.::.1"*i1fH'lll;(:J.:j'J±~:tL.t ), ~,,< l?ii'Oi!.~"?"ti Chesterian J:ii!l~ Kinkaid .t IJi!l<!·:tf.t 7.> 'H\, tt.:t->~ff'&'l?n: ~ J F ~ ~ ~i'PU!Ji!;lili L t..:~~ttiF. L t'lim@MQ)'Hf~S\I.t IJ ~-'\"<~f'l ~ 7.

.l:{l1"('!.,7.>o*' ']• it!! fit{"}(Iv1asamichi OT A of the Akiyoshidai Science Museum for his valuable suggestionin the field. \Ve also thank Mr. Tada·
hiko OGAWA for his help to our laboratory work. A part of the expenses ofthe field survey \vas defrayed from the
Scientific Research Fund, :\1inistry of
Education. japanese Government.

Introduction and Acknowledgements

The Akiyoshi Limestone is the classi·
cal field of the Upper Paleozoic strati·
graphy and paleontology in Japan andhas been repeatedly studied by many
workers. Recently YANAGIDA (l962i hasreported an interesting brachiopod faunafrom the Uzura quarry, Yobara. The
stratigraphic position of this quarry isthought to be lower part of the Akiyoshi
Limestone Group and to be equivalent
to the Millerella sp. a Zone (TORIY AMA,
1958). Also YA:VIAGIWA and OTA (1963)
have described several corals from thesame locality. V{e have succeeded toseparate well-preserved rich conodontsfrom the limestone collected from thementioned fossil locality. This paper isdealt with these conodonts and discussionof their geologic age.
Acknowledgements are due to tvir.

Conodont Fauna and its Geologic Age

The material was collected from theabandoned quarry named Uzura at Yo·
bar a, Ofuku, Yamaguchi Prefecture, south·
western Japan (Text-fig. 1). Limestone
cropped out in this quarry is highly
fossiliferous, pale gray and massive to
bedded. It abundantly yields brachia·
pods. corals. smaller foraminifera andmany other fossils. We have found thefollowing conodonts, namely :-Hindea·della sakagamii IGO and KOIKE. Synprio·
niodina sp .. Ligonodina hanaii lGO and
KOIKE, Lonchodus sp .. Lonchodina aki·
yoshiensis IGO and KOIKE, n. sp.. Lon·

* Received Jan. 5, 1965: read April 5, 1964.
at Urawa.

83

84

Hisayoshi !Go and Toshio KOIKE

Text-lig. 1. Maps showing the locality.

chodina ? sp. A, Lonchodina sp., Hindeodus imperjectus (REXROAD). Ozarkodina
orientale lGO and KOIKE, Spathognathodus
minutus (ELLrso~). Gnathodus opimus[GO and KOIKE, Gnathodus commutatus
tBRA~SON and MEIIL) nagatoensis [GOand KOIKE, n. subsp., and other fragmentary indeterminable genera.
This conodont fauna is very similar
to the Omi conodont fauna which was
described by !GO and KOIKE (1964) but
as will be discussed below there can berecognized some differences between bothfaunas. Hindeodella sakagamii, Lonchodina hanaii and Ozarkodina orientale arecommon species in both faunas. Gnatlzodus opimus and Gnathodus commutatus
nagatoensis are very abundant and characteristic species in the Akiyoshi fauna,but they are rare in the Omi. Lonchodussp., J.onchodina ? sp. A, Lonchodina sp.,
Lonchodina akiyoshiensis and Spathognathodus minutus are not so common
in this fauna, but they have never beenfound in the Omi fauna. The genera
Streptognathodzts and Idiognathodus arecharacteristic in the Omi fauna, particularly the former, but both genera havenever been obtained from the Akiyoshi
fauna. The species of Hindeodella andSynprioniodina are rather common in
the Omi fauna, but they are rare in
Akiyoshi.
The geologic age of the representing
fauna is an important problem. YANAGIDA (op. cit.) described many brachiopods from the same locality, although
the brachiopod-bearing horizon is slightly
below the conodont rich horizon. According to his extensive paleontological work,
these brachiopods are similar to those ofEuropean and Asian upper Lower Carboniferous (Visean), such as, Phricodothvris
insolita GEROGE, Brachythyris a/ziyoshiensis YANAGIDA, Spirifer aff. liangehowensis CHAO, Spirijer sp., Cleiothyridina
expansa (PHILLIPS), Cleiothyhdina royssii(L'EVEILE), .-l.ctinoconchus planosulcata(PHILLIPS), Composita aff. argentea (SHEPARD), Dielasma cfr. kingi DE KONINCK,
Dielasma sp., Yanishewskiella japonica
YANAGIDA, Pugnax aff. sulcatus (SowERBY) and Schizophoria aff. resupinata(MARTIN).
YA:I\IAGIWA and OTA (1964) described
the following corals, namely :-SiylidoPhyllum ozawae Y Al\IAGIWA and OTA,
Clisiophyllum awa (1\hNATO), Clisiophyllum sp., Lonsdaleoides toriyamai MINATO
and Lophophyllidium uzurensis Y AMAGIWA and 0TA. Although they did not4.90.

Ca;·bo·nife·rous Conodont.~ from Akiyoshi"discuss the geologic age of the coralfauna, it has close similarities to thosefrom the lower part of the !\•Iiddle Carboniferous (the Millerella to Profusulinella Zones) in southwestern japan.
As already discussed by the writers,
the Omi conodont fauna \vas thought tobe Early Pennsylvanian or Late Namurian
in age, and not younger than l\Iiddle
Pennsylvanian. The Omi conodont fauna
are lacking the typical Mississippian
genera and species. The Akiyoshi fauna
is also avoided the characteristic iVlississippian conodont genera. but some ofthe species are related to the highest
Mississippian (Chesterian) species ofNorth America. Hindeodus imPerfectus
is not so many in this fauna but it has
been repeatedly described from the
Chesterian of the upper l\lississippi
Valley region. According to COLLI.SS01\,
ScoTT and REXROAD (1962) this species
ranges up to the top of the Kinkaid
Limestone. Spathognathodus minutus isa long ranging species in the Pennsylvanian (ELLISON, 19·11. SnmGEN and
YouNGQUIST, 1949 etc.).
Ozarkodina
orientale is similar to the Chesterian
species of 0. compressa REXIWAD. Lo11·chodina akiyoshiensis resembles L. jurnishi REXROAD \Vhich was describedfrom the Glen Dean Formation of thetype Chesterian in the upper Mississippi
Valley region. Gnathodus opimus isrelated to G. roundyi \vhich has been
known from the various localities of
the Desmoinesian in North America. It
also has some similarities to Gnathodus
girtyi which was described from theMississippian Barnet Formation in Texas(HAss. 1953). The Mississippian speciesof Gnathodus texanus ROUNDY and thecosmopolitan species of G. mosquensis
PANDER are also allied species to our
specimens. Gnathodus commutatus naga.toensis resembles the several subspeciesof G. commutatus described from thelVIississippian ancl Namurian in North
America and Europe.
As mentioned above the present fauna
is consisting of both Upper Mississipian(Chesterian) and Pennsylvanian species
or allied ones. On the other hand.
entire lacking of Slreptognalhodus andJdiog11athodus is never overlooked toconsider the geologic age of this fauna.
The mentioned genera are very characteristic and prominent in the Omi Limestone. From these faunal characters webecame to conclude that the Akiyoshi
conodont fauna is slightly older than theOmi fauna and considered to be theearliest Pennsylvanian or latest Mississippian in age. There is. however.
stronger possibility of the earliest Pennsylvanian age of this fauna rather thanof the Mississippian.

Description of Species

Genus llindeodella BASSLER, 1925

Hindeodella sakagamii leo and KOIKE
Pl. 8, figs. 1. 2

Hindeodella sakagamii !Go and KoiKE, 1961.
Pal. Soc. japan, Trails. Proc., 11. s., no. 53,
p. 18<1. pI. 27. figs. 1, 2.

Comparison :-All specimens at handare quite identical to the Omi specimens
and we could not find any remarkabledifference. Further description seems to
be unnecessary.
Reg. nos. 23090. 23091.
Genus Synprioniodina ULRICH
and BASSLER, 1926

Synprioniodina sp.
Pl. 8. fig. 9

86

Hisayosll'i !GO and Toshio KoiKE

Two bars meet forming an angle ofabout 40 degrees in common plane.
Posterior bar thin, laterally compressed,
rather high and having sharply edgedaboral side. Denticles subequal in size
throughout, sharply pointed, almost erector slightly angled anteriorly. fused atbase and deeply penetrated into bar.
Anticusp short, having coalesced andanteriorly inclined denticles. 1\lain cusp
thin, sharply pointed. directed anteriorly.
Aboral side of bar distinctly grooved.
Pulp cavity beneath main cusp deep,
conical and with moderately elevatedflare.
Comparisou :-This indeterminable species resembles Synprioniodina microdenta
ELLISON, but the former has higher posterior bar and subequal posterior denticles. Synprioniodina collinsoni IGO and
KOIKE is also allied species, but thedenticles of the posterior bar and anticusp are dissimilar in shape. The
American Chesterian species of Synprioniodina denticamura REXROAD and
LIEBE is very similar to our S. sp .. but
owing to the incomplete Akiyoshi material detailed comparison is diflicult.
Reg. no. 23092.

scribed from the Early Pennsylvanian.
shale, Knoxville. Iowa.
Reg. no. 23093.
Genus Lonchodus PANI>EI<, 1856
Lonclwdus sp.
PI 8. fig. 11

Imperfect bar straight, laterally compressed, slightly curved inward andhaving very thin posterior end. Aboral
side distinctly grooved. Denticles long ..
discrete, laterally compressed, almost
erect or slightly directed posteriorly,.
having sharp edges antcro-posteriorly
and sharply pointed tip.
Comparison :-.Many similar fragmentary bars have been described and illustrated from the various Lower Pennsylvanian and Upper Mississippian rocks.
Lonc/wdus ? sp. came from Knoxville,.
Iowa (YouNGQUIST and IIEEZEt\, 19,18)
and ELLISON's (1941) indeterminablespecimen (Pl. 20, fig. 28) are similar toour specimens.
Reg. no. 23094.
Genus Lonchodina BASSLER, 1925

Genus Ligonodina BASSLER, 1925

Lonchodina ? sp. A

Ligonodina lwnaii lGO and KOIKE

PI 8. fig. 15

Pl. 8. fig. 13

Cnit consisting of two bars forming
about right angle. Anterior bar rather
long, thin, and \vith five denticles. Anterior dent ides discrete, sharply pointed,
rounded in cross section, almost erect or
curved posteriorly and inward. .lvlain
cusp not so large, circular in transverse
section. Posterior denticles large, slightly curved posteriorly, flattened and withsharp edges antcro·posteriorly. Numberof posterior denticles may be one or two.
Pulp cavity large, located beneath main

Ligonodina harwii !GO and KoiKE, 1964. Pal.
Soc. }af>arr. Trans. Proc., 11. s.. no. 53, p.

186, pl. 28. figs. 21, 22.
Comparison:- The Akiyoshi specimens
are quite identical to the Omi specimens
and no further description is necessary.
As already pointed out by IGO and KOIKE
this species resembles Ligonodina typa
(GU:\1\ELL). It also resembles Ugonodina
abbrelliala YOUNGQUIST and I IEEZEl' de·490.

Cw;·boniferoHs Conodonts from AJciyoshi·cusp. conical and rather shan·ow, surrounded by slightly expanded flare.
Aboral side of bar distinctly grooved.
Comparison :-Lonchodina ? sp. A is:similar to Lonchodina ? nipponica !GO.and KOIKE described from the Omi
Limestone, but the present indeterminable species has different main cusp andposterior denticles. It also closely resembles Lonchodina ? panderosa ELLISO.'i,
but our specimens have different shape·of the denticles. This species seems tobe new to science but denomination isreserved until more numerous materials.are accumulated.
Reg. no. 23095.
Lonchodina a!?tyoshiensis IGO

and KOIKE, n. sp.
Pl. 8, figs. 8, 10. 12, 14

Bar thin, blade-like, consisting of anterior and posterior bars meeting at anangle of 120 degrees. Anterior bar longand rather high and with sharp anterior·end. Anterior denticles six to seven in
number, laterally compressed, somewhat·curved posteriorly and most of them·equal in size, with sharp edges fore andaft and coalesced at base. Main cusp
parallel to anterior denticles and having·elevated median ridge continuing to expanded triangular flare. Posterior bar
shorter than anterior bar. Posterior·denticles variable in size and shape,
three or four in number. thin, sharply
pointed and almost erect to base of bar.
Pulp bavity large and sharrow. Aboral
side of bars with deep groove extended
from pulp cavity.

87

cusp than our form.
Reg. nos. 23096 (holotype), 23097-23099.
Genus Hindeodus REXROAD
and FURNISH, 1964
Hindeodus imperfectus (REXROAD)
Pl. 8. figs. 3-5, 7

Trichonode/la imperfeclcz REXROAD, 1957, 11/inois Geo/. Sun•. Rep. inv .. 199, p. -H.
pl. 4. figs. 4, 5: REXROAD, 1958, Ibid.,
209. p. 26, pl. 4. fig. 6.

Elsonel/a ? imperfecla REXROAD and COLLJ;>;so~. 1961, Illi11ois Geol. Sun:., Circ., 319 .
p. 6: REXROAD and BUR TO:-.:, 1961. jour.
Pal., vol. 35. p. 1152. pl. 141. fig. 1.
lli11deodus imperfectus REXROAD and FuR:"ISil, 1964. Ibid., vol. 38, p. 672. pl. 111.
figs. 13, 14.

Lateral bars in one plane or veryslightly twisted, thin and blade-like,meet at approximately 120 degrees
beneath main cusp. Aboral side of bars
slightly concave downward, sharply
edged and not grooved. Denticles inboth bars eight to nine in number andmore or less variable in size and number,and generally smaller adjacent to main
cusp and distal end. circular in crosssection and sharply pointed. whose anterior surface flat and posterior surface
convex posteriorly. Pulp cavity small,conical and shallow with faint elevationof flare on posterior side of main cusp
but depressed on opposite side.
Comparison:- The Akiyoshi specimens
are quite similar to the American Ches·
terian specimens and no remarkable dif·ference can be recognized.
Reg. nos. 23100-23103.

Comparison :-Lonchodina akiyoshiensis

resembles Lonchodina furnishi REXROAD·described from the Glen Dean Formation(Chesterian) of Illinois and others. but
the American species has larger main

Genus Ozarkodina BRAJ\SON
and :\IEHL, 1933
Ozarkodina orientale leo and KOIKE

88

Hisa.yos/l'i ]GO and Tu:;hio KOIKR
Pl. 9. figs. 14. 15

Ozarkodina orientale leo and KOIKE. 1964.
Pal. Soc. ]apa11. Trails. Proc .. 11. s .. no. 53.
p. 187. pl. 27. figs. 21-23.

Comparison :-The Akiyoshi material
is similar to the Omi specimens which\vere illustrated in Text-fig. 3 on plate2 (lGO and KOIKE, 1964). but it differsfrom the latter in weaker elevation offlaring lip and larger main cusp. The
mentioned biocharacter is closely related
to Ozarkodina compressa REXROAD described from the Kinkaid Limestone.
uppermost Chesterian in Illinois.
l~eg. nos. 23105, 23106.
Genus Spathognathodus BRA!\SON
and MEIIL. 1941

Spathognathodus minutus (ELLISON)
Pl. 9, ligs. 16-18

Spalhodus minutus Er.t.rso:-~. 1941. jour. Pal ..
vol. 15. p. 120. pl. 20. figs. 50-52.

Spathognathodus minulus ELLISO:>: and GRA·
VES, 1g,11.
Missouri Univ. Sch. Mines,
Metal/ .. Bull .. Tech. Ser .. vol. 14. no. 3.
p. 3-4, pl. 2. figs. I, 3, 5: YouNt;QutsTand Dow;-.;s, HJ49, four. Pal .. vol. 23. p.
]69-170. pl. 30, fig. 4: STURGEON and
YouNGQl:rsT. 1919. Ibid .. vol. 23, p. 385,
pl. 74, figs. 9-ll : pl. 75. fig. 19.

Blade short. thin. laterally straight andwith arched aboral side and sharply
edged anterior and posterior ends. Dcnti·
des coalesced. laterally compressed. withsharply pointed tips, variable in sizeand shape, and become smaller towardboth anterior and posterior ends. Posterior denticles chevron-like. nine to ten
in number. Anterior denticles three in
number. small in size. 1\hin cusp large,
erect to slightly directed anteriorly.
Pulp cavity near posterior end of blade,large. expanded with the deepest pointat slightly posterior of main cusp.
Aboral side of anterior part of blade
grooved.
Comparison :-Our specimens are iden·--------

Explanation of Plate 8(All figures x 75 except for fig. 6)
Figs. l. 2. Jlindeodella sakagamii lGo and KoJKE
1. inner lateral view; 2. outer lateral view.
Fig:;. 3-5, 7. Hindeodus imperjectus (REXROAD)3, 4. outer lateral views; 5. inner lateral view; 7. outer lateral view.
Fig. 6. Lonchodina sp.
6. inner lateral view. x 37.
Figs. 8. 10. 12, 14. Lonchodina akiyoshiensis leo and KoiKE. n. sp.
8, 10. outer lateral Yiews: 12, inner lateral view: 14. inner lateral dew of the hololype.
Fig. 9. Synprioniodina sp.
inner lateral view.
Fig. 11. Lonchod11s sp.
outer lateral view.
Fig. 13. Ligonodina hanaii leo and KotKE
inner lateral view.
Fig. 15. Lonchodina ? sp. A
outer lateral view.

leo and KOI KE:

Carboniferous Conodonts from Akiyoshi

Plate 8

490.

Cm·boniferous Conodonts from Aki11oshi

tical to the ELLISON's specimens andalso to other American specimens. Compared with the ELI.Jso:-;'s holotype, theJapanese specimens have slightly fewer
number of the posterior denticles.
Reg. nos. 23107-23109.
Genus Gnathodus PANDER. 1856
Gnathodus opimus lGO and KOIKE
Pl. 9. figs. 1-8Gnathodus O/Jimus !Go and KotKE. 1964. Pal.
Soc. japan, Trans. Proc .. 11. s .. no. 53. p.
189. pl. 28. figs. 15-18.

Comparison:- The Akiyoshi specimens
slightly differ from the holotype of Omi.
Species of Gnathodus arc very variablein the ornamentation and shape of cup.
Some of the Akiyoshi specimens havethree parallel node-like ridges including
carina continued from blade. The development of these ridges along carina
are very variable as illustrated in theplate. Therefore we treated these biocharacters as an intraspeci fie variability.
Gnathodus girtyi HAss has three parallelridges but our species is lacking transversely developed nodes.
Gnathodus
roundyi GUN:'\ELL is also similar to our
species.
Reg. nos. 23110-23117.
Gnathodus commutatus (BRA~SON and
1VIEHL) nagatoensis lGO and

KOIKE, n. subsp.
Pl. 9, figs. 9-13

Axis straight to slightly curved inward. Denticles of carina fused, nodelike with obtuse tip or subtriangularshape in lateral view. Cup widest inalmost middle, asymmetrical its andouterside slightly wider than inner side.

89

Height of cup gradually decrease posteriorly. Oral surface of cup smooth insome specimens or ornamented by two
low nodes adjacent to carina anteriorly
in other specimens. Blade thin. laterallycompressed, slightly longer than carina.
Denticles of blade fused. increase in size
to ncar anterior end. Each denticles has
sharp-edged tip. Aboral side of blade
sharply edged with fine groove merged
into expanded pulp cavity. Apex of
pulp cavity located at same point ofwidest part of cup.
Comparison :-This new subspecies ofGnathodus commutatus differs from othersubspecies of commutatus in the lateralview of the cup. Summit line of Gna·lhodus commutatus (s.l.) in l:ltcral viewis usually straight or substraight, but our
subspecies has arched summit line andshows narrow node-like carina on cup.
Reg. nos. 23120 (holotype) 23118. 23ll9.
References Cited
BAKER. R. C. (1942) : The age and fossilsof the Olentang~· Shale of central Ohio.
ilmer. jour. Sci .. v. 240. no. 2, p. 137-143.
pis. 1-3.
BRA<"so;-.;, E. B. and MEHL. M.G. (1941) :New and litlle known Carboniferous
conodont genera. jour. Pal .. v. 15. no. 2,
p. 97-106. pl. 19.
Cot.t.INSON. C., ScoTT. A. and REXROAD.
C. B. (1962) : Six charts showing biostartigraphic zones and correlations
based on conodonts from the Deveonianand Mississippian rocks of the upper
Mississippi valley. Illinois Ceo/. Sun• ..
Circ .. 328. p. 1-32.
Coop~:R. C. L. (1935): Conodonts from theupper and middle Arkansas no\·aculite,
Mississippian, at Caddo Gap. Arkansas.
Jour. Pal .. v. 9, no. 4. p. 307-315. pl. 27.
Et.Ltso:>:. S. (1941): Revision of Pennsrlvanian conodonts. Ibid .. \'. 15. no. 2. p.
107-143. pis. 20-23.

'90

Hisayoshi leo and To8hio KOIKE

and GrlAVES, R. W. (1941): Lower
Pennsylvanian (Dimple Limestone) conodonts of the Marathon region, Texas.
Univ. Missouri Sc/1., Min., and Met. Bull.,
Tech. Ser., v. 14. no. 3, p. 1-13, pis. 1-3.
FAY, R. 0. (1952): Catalogue of conodonts.
Kansas Univ. Pal. Contr., art 3, p. 1-206.
figs. 1-109.
GuN:-;EL. F. II. (1931): Conodonts from theFort Scott Limestone of Missouri. jour.
Pal .. v. 5, no. 3. p. 2-14-252. pl. 29.
- - (1933) : Conodonls and fish remains
from the Cherokee. Kansas City, and\Vabaunsee groups of Missouri andKansas. Ibid .. v. 7. no. 3, p. 261-297. pis.
31-33.
HArwrs. R. W. and Hol.l.ll'>GS\\'ORTII, R. V.
(1933) : New Pennsylvanian conodontsfrom Oklahoma. Amer. jour. Sci .. v. 25.
no. 147, p. 193-20·1. pl. 1..
!lAss. W. II. (1953): Conodonts of the Barnett
Formation of Texas. U.S. Ceo/. Surv ..
Prof. Paper. 243-F. p. 69-94, pis. 1-1-16.
- - (1959) : Conodonts from the Chappel
Limestone of Texas. Ibid., 29'1-J, p. 365399, pis. ·16-50.
- - . RuoDES. F. H. T. and MOLLER, K. J.
(1962) : Conodonts in Moore's Treatiseon Invertebrate Paleontology. Pt. W, p.
Wl-W97: W216-W259.
Some Namurian
IliGGI:":S. A. C. (1961) :conodonts fromNorth
Staffordshire.
Geol. Mag., v. 98, p. 210-224, pis. 10-12.
!Go. H. and KOIKE. T. (1964) : Carboniferous conodonts from the Omi Limestone,

Niigata
Prefecture.
Central].1pan(Studies of Asiatic conodonts, part 1).
Trans. Proc. Pal. Soc. japan, 11. s .. no. 53,
p. 179-193, pis. 27, 28.
REXROAD, C. B. (1957) : Conodonts from the
Chester Series in the type area ofsouthwestern Illinois.
Illinois Geol.
Surv. Rept. lnv .• 199, p. 1-43, pis. 1-·1.
- - (1958) : Conodonts from the Glen Dean
Formation (Chester) of the Illinois Basin.
Ibid .. 209, p. 1-27. pis. 1-6.
- - and Bt.:RTo:-:. R. C. (1961) : Conodontsfrom the Kinkaid Formation (Chester)in Illinois. jour. Pal.. v. 35, no. 6, p.
1143-1158. pis. 138-141.
- - and CLARK, C. E. (1960): Conodontsfrom the Glen Dean Formation of Kentucky and equivalent formations of Virginia and West Virginia. Ibid., v. 34, p.
1201-1206.
- - and CoLLINsoN, C. W. (1961) : Preliminary range chart of conodonts from the
Chester Series (Mississippian) in the
Illinois Basin. llli11ois Ceo/. Sur11. Circ.,
319. p. 1-ll. pl. 1.
- - and - - (1963) : Conodonts from the
St Louis Formation (Valmeyeran) of
Illinois, Indiana and Missouri. Ibid .. 355,
p. 1-28. pis. 1-2.
- - and Ftm~1s11, W. M. (196·1): Conodontsfrom the Pella Formation (Mississippian).
south-central Iowa. jour. Pal .• v. 38, no.
4, p. 667-676, pl. 111.
- - and ]ARRELL. M. K. (1961) : Correlationby conodonts of Golconda Group (Ches-

Explanation of Plate 9(All figures x 75)
Figs. 1-8. G11athodus opimus IGO and KoiKE
1-8, oral views.
Figs. 9-13. Gnathodus commutatus (BRA;.!SON and MEIIL) 1zagatoe11sis lGo and KotKE, n. subsp.
Figs. J.l. 15. Ozarkodi11a orie11ta/e leo and KOIKE
14. outer lateral view; 15, inner lateral view.
Figs. 16-18. Spathognathodus minutus (ELLISON)
16-18. outer lateral views.

l eo and KOIKE:

Carboniferous Conodonts from Akiyoshi

24Plate 9

3

5

7

9

12

15

4uo. Ccu·bonife·rons Conodonts fnnn A.kiyoshi
terian) in Illinois Basin. Amer. Assoc.
Pctr. Ceo[ .. Bull., v. •15, p. 2012-203-1.
- - - and LIEBE, R. M. (1962) : Conodontsfrom the Paoli and equivalent formationsin the Illinois Basin. Micropaleontology,
v. 8. p. 509-5H.
RHODES. F. H. T. (1963) : Conodonts fromthe topmost Tensleep sandstone of theeastern Big Horn Mountains, Wyoming.
jour. Pal .. v. 37, p. 401-408.
ScoTT. II. W. (19,12): Conodonts assemblages
from the Heath Formation. Montana.
Ibid .. v. 16. p. 293-301, pis. 37-40.
STA:--:I.EY. E. A. (1958): Some Mississippian
conodonts from the High Resistivity Shaleof the Nancy \Vas ton no. 1 well in north·eastern .Mississippi. Ibid .. v. 32. p. 459,176. pis. 63-68.
STAUFFER, C. and PLu~l~tER, H.]. (1932):
Texas Pennsylvanian conodonts and theirstratigraphic relations. Univ. Texas Bull.,
3201. p. 13-50. pis. 1-4.
STl1RGEO:'>l, M. T. and YoUNGQUt:>T. W. (19•19):
Allegheny conodonts from eastern Ohio.
jour. Pal .. v. 23, p. 380-386. pis. 7•1-75.
THmiPSO:"'. T. L. and GoEBEL, E. D. (1963) :Preliminary report on conodonts of the
Meramecian Stage (Upper Mississippian)from the subsurface of western Kansas.
Kansas Ceo/. Surv. Bull .. 165, p. 1-16.
ToinYA:-tA, R. (1958): Geology of Akiyoshi.
Part III. Fusulinids of Akiyoshi. Kyusltu Univ., Fac. Sci .. Mem .. Ser. D. Ceo/.,

Yobara7I

Hlv. 7, p. 1-264, pis. 1-·18.
YA:>.tAGIWA, X. and 0TA, l\1. (1963): Faunasand correlations of" Uzura" quarry, Aki·
yoshi, southwest Japan. Part 1. Akiyoshidai Sci. Mus., Bull., no. 2. p. 87-93, pls.
1-2.
YA:-;AGILJA, ]. (1962) : Carboniferous Brachiopods from Akiyoshi, southwest Japan,
Part 1. Kyushu U11iv., Fac. Sci., Mem.,ser. D. v. 12, p. 87-127, pls. 14-21.
You:w;QulsT, W. L. and DowNs. R. H. (19·19) :Additional conodonts from the PennsyJ.
vanian of lowa. jour. Pal .. v. 23. p. 161171, pis. 30-31.
- - and HEEZE~. B. C. (1948) : Some Pennsylvanian conodonts from Iowa. Ibid .. v.
22. p. 767-773, pl. 118.
- - and M11.1.ER, A. K. (19,19) : Conodontsfrom the Late Mississippian Pella bedsof south-central Iowa. Ibid., \'. 23. p. 617622, pl. 101.
- - , - - and Dow1'is, R H. (1950): Burlington conodonts from Iowa. Ibid .. v. 2·1. p.
525-530. pl. 67.
--and PATTERSO~. S.ll. (1949): Conodontsfrom the Lower Mississippian Prospect
Hill sandstone of Iowa. Ibid., v. 23. p.
57-73. pls. 15-17.
VoGEs, A. (1959) : Conodonten aus dem
Unterkarbon I und II (Gattendortia- und
Pericyclus-Stufe) des Sauerlandes. Pal.
Zeitschr., Bd. 33, no. 4. p. 266-314, Tafs.
33-35.

Ofuku}~

Trans. Proc. Palaeonl. Soc. Japan. N. S .. 1\o. 59. pp. 92-109. pis. lO.ll. Sepl. 30. 1965

491.

SOME FOSSIL ANAIJARA FROM SOUTHWEST JAPAN*
HIROSHI NODA
Institute of Geology and Paleontology, Faculty of Science.
Tohoku University, Sendai, japanl!§'iWB;4·:d)it.:W.f!l! Anadara 1(."?~·-c: Anadara takaoensis. Anadara tricenicosla.
A11adara suzukii -a-1!;->'>-c Anadara suzukii group l: L,.:t~·VctLd)~\:lqll0:711ii'U::q)~~;J~L,JH:o::> group r::f•n 7 Ni~;lef(L,f.::o 7 f;i!d) 5 ~... ~i!Etli I. ~if!J!3 a-13tr.
'If EE t'& l"lments on their characters. Ilowever.
since some problems concerning themseem to exist, the writer made an attempt
to interpret the stratigraphic rangesof those species and to correlate theAnadara (Scapharca) suzukii group withother related species which are associated with above group of Arcids from
Formosa, Okinawa and japan. Basedupon the abundant specimens of thegroup now stored in the Institute of Geology and Paleontology. Tohoku Universit v, Sendai from the various localities
di;tributed in Formosa, Okinawa Islandand japan, the present study was undertaken. This article is the outgrowth ofpart of the study on the japanese Arcidae, fossil and Recent. The other groupor groups of Anadara will be reserved
for another opportunity.

Introduction
The younger Neogene deposits of japan
are characterized by two marine faunas:
the Oyashio type or Onma-Manganzi
Fauna of OTUKA (1936) and the Kuroshio-type or Kakegawa Fauna of MAKI·
YAMA (1927). These two types of fauna
are also w·en shown in the species or the
Genus Anadara. The Anadara (Scapharca) suzukii group is restricted to andis characteristic of the latter type of
fauna whereas the Anadara (Anadara)
amicula and Anadara (ilnadara) talllllO·
kutiensis group are significant to theformer type of fauna. The present article treats the Jlnadara (Scapharca) suzukii group.
In 1926, YOKOY A~fA (1926a. p. 368) described Area suzukii from the Tonohama
Formation in Kochi Prefecture and in1928 YoKOY A~! A (1928, p. 103) recorded
and illustrated Area philippiana from theupper part of the Byoritsu Formation in
Formosa.
Recently. those two species of YoKOYAMA were included into the synonymy
of Anadara (Scaplwrca) tricenicosla by
MAKIY AMA {1958, pl. 54) without com-

Acknowledgement
The writer takes this opportunity to
express his deep gratitude to Professor
Kotora HATAI of the Institute of Geology and Paleontology. Tohoku University
who first introduced him to the study ofthis interesting group of marine pelecypods, for his untiring and sincere encouragement throughout the course of* Received Jan. 2·1. 1965: read jan. 2•1. 1965
at the annual meeting of the society. at Tokyo.

92

491.

.4. nctda,ra .(TMn Southwest Japan

this study. Deep appreciation is due to
Dr. Shozo HAYASAKA of the same institute for his contiguous guidance and discussions on the chronology of the Pacificside of japan based upon the molluscan
fossils. Acknowledgements are due to Dr.
Koichiro MASUDA of the Department of
Geology, Faculty of Education, Tohoku
University, for his kind suggestions. Mr.
Tunyow HUANG of the Chinese Petroleum
Corporation, Formosa for his kind information concerning the biostratigraphy
and details of the fossil localities ofArcids in Formosa, l\ir. Hiroo NATORJ of
Geology and Paleontology, Tohoku University for his kind offer of the specimens which he collected from the Miyazaki Basin, 1vlr. Yasuhide Iw ASAKJ of
the Institute of Geology, Tokyo University for his kind discussions on thestratigraphy and taxonomy of the Genus
Anadara in japan and to Dr. Tamotsu
MATSU:'\AGA, Chief of the Ariake Fishery Research Laboratory, Yanagawa City.
Fukuoka Prefecture for his kind donationof Arcid specimens displaying a growthseries from the Ariake Sea.
Remarks on the Anadara (Scaplwrca)
suzukii group
The Anadara (ScajJ/wrca) suzukii groupin this article includes Anadara (Scapharca) tricenicosta (=Scapharca philippiana) and Anadara (Scapharca) suzukii
both of which were reported by YOKOYAMA (1926a. 1928) from the Tonohama
Formation in Kochi Prefecture and Anadara (Scapharca) takaoensis of Y ABE andHATAI (1942) from the Nakoshi Sandstoneof Okinawa Island, a stratigraphic unit
defined by MAcNEIL (1960). These three
species resemble one another very close·
ly morphologically and are thus considered to be related with each other. Ana-

93

dara (Scapharca\ tricenicosta occurredabundantly from the Tokazan Formationin Formosa and Naganuma Formation in
Kanagawa Prefecture. As living, thisspecies is distributed in the southwestern
Sea of Japan, around the Ryukyu Islands.
Formosa. the Chinese Sea and in the
Indo-Pacific Ocean.
Anadara (Scapharca) suzukii is known
to occur from the Takanabe Formation
in !\·tiyazaki Prefecture. Ananai Formation in Kochi Prefecture. Dainichi Formation in Shizuoka Prefecture and fromthe Nakoshi Sandstone in Okinawa Island.
Anadara (Scap/wrca) takaoensis is originally from the Kaizan Bed in Formosaand is also recorded from the 1\akoshi
Sandstone in Okinawa Island.
The Tokazan Formation in the north·ern part of Formosa is underlain with
the Takuran Formation which yielded
Pecten (Notovola)javanus MARTIN. Pecten(Notovola) 11aganumanus YOKOY A?.! A, Conclwcele nipponica (Y ABE and NoMURA)
and consists mainly of sandstone andconglomerate. It is distinguished into the
Kozan and Kaenzan facies according to
the prevalence of sandstone or conglomerate. The Kozan facies is chiefly ofloose silty sandstone with intercalated
clayey sbale, conglomerate, pyrite nodules.
carbonized drift woods. ree~ limestones
and has yielded mammals. mollusks, echinoids and foraminifers. Most of thespecies of the molluscan fossils from the
Kozan facies have been described by
YOKOYAMA (1928) and NOMURA (1933)
as representing the Byoritsu Bed. Amongthem. some interesting Arcids such as
Anadara (Scapharca) tricenicosta, Anaclara (Tosarca) sedanensis, Tricidos lliyonoi, Hawaiarca uwaensis and Striarca
interplicata (=Striarca yokoyamai) are
known from this facies. Recently, SHUTO(1961) from the results of his palaeontological studies of the Miyazaki Group inHiroshi NOD.-1
Kyushu. southwestern Japan, correlated
the Byoritsu Bed (=Kozan facies of·CHAKG. 1958) to his Amussiopecten praesignis-Granulifusus dualis Zonule (=his
4th to 6th horizon of the Miyazaki Group)
based upon the characteristic molluscan
fossils.
Furthermore, SHUTO (1961) extended
his study on the molluscan fossils to.correlate the formations of Pliocene age
distributed along the Pacific borderland-of southwestern japan listing the species
in common from the isolated area as
Indonesia, Formosa, Okinawa . .Miyazaki,
Kochi, Kakegawa and the Kwanto
regions.
In 1961. TsucHI from his studies on
the fossil molluscs independently arrived
to the same conclusion as SHUTO. The
results of their works have been accepted in general by many paleontologist inJapan.
Considering the mammal fossils. Stegodun sinensis, Stegodon orienlalis. f'arelephas trogontherii, Elephas sp .. Rhincoceros sp., Cenms (Sika) taiouanus. Cervus(Deperetia) kazuseusis and Bibos geron
have been reported by RIN (1935) and·CHANG (1958) from the facies transitional
to the Kaenzan from the Kazan. The
same facies has yielded abundant marine
fossils as above mentioned, and the
mammal yielding horizon is associatedwith Anadara (Tegillarca) granosa (LINNAEUS). Those mammal fossils arc ac-cording to TAKA! (1963). commonly
known from the Pleistocene sediments
in japan.
To make a comprehensive study on
the fossil molluscs, another problem
arises as to whether Tokazan Formationis Pliocene or PleisLOcene. ?.·lany of the
mo\lusc::n fossils, particularly the important ones from the so-called Byoritsu
Bed arc characteristic Pliocene forms as
already pointed out by YOKOYAi\IA (1928),

NOMURA (1933), NO:I.IURA (1937). S!IUTO(1961) and Tsuc111 (1961), but on theother hand most of the fossil mammals
indicate the Pleistocene age, and it isinteresting that they are from the upper
part of the Tokazan Formation. In 1958,
CHANG summarized the stratigraphy ofFormosa and he stated that the Tokazan
Formation can be divided into two faciesof the Kozan and Kaenzan based on thecharacteristic lithology and he pointed
out that the former facies occupies aposition somewhat lower than of thelatter stratigraphically. He also statedthat the former is superposed \Vith discontinuity or merges into the facies of
the upper part of the Kaenzan. l'vloreover, CHANG considered that the lower
Tokazan Formation may be Pliocene
whereas the upper is Pleistocene based
upon the paleontological evidence. Thisview was previously held by OTUKA in
1935 even though he did not express astrong opinion at that time. This problem on the boundary between the Pliocene and Pleistocene is reserved for another opportunity. Without solving thisproblem, one cannot expect to undertake
correlation of strata on a widespread
scale as along the southwestern borderland of the Pacific Ocean.
The Nakoshi Sandstone \vhich yielded
Anadara (Scapharca) takaoensis, .4nadara(Scapharca) suzul?ii and Anadara (Tosarca) sedanensis in the northwestern partof the Okinawa Island was well describedby ~1ACNEIL (1960). This stratigraphic
unit overlies the Shimajiri group withunconformity and is covered with Naha
Limestone. a unit that was once considered to be equivalent with the Ryukyu
Limestone by 1-IANZAW A (1935). This
sandstone yielded abundant marine molluscan fossils as already reported by
NOMURA and ZINBO (1936), Y ABE and
HAT At (1942) whom believed it to be the491.

A.nadam front Southwest Japa·n

Shimajiri Bed of IIANZAW A (1935) and of
l'viAcNEJL (1960)
Anadara (Scapharca)
talwoensis from the Nakoshi Sandstone
is associated with Anadara (Scapharca)
suzukii. These two species closely re·sembles Anadara (Scapharca) tricenicostain surface sculpture except for the number of radial ribs and size. as will be
discussed later.
The younger Neogene formations distributed along the Pacific borderland ofsouthwest Japan are developed in the
Miyazaki Basin of eastern Kyushu, thesouthwestern part of Kochi Prefectureand from the Kakegawa district in Shizuoka Prefecture northwards to the
Kwanto region. These Neogene deposits
are represented by the Takanabe, Ananai
and Dainichi Formations respectively. andhave yielded some extinct Anadara species which are only restricted to thisarea. These younger strata (Pliocene)
are aligned parallel to the lvledian Linealready mentioned by OTUKA (1931).
The molluscan fossils from the Takanabe Formalion were studied by YoKO·
YAJI.IA (1928a). 0TUKA (1930), ITOIGAWA(1953) and SmmJ (1952-1964). In addition to the molluscan fossils. OTUKA(1932) reported Stegodon from the Takanabe Formation: This mammal is generally accepted as an index fossil of the
Pliocene age and its name is Stegodonbombifrons according to TAKA! (1963).
0TUKA \ 1931) and SHUTO (1958! expressed
the ,·iew that this elephant horizon is of
Pliocene age. SHUTO (1961) summarized
the biostratigraphy of the ~liyazaki Basinand established faunal zonules. and among
them his 4th to 6th were stated to be
Pliocene in age. Lithologically, the thickmedium grained sandstone of the lower
part of the Takanabe Formation grades
downwards inlO a tuff bed which issuperposed on a homogenous massive
mudstone which is correlated with the95

I\liocene Tsuma Formation. OTUK A (1930)
considered the relation between his Taka·nabe Formation and Tsuma Formation
to be an unconformity that is indicatedby the lithofacies and general geostructure which had been influenced by anepeirogenetic movement, probably concerned with the movement of the 1'vledianLine. Such stratigraphic relationship is
also observed in Kochi Prefecture where
the Ananai Formation lies upon the ~o­bori or Nahari Formations with clinounconformity. and where the Kakegawa
Group overlies on the Sagara Group withunconformity. Generally, the Japanesel\liocene can be distinguished from theearly Pliocene by several important features as already pointed by HAT AI (1960).
"Almost everywhere as known at pre·sent, there exsists a stratigraphical break
between the two (Miocene and Pliocene)or evidence for diastrophism when therelation is conformable. Frequently, volcanic activity accompanies the sediments
superposed upon the unconformity or associated with eustatic movement. whether
the sediments are terrestrial, brackish or
marine, while immediately below it or
the uppermost limit of the late tvliocene
evidences for regression can be often recognized but without intense volcanism".
The same relation from faunal consideration was attained by SIIUTO (1961) and
TsliCHI (1961). Further significant works
on the problem are the Umbonidae by
SUZUKI (193-l), SUGIYA~IA (1935. 1935a)
and 1\·lAKJYAMA (192·1). on the phylogeny
and evolution of the Turritella by KoTAKA (1969), on the Pectinidae by l\IASUDA(1962). Siphon alia by l'viAKIY MIA (1941}and on the Veneridae by SIIUTO (1957).
The results of studies on those fossils
clarified their geological ranges and relationship with the different strata inwhich they occur. The examined Ana·dara species show chronological ranges

Hiroshi NODA.

'96

oz
til
ll)

fQ

3

<(

- 0~
6 zo:

(!)

~

0

<(
<(

0>

ell

.....

<t

Ul

~

~

~

:;;:: <t
,.::

<(

<t <t

~

~

Ill

~

wj
~

0

~

..I
(ij

<(ILJ

Ill I..I

<t

oct

~

z
<t
z

II)

0

0

0

:r

;n

-

0:

-X 0 0<(z<tz

en .....
..... .....
~
_;

-~
<(

~

"

<(

~

-

::E

m

-

~

0

z

<t

:r
a.
a:
<(

0

lJ..

0

.....

.....

Ill

.....
<(

0

z

~

<(

0

Ill
ILl

lJ..

0

N
<(

ILl

0
1-

0
Ill
::::>
..I
..I

z
<t

:E

z

0>

:r

-

z
0
<t

Ill

Ill
0

X:

II)

0

<t
z

0

lJ..

0

z

~

lJ..
~

(J)

c:o

ll)

0>

0

-

0:

0

z
<t

lJ..

0

::E

ci
:r

~

I

0

C/)

z z

<t 0
!!:! N
0 <t .....
<t
<t
:E
lJ..

z
<t

N

0

"

-

"

0 0:
1- 0

w lJ..

:r
.....

i
0

lJ..

z
<t

0:

::::>

0
Q.

::::>

ILIO

~..I

:ra:

ILl

lJ..

O::i

0
0

zO

0

j:::~

3

1-0

"~ 0~

(998 I)YOON

3N 0 Z
1111nzns
YtiYOYNV(8981)
Vl4VJ.Ol4

3NOZ

Ytl83t13.lt13d
V13.Lltltln.L

il961lYOnsvw(196l)O.LnHS

3NOZ SINOISiVtld
N3J.03d01S90W't'

f---t19 e (JOJ.nHs3NO Z
YONVd V10tl't'Oiti3N31\(19 81)OJ.nHs3NO Z
Sll\11030 YI1VN0Hdl9( •c:6J)

3NOZ
3SN31H:>nsans

3NOZ
wnOIJ.SAW

WniN08Wn

Wn1N08Wllj't'W't'All4YW

H

z

.....

:E

<(

LL

::::>

0

~

X:

<0

ILl

(J)

t:

a:

0:

0

z

0

<(

0

-_j

-

z

.....

~

<t

::::>

::::>
:r
.....
Ill

~

;{

5?
ILl

~

<(

ILl

i

0:

- .....0

:£

0

z
z

z

~ ~

<(

0

<(

6~
Q! -

Ill

<(
II)

<(

~

N

z

<(

j:::

'S ct:l
<t

0

z

0

i1<t
-0> N.

0~---eII)
II)
0

z

ll)

ll)

::::>

t'"

II)

.....

given in the Table 1 in comparison withother groups.
An examination was made on the
Arcid specimens of the Anadara groupcollected from the Tokazan. Nakoshi,
Takanabe. Ananai and Dainichi Formations.
Measurements were made on
those specimens as shown in Figure 1.

a:
a:

z

0

:r

Ill

w

L
Fig. l. Key to symbols used in descriptions of Anadara species based on Anadara(Scapharca) tricanicosta (1\YsT). Recent.
AS:
B:
B1 :

B2 :
I-I:
L:
LH:
LL:
PA:

..I

m

~
w

..I

PS:
SA:
UA:

Anterior muscle scar
Beak
Position of beak from anterior end ofligament, defined as beak/ligament
lengthPosition of beak from anterior end ofshell. defined as beakjshell length
Shell height
Shell length
Height of ligament
Length of ligament
Angle between hinge line and posterior end of shell
Posterior muscle scar
Angle between anterior and posterior
ends of shell
Umbonal angle

IL~!'vleasurements were made on 18 individuals of Anadara (Scapharca) suzukii
from the Ananai Formation and four
from the Dainichi Fossil Zone. Seventy

491.

Anadctnt /I'O'In Southwest Japa.n

individuals of Anadara (Scaplwrca) tri·
cenicosta from the Tokazan Formationand eight Recent specimens from Waka·
noura Bay. \\Takayama Prefecture andfrom the coast of Tateyama, Chiba Pre·
fecture were examined in detail. The
details of 11 individuals of Anadara(Scapharca) takaoensis from the Nakoshi
Sandstone. Okinawa Island were alsostudied. The statistical treatments ofthe specimens above mentioned areshown in Figs. 2-'J.
Judging from Fig. 2 and 3. some dif·

~J7

ferenccs is recognized between the speci·
mens of Anadara (Scapharca) tricenicosla
mainly from Formos.a and of Anadara(ScajJ/zarca) suzukii from the JapaneseIslands.
Recently, tviAKTYAl\·IA (1958)
placed Area suzukii of YOKOYA:\IA in
the synonymy of :lnadara (Scapharca)
tricenicosta. The name of Anadara
philippiana suzukii was llrst used by
MAKIY Al\IA and SAKA:\IOTO (19551 forthe specimens derived from the Nango
sandstone and mudstone alternation beds.
Kakegawa district. Tsucm (1961) used

21

r

20

Cl)

...J 15

<t
::>
0

>
0
z
1.1.

10

10

10

0

a:;

w

(J)

~
;:)

5

z

(B) 25NUMBEROF.

RADIAL RIBS

Fig. 2. The relation between the number of radial ribs in the different species: (A).
Anadm·a (Scapharca) lricenicosla (~YsT), (B). Anadara (Scapharca) sllzukii (YoKOYA1\IA),(C). Anadara (Scapharca) takaoensis (No~ll'RA).

~l8

Hiroshi ..ll.lODA

~

10

0

~

311.
10

20

30

40

60

110

LENOTt-4 in mm. ------il>(Anodora tokooensis}

HEIGHT OF LIGAME~T' &HELL HEIGHT
60

1••

40

.

30

.E

20

:J:
~

10

,_

.

/

.

::':-..r:i..:: ...
,:l"

~t
5 201

"'

:J:

I&

10

20

30

40

60

so

70

80

LENGTH In mm. ---~

;

~

10
&

,-n ll..-n~-l~~--~~~~~~~~~-~~~~~~~~;~~~(An odor a t r icenicost a}

HEIGHT, LENGTH

Fig. 4. Figures showing the different
statistical relations observed in Anadara(Scapharca) tricenicosta (Ni'ST).

40

r
•
li

30
20

.E

,_

:J:

0

~

10

/

·.·

20
LENGTH

30

40

50

60

In"'"'·----+(Anodora suzuki! )Fig. 3. The size \·ariation in each species and the angle between the height andlength of the shells.

the name of Anadara tricenicosta suzukii
for the specimens yielded from the Taka·nabe Formation and his I~echienjian stage.
Both names may be safely considered as
homonyms. Difference between them issize; Anadara (Scaphm·ca) tricenicosta
from the Toi<azan Formation has a maxi·
mum length of 70 mm. and height of 48mm., while ilnadara (Scapharca) suzukii

from Japan shows a maximum length of
49 mm. and height 35 mm. This seems
to be an example of size increase withthe lapse of time. SCHENCK and REIN·
HART (1938) mentioned that the increasein size of the adult specimens is doubt·
less too indefinite to have exact timevalue, but a trend from small to large
is nevertheless an hypothesis worth test·
ing. Besides the difference in size ofthe shells, as noticed from Fig. 2, thenumber of radial ribs are different. Thisis a very important specific characterand generally employed in the distinctionof the species of the genus Anadara.
Most common number of radial ribs ofAnadara (Scap/wrca) tricenicosta fromthe Tokazan Formation is 28, whereas

491.

Anaclara .from Sou.th·west Japanin the japanese species of Anadara(Scapharca) suzukii the number is 24.
This difference is very important one.
Some Recent specimens from Wakanoura
Bay and the coast of Tateyama have27-28 radial ribs and in this respect they
are allied to the Formosan specimens. It
may be added that they are also related
therewith in size variation.
Accordingly, the Tokazan species isclosely allied to the Recent one fromjapan, though there are some differencescompared with Anadara \Scapharca)
suzukii. As ScHENCK and REI:'IIHART(1938) pointed out the number of radialribs is the same from the immature to
the adult or gerontic form in the Recent
Anadara bisenensis (1938. p. 15. table 10)
studied by them. The similar feature isobserved on Anadara (Scapharca) subcrena/a from the Ariake Sea. Fukuoka
Prefecture as shown in Table 2. This isshown by the series of growth stages ofthe specimens cultured by the Ariake
Fishery Laboratory, Yanagawa City, Fukuoka Prefecture.
......

.....

" ·'.....radial ribsji 2HI 30 3lj 32 33 341

age

Number of-....____

--

I

-~

6 months

9 months

431_ j_ _

1-Il year

2'

Total

3

Percentage

,6.

2

, lr

-~-:

Fossils fromvarious localities

I-·-- -~

7 12;
1·1,14.9]25.

2

1

-

2

=
1

'=1

other species of this group, resembles
the above mentioned two species. andwas originally described by Nol\WRA(1933) from the Kaizan Bed of Formosa.
The type species of NOJ\IURA is unfortunately not well preserved, but YABE
and HAT AI (1942) illustrated a well preserved specimens of that species fromthe Shimajiri bed ( = Nakoshi Sandstoneof MACNEIL, 1960) in Okinawa Island inassociation with Anadara (Scapharca\
suzullii and !lnadara (Tosarca) sedanensis. The Kaizan species is said to be
upper l\,liocene in age by No:-.wRA (1933).
Statistic measurements were made only
on a few specimens, therefore Figs. 2. 3
are shown for comparison with the otherspecies of this group. The angle ofheight against length show some difference between Anadara (Scapharca) takaoensis and Anadara (Scapharca) lricenicosta. This shows the development fromthe actina! form to the prosoclinal one,and the arrangement corresponds withontogeny. So far as known. Anadara(Scapharca) takaoensis has its lower
limit in the Kaizan bed of Formosa andits upper limit in the Nakoshi Sandstone .
Anadara (Scaplzarca) suz11kii is restricted
to the Nakoshi-Takanabe-Ananai-Dainichi
Formation and Anadara (Scapharca) lricenicosta ranges from the Tokazan Formation up to the Recent. From thelower horizon to the upper horizon. theradial ribs increase from 24 to 27--28 in
number.

E

1-6134. 1 i7.l 2.1

Table 2.

As above mentioned, the number ofradial ribs is nearly constant from thejuvenile stage to the adult.
Anadara (Scapharca) takaoensi.~. an-

Systematic De11cription

Family Arcidae
Subfamily Anadarinae REINHART. 1935
Genus Anadara GRAY, 1847
Subgenus Scaphm·ca GRAY, 1847

Hiroshi NO!Jil100.4 nadaaa (Scaplwrca) suzukii(YOKOYA~!A),1926

Pl. 10. Figs. 3-7. 10-13; Pl. 11, Figs. 9-10
1926. Area suzukii YoKOYA~H. jour. Fac. Sci ..
Imp. Univ. Tokyo, Sec. 2. Vol. 1, p. 368,
pl. 42. figs. 6-7.

The present species was originally described by YOKOYi\:\IA in 1926a on thespecimens from the Tonohama Formationin Kochi Prefecture. The original description is "Shell rather small, thick,convex, transversely oblong. inequilateral,the posterior side being somewhat lessthan twice the anterior, rounded both infront and behind. with ventral borderbroadly arched and passing gradually
into the anterior as well as to the posterior without forming any marked angle ;antero-dorsal and postero-dorsal borders
straight and forming with the anteriorborder as well as with the posterior anangle which is greater than a right angle.
Surface radiately ribbed; ribs twentyfour in number, elevated. flat-topped
with interstices varying in breadth.
sometimes broader, sometimes narrower
than the ribs themselves, crossed byprominent lines of growth which in theinterstices are elevated like lamellae
while on the ribs they are more liketransverse striae or crenulations. Beaks
more or less swollen with ends pointed
and incurved, rather approaching eachother. Area narrow. with unequal striations parallel to the hinge line. Teeth
small, nearly forty in number. A rightand a left valve. The former is 20.3
millim. long, .13.7 millim. high and 6
millim. deep, while the latter is 25.5
millim. long, 18.7 millim. high and 8
millim. deep."Remarks: Area suzukii of YOKOYA\IA~1926a) as already discussed in earlier

pages was included into the synonymyof the Recent Anadara (Scaphaaca) tricenicosta (NYST) by !VIAKIYAMA in 1958.
Three years later SrrUTO (1961) recorded
Anadara (Scaplwrca) suzukii (Yor<O·
YAJ\IA) from the Takanabe Formation in
Miyazaki Prefecture under the name of
A.nadara tricenicosta (NYST) whereas
TsucHI (1961) listed Anadara (Scaplwrca)
tricenicosta suzukii (YOKOYAMA) fromthe Takanabe Formation and his Kechi·
enjian stage. A.nadara (Scapharca) su·
zukii (YoKOY Ai\IA) resembles Anadara(Scapltara) tricenicosta (NYST) in surface
sculpture, however, as already mentioned,
YoKOYAMA stated this species to have 24
radial ribs which are elevated and flat·
topped. their interspaces are sculptured
with elevated like lamellae and on theribs there appear like transverse striae
or crenulations. These characters arealso observed in A nadara (Scaplwrca)
triceuicosta (NYST). but the number ofradial ribs are most commonly 27-28.
These features are shown in Figs. 2-3.
Anadara (Scapharca) takaoensis (No·
MURA) also resembles the present species
but the latter differs from the former inhaving stronger radial ribs and slightly
depressed posterior side. Anadara (Scapharca) suzukii (YOKOYAMA) has a moreswollen shell, and the central ventral
margin is more convex than in .4nadara(Scaphara) takaoe1z.~is (No~WRA). Ana·dara (Scapharca ?) sp. in this article isallied to A.nadara (Scapharca) suzukii(YOKOY Ai\IA) in number of radial ribs
but the former has a more elongatedform and the depressed area extends
from the beak to posterior side.
Locality and Formation: IGPS coli.
cat. no. 5"1606. Tonohama, Yasuda·mura.
Aki-gun, IGPS coli. cat. no. 54605, logi,
Iogi-mura, Aki-gun, IGPS coli. cat. no.
54607, Oono, Tano-mura. Aki-gun, all in
Kochi Prefecture, Ananai Formation,

4!JI.

ilnadara fron~ Southu·est Japa.n

Pliocene; IGPS coil. cat. no. 29244, Tombe, Kitaogasa-mura, Ogasa-gun, Shizuoka
Prefecture. Dainichi Formation, Pliocene;
Nakoshi Sandstone. Okinawa Island, Pliocene; Takanabe Formation, !vliyazaki
Prefecture, Pliocene: Nango sandstone
and mudstone alternation, Shizuoka Prefecture, Pliocene.
Anadara (Scaplwrca) takaoensis(NOMURA), 1933
Pl. 10, Fig. 14 ; Pl. 11. Figs. 3-6

1933. Area (Area) takaoensis No:-.II.JRA. Sci.
Rep., Tohoku Imp. Univ., 2nd Ser., Vol.
16. No. 1, p. 39, pl. 4, figs. 2-5.
19-12. Anadara (Scapharca) takaoensis. YABE
and l-IATAI. japan. jour. Geol. Geogr ..
Vol. 18. Nos. 1-2, p. 73-74, pl. 7, figs.
2. 3, 6.

The present species was originally described by NoMURA in 1933 based upon
the specimens from the Kaizan Beds in
Formosa. He gave the following de.scription: "Shell small. longly-ovate,
moderately inflated with rather low beak.at the anterior third of shell-length; anterior end rounded, the posterior subtruncated and somewhat produced; valve
with about twenty five distinct radialribs which are separated by much narrow interspaces; anterior ribs narrowQr
than the posterior, finely granulated.
Hinge line rather short ; cardinal area
narrow. Teeth and other internal characters not exposed. Five isolated left
valves were examined.
A specimen-chosen as the type is 23.5 mm. long, 16.0
mm. high and about 7 mm. deep."Remarks: The present species was·originally described based on the specimens from the Kaizan Beds above mentioned and subsequently YABE and HAT AI(1942) \veil illustrated this species from.the Nakoshi Sandstone in Okinawa Island.

101This species is characterized by its radialribs which are largely elevated. rather
wide and granulated on their back.
NOMURA (1933) ·stated that there are no
species of fossil as well as Recent Area
in Japan that are closely related to thisspecies but Anadara (Scapharca) suzukii(YoKOYAMA) is closely allied to Anadara(ScajJharca) takaoe11.~is (NOMURA) in its
shell surface sculptures.
Locality and Formation :-IGPS coli.
cat. no. 37428. 3HH, type locality. NNWof Shinsui Police Box, Shinsui. Enshusho.
Takao-shu, Formosa, Kaizan Beds. Miocene: lGPS coli. cat. no. 61387. Yard of
the Nakoshi Primary School, Hanejimura, Kunigami-gun. Okinawa Island.
Nakoshi Sandstone, Pliocene; IGPS coli.
cat. no. 51306. Gabesoga. Kunigami-gun,
Okinawa Island, Nakoshi Sandstone. Pliocene.
Anadara (Scapharca ?) sp.
Pl. 10. Figs. 8-9

Shell moderate in size, inflated. test
rather thick. stout. roundly quadrate .
Inequilateral, longer than high, posterior
end produced subtrapezoidal with posterior ridge. Anterior dorsal margin
shorter than posterior one, and bothnearly straight. Posterior end truncated,
forming about 122-120' with hinge line.
Anterior end smoothly rounded. Ventral
margin widely arcuated. Umbo somewhat swollen. beak small, low, turned
anteriorly, situated at about one third ofshell-length from anterior. Ligamenta!
area with 1 to 1 1/2 imperfect v-shaped
chevrons; narrow hinge line straight,
with numerous perpendicular teeth but
details unknown. Inner surface rathersmooth but \vith crenulations on ventral
margin corresponding to outer surface
with radial ribs. Shell surface with 20-

Hiroshi 1\lODA

102

21 radial ribs. Radial ribs rather sub·quadrate in cross section. flat-topped,
somewhat wider than interspaces. Inter·spaces sculptured with faint concentric
growth lines. Posterior depressed arearuns from beak to posterior ventral end.
sculptured there with 5-6 radial ribs.
Remarks: The present species is notwell preserved and therefore its precise
details could not be studied. However,it may represent a new species. It ischaracteristic in its few number andshape of radial ribs with a depressedarea along the posterior border. This
unnamed species resembles Anadara(Tegillarca) granosa (LINNAEUS) in having 16-20 characteristic radial ribs but
differs therefrom in the depressed areaand surface sculptures.
Locality and Formation: IGPS coli.
cat. no. 90033, Tonohama, Yasuda-mura,
Aki-gun, Kochi Prefecture, Ananai Formation, Pliocene.

Anadara (Scapharca) tricenicosta(NYST), 1848
Pl. 10, Figs. 1-2. 16-17
1844. llrca radiata REEVE (non SOWERBY),
Conch. Icon., Vol. 2. Area, pl. 6, fig. 40.
1848. Area tricenicosta NYST, Mem. Acad. Ro1'.
Belg .. l'ol. 22, p. 74.
1882. Scapha rca Philippiana DU!'KER. b1d.
Moll. Mar. japan., p. 235.
1891. Area- (Scapharca) philippiana, Ko1JEL T
in MARTI=" und CHEMI"ITZ, Conch. Cab.,
Vol. 8, p. 90-91. pl. 25, figs. 1-2.
1928. Area (Scap/wrca) phi/ippimw, YoKO·
YAMA, Imp. Ceo/. Sun•. japan, Rep.
No. 101, p. 103. pl. 17. ligs. 4-5.
1932. Anadara (Scapharca) tricenicosta, PR.\·
SHAD, Lamellibranchia of the Siboga
Expedition, Part 2, p. 39-40.
1933. Area (.4rca) phi/ippiana, NoMURA, Sci.
Rep., Tohoku Imp. Uni11., 2nd Ser., Vol.
16, No. 1, p. 36-37.

1954. Anadara (Di/uvarca) tricenicosla, KIRA.
Illust. Shells faPa11, Hoikusha, p. 87. pl.
43, fig. It.

Remarks: PRASHAD (1932) pointed outthat in view of the name Area radiata
having been used by SoWERBY in 1840·
for a fossil species. NYST changed thename of REEVE's species to Area triceni·
costa in 1848. DUNKER proposed thename of Scapharca philippiana for thesame species. KOBEL T (1891) described
this species in detail and published afigure of one of DUNKER's original Scapharca philipjJiana. In 1844. REEVE described Area radiata as follows: .. Shellovately oblong, equivalve, side rounded,
whitish. stained with light brown about
the umbones. sparingly covered withepiderms. radiating ribbed, ribs about
thirty in number. very narrow, obsolete·
ly rounded, interspaces between the ribs
latticed, area of ligament middling."'
KoBEL T (1891) gave a supplementary
description to REEVE's one. According
to KOBEL T (1891), this species is characterized by the shell being inequilateral,inequivalve with 30 radial ribs: radialribs rather narrower than inlerspaces
and fine lamellae form growth lines.
Ligamenta) area elongated, rhomboidal
and measures 72 in length, 50 in heightand 43 in width in mm. As pointed out
by KOBEL T (1891). REEVE's description
was based only upon the shell surface.
·while KoBEI.T's description included thesurface and inner shell. It is importantthat KOBEL T mentioned that the shell of
this species is inequivalve and that there isdiscrepance in surface sculpture between
the right and left valves. REEVE on theother hand said this species is equivalve
and he did not mention discrepancy between the valves. Concerning the .formof the muscle scars, this species as wellas Anadara (Scapharca) takaoensis (No-4.91.

A nada1·a j1·ont Southwest .Japan

MURA) and A nadara (Scapharca) suzukii
have L-formed posterior muscle scarthough the anterior one is rounded (Fig.
1, Pl. 10, fig. 2). The ligamenta! area isdepressed trigonal in form. turned anteriorly, being shorter in the anterior
half and, longer and narrower in theposterior half, with the irregular chevrons
rather few in number. Although No~IURA (1933), NmtuRA and ZINBO (1936)
and iviAKIY A:\IA (1958) considered Ana·dara (Scapharca) suzukii (YOKOYAMA) to
be a synonym of Anadara (Scapharca)
tricenicosta (NYST). this species differsfrom Anadara (Scap/wrca) suzukii (YOKO·
YAMA) statistically, but coincides with
.Scapharca phi/ippiana DUNKER.
Geologic Ocwrrence: Tokazan Formation in Formosa, Pliocene; Naganuma
Formation, Kanagawa Prefecture, Pleistocene (in part) and Recent.

Anadara (Scapharca ?) shizuokaensis
NonA, n. sp.
Pl. 11, Figs 7-8

Shell large, much swollen. thick. stout,
rounded ovate except for beak, longer
than high. inequilateral. anterior side
short and posterior produced, ventral
margin bro:tdly convex. Dorsal margin
straight, anterior dorsal margin shorter
than posterior one. Shell surface sculptured with strong rather narrow, flattopped radial ribs which are strong,
sharply squarish in cross section andnarrower than their interspaces. Interspaces sculptured with concentric linesof growth, some lamellae cross backs ofradial ribs. Umbo swollen, beak small.
incurved strongly directed and situatedanteriorly. Ligamenta! area trigonal inprofile, flat, rather wide, with low angled.
chevron grooved. Ligamenta! are a bound·-ed by narrow and deep furrows along103

dorsal margins.
Hinge line straight.
Teeth rather large and decrease in sizenear boundary of anterior and posteriorsides, and ventrally convergent at both
extremities. Anterior muscle scar ovate·
ly rounded under the dorsal end, pos·terior one larger and roundly quadrate.
Pallial line smooth hardly incurved at
posterior muscle scar. rather deep vent·ral margin of inner shell strongly cren·ulated. Dimension (in mm.) of holotype;
Length 80.2, height 62.1, width 31.2.
height of ligament 8.6. length of ligament
55.8, length of teeth 53.1. radial ribs 37
in number.
Holotype: IGPS coli. cat. no. 78919.
Collector T. SATO .
Type Locality : Hosoya, 1\itaogasamura, Ogasa-gun. Shizuoka Prefecture.
.Nango Sandstone and Mudstone Alternation, Pliocene.
Remarks: The Pliocene form of Ana·dara from the Kakegawa district, Shizuoka Prefecture had been known under
the name of Anadara castella/a (YoKO·
YA:\IA) and Anadara suzukii (YoKOYA~IA).
The former one was described by YoKO·
YA:\fA as a subspecies of sa/owi. YoKO·y A:\! A stated that this species is characterized by the shell being very inequilateral, the anterior side rounded, theposterior more or less truncated, thesurface with a blunt edge running fromthe beak to the posterior ventral corner.
There are 36 radial ribs or there-about
and they are broad, usually flattened,
separated by narrower interspaces andthe area is yery narrow.
Accordingly the present new species
differs from .rlnadara caste/lata (YOKO·YA~IA) in having no edge along the pos·terior border and by the narrow, sharply squarish radial ribs and by the ligamenta! area being rather broad. ilnadara(Scapharca) taiwanica NonA (!'viS) from
Formosa is another allied species but itHiroshi NODA

101

differs from the present new species in
its more swollen shell and rather wide.
low, flatly topped radial ribs. A.nadara
nmmaensis OTUKA is characterized by
its narrower umbonal area and fiat shellcompared with the present new species.

having a depre.ssed area along the pos-terior margin differs from the present
new species though number of radialribs is similar.

Subgenus Tosarca NonA, n. subgen.
Anadara (Scapharca ?) iwaslzibaraensis
NouA, n. sp.
Pl. 10. Fig. 15

Shell medium in size. rather thick,swollen, inequilateral in form. very pro·soclinal, anterior side narrowly rounded
and posterior side broad, somewhat truncated, although somewhat poorly preserved. Dorsal margin slightly arcutated,ventral margin runs obliquely from narrower anterior to broader posterior end.
Surface sculptured with strong radialribs which arc rather wide, low, smooth,fiat-topped with their interspaces rathersmooth but having concentric growthlines transversing the radial ribs. Radialribs 31 in number, and with no depressedarea along posterior margin. Umbo swol·len, flat, lower. Beak small, pointed.
situated at one third shell length fromanterior side. Ligamenta! area narrow.
bounded with rather strong furrows ofsmall teeth perpendicular to hinge line.
Pallial line rather deep and smooth. An·
terior muscle. scar smaller than posterior
one. subrounded. Inner Yentral margin
crenulated shallowly.
Holotype: IGPS coli. cat. no. 29050,
Collector S. NoMURA.
Type Locality:
Iwashibara, Kami·
tareki-mura, Ogasa-gun, Shizuoka Pre·
fecture, Dainichi Formation, Pliocene.
Remar!?s: The present new species
resembles the Recent Anadara (Scaph·area) broughtnii (SCHRENCK) but theformer has fewer radial ribs. il.nadara(Scajllwrca) subcrenata (LJSCHKE) in

Type species: Anadara (Tosarca) tosaensis NODA, n. sp., Ananai Formation,
Kochi Prefecture. Pliocene.
Diagnosis :-Shell very incquilateral,
trapezoidal in form. anterior very narrow, posterior produced and obliquely
truncated behind. Surface sculptured
with strong, numerous. dichotomous orpartly dichotomous radial ribs, sometwice dichotomous at both extremities
with wide depressed area extending frombeak to posterior margin. Umbo swollen.
Ligamenta! area rather narrow, more orless depressed from beak to hinge line.
Inner margin crenulated at ventral mar·gin. Teeth a continuous series.
Remarks: This new subgenus is pro·
posed for the species of :lnadara commonly known as /lnadara sedanensis(tvlARTI:'\), Area llellica/a REEVE andAnadara tosaensis Nou,\, n. sp., thelatter of which is selected as the typespecies of the new subgenus. Anadaras. s. and Scaplzarca are distinguishable
from the present new subgenus by theirunique inequilateral shell with trapezoidal
form, more S\vollen, slightly medially
impressed umbonal area. and narrow
ligamenta! area which is depressed in
profile. Although these features arefound in Anadara or Scapharca, Tosarca
is characterized in having the above
mentioned shell form and shape of
dichotomous radial ribs. These charac·ten; are easily grouped up from other
Anadara species.
l'vloreover this newsubgenus is characteristic of the IndoPacific Province.

491.

A.nada1·a from Soutlm•est Japan

A.nadara (To.~arca) tosaen5is
NODA, n. sp.
Pl. 11, Figs. 11-13

Shell medium in size, test very thick,stout, subtrapezoidal. inequilateral, longer
than high, slightly concave with wide
posterior depressed area. Dorsal margin
slightly arcuated, passing into angulated
posterior and anterior sides. Anterior
ventral margin smoothly rounded, pos·terior ventral margin nearly straight.
Posterior side truncated. Beak small,lo\v, situated anteriorly, umbonal area
flat, slightly depressed medially. Ligamental area very narrow, depressedfrom beak to hinge line and with two
chevron grooves, covered with longitudinal striations. Hinge line straight withperpendicular small teeth, ventrally convergent at both extremities. Surface
sculptured with rather strong wide, low.
flat-topped radial ribs, 43 in number.
lnterspaces of radial ribs very narrow.
Anterior 10-11 ribs dichotomous, backsof radial ribs and posterior 14-15 radialribs sculptured \Vith two or three veryfine longitudinal furrows on their backs,
middle part of shell without furrows on
their backs of radial ribs. Dimension (inmm.) of holotype; Length 52.'1. height52.0. length of ligament 37.8. angle of umbo106", angle of hinge line and posteriorend 103'. and radial ribs 43 in number.
Holotype: IGPS coil. cat. no. 51609,
Collector S. NOMURA.
Type Locality : Oono. Yasuda-mura.
Aki -gun, Kochi Prefecture. Ananai For·mation, Pliocene.
Remarks: The present new species
resembles ilnadara iu.wtonoensis NooA(~IS) from Yamanashi Prefecture in typeof furrows on backs of the radial ribs
but differs in their form. Anadara (Tos·area) sedanensis (lVIARTIN) is allied to105

this new species in form but the former
is sculptured with only dichotomousradial ribs while the latter does not carrythem in the middle part of the shellsurface though their shell form and shapeof the radial ribs are similar with one
another.
Reference cited
CHA:>~G. L. S. (1958):

Stratigraphy of Taiwan
and its correlation with adjacent Areas.
Formosau Scieuce, Vol. 12. No.1. p. 1328. I table, 1 geol. map.
DUNKER. vV. (1882): Index l\'iolluscorum
Maris Japonice. p. J-301. pl. 1-16.
HATAI. K. (19.U) : Sundry Notes on theJapanese Pliocene (1). japan. jour. Ceo/.
Geogr .. Vol. 18. Nos. 1-2. p. 69-86.
- - (1960) : Japanese Miocene Reconsidered.
Sci. Rep., Tohoku Unil' .. 2nd Ser .. Spec.
Vol., !•io. 4. p. 127-153.
(1962) : Mizuho To. ibid.. 2ud Ser ..
Spec. Vol .. No . .5. p. 329-348.
lLo\NZAWA. S. (1935): Topography and Geo·logy of the Riukiu Islands. Sci. Rep ..
Tohoku Imp. Univ .. 2nd Ser., Vol 17. p.
1-59. pis. 1-15, 5 maps.
hoiGAWA, J, (1953) : A new species of fossil Siphonalia from the Miyazaki Group.
Venus. Vol. 17, No. 4. p. 213-218, textfigs. 1-4.
IwASAKI, Y. (196<1) : Notes on the Historical
Changes of the japanese Tertiary Anadara (in Japanese with English abstract).
l'enus. Vol. 22. No. 4. p. 379 .. 389, textfigs. 1-2.
KATTO, J., NAKAMURA, J. and TAKAYA:>IAGI,
Y. (1953) : Stratigraphical and Paleontological Studies of the Tonohama Group,
Kochi Prefecture. Japan. (in Japanesewith English abstract). Res. Rep., Kochi
Unit~., Vol. 2, No. 32. p. 1-15, pis. 1-2,
tables 1-3. text-figs. 1-2.
and OzAKI, II. (1955) : Miocene Nobori
Formation of Kochi Prefecture, Japan. (inJapanese with English abstract). ibid ..
Vol. 4, No. 1, p. 1-7, tables 1-3. textfigs. 1-4.

10()

Hiroshi NOJJAKIRA, T. (1954) : Coloured Illustrations of
the Shells of Japan. l/oikusha, p. 1-204,
pis. 1-67.
KoBELT, ',V. (1891) : Conchylien-Cabinet in
MARTIN und CHEJ>I:XITZ. Gattung Area
L., p. 1-238, pis. 1-49.
-KOTAKA, T. (1959) : The Cenozoic Turritellidae of japan. Sci. Rep., Tohoku Univ.,
2nd Ser, Vol. 31, No. 2. p. 1-135, pls. 115, text-figs. 1-10, text-fig. A. charts 1-8.
MACNEIL, F. S. (1960) : Tertiary and Quaternary Gastropoda of Okinawa. U.S.
Geol. Surv. Prof. Pap., JVo. 339. p. 1-I.JS,
pls. 1-19.
MAKJYAl\IA, ]. (1924): The Evolution of
Umbonium. japan. jour. Geol. Geogr.,Vol. 3. i\ios. 3-4, p. 119-130, pl. 20.
- - - (1927) .: :\lolluscan Fauna of the Lower

Part of the Kakegawa Series in the Province of Totomi, Japan. Mem. Col/. Sci.,
Kyoto Imp. Univ., Ser. B. Vol. 3, p. 1147, pls. 1-6.
- - (1931): Stratigraphy of the Kakegawa
Pliocene in Totomi. Ibid., Ser. B. Vol.
7, p. 1-53, pis. 1-2, 1 geol. map.
- - (1941) : Evolution of the Gastropod
Genus Siphonalia with accounts on the
Pliocene Species of Totomi and other
Examples. Ibid., Ser. B, Vol. 16, No. 2,
p. 75-93. pis. 3-6, text-figs. 1-4.
- - (1958) : Tertiary Fossils from the various localities in japan. Palaeont. Soc.
japan, Spec. Papers, No. 4, Part 2, pls.
25-57.
- - and SAKA~IOTO, T. (1955) : Explanatory
Text of the Geological Map of Japan,

Explanation of Plate 10(All figures in natural size)
Figs. 1-2. Anadara (Scapharca) tricenicosta (Nvs-r), p. 102-103
1. Left valve. 2. Inner surface of right valve. IGPS coli. cat. no. 37591. Locality; 300m.
East of Hakushaton, Chikunan-gun. Shinchiku-shu. Formosa, Tokazan Formation, Pliocene.
Figs. 3-7. Anadara (Scapharca) suzukii (YoKOYA:-IA), p. 100-101
3. Right valve. 4. Inner surface of right valve, 5. Showing the ligamenta! area, 6. Innersurface of fig. 7, 7. Left valve. IGPS coil. cat. no. 54606, Locality: Tonohama, Yasu(lamura, Aki-gun, Kochi Prefecture. Ananai Formation. Pliocene.
Figs. 8-9. Anadara (Scapharca ?) sp., p. 101-102
IGPS coli. cat. no. 90033, Locality; Tonohama, Yasuda-mura. Aki-gun, Kochi Prefecture,
Ananai Formation, Pliocene.
Figs. 10-13. AllC!dara (Scapharca) suzukii (YoKOYAMA), p. 100-101
10. Right valve. 11. Inner surface of fig. 10, 12. Right valve, 13. Inner surface of fig. 12.
IGPS coil. cat. no. 29244. Locality: Tombe, Kamitareki-mura, Ogasa-gun, Shizuoka Prefecture, Dainichi Formation, Pliocene.
Fig. 14. .ilnadara (Scapharca) takaoensis (NoMURA), p. 101
Left valve, IGPS coil. cat. no. 51306, Locality; Gabesoga, Kunigami-gun, Okinawa Island,
Nakoshi Sandstone, Pliocene.
Fig. 15. Anadara (Scapharca ?) iwashibaraensis NooA, n. sp., p. lO<lHolotype, IGPS coli. cat. no. 29050. Locality: lwashibara, Kamiogasa-mura, Ogasa-gun,Shizuoka Prefecture, Dainichi Formation. Pliocene.
Figs. 16-17. Anadara (Scapharca) tricenicosta (NvsT), p. 102-103
16. Umbonal view showing the ligamenta! area, 17. Left valve. IGPS coli. cat. no. 1172<1,
Kii Peninsula, \Vakayama Prefecture, Recent.
Abbreviation:

IGPS=lnstitute of Geology and Paleontology, Tohoku University. Sendai. Japan.

NODA:

Anadara from South'West JapanKu~ l i\Gi\ 1

Photo.

Plate 10

491.

Anadara. fton~ Southwest Japan

Scale I : 50.000. Mitsuke and Kakezuka.
(in Japanese with English abstract).
Geol. Surv. ]a/Jail, p. 1--n.
MARTI:-1, K. (1909-1922): Die Fossilien vonjava. Samml. Ceo/. R-,\lus., Leiden N.F.
Bd. 1. p. 333-538, pis. •10-63.
MASUDA. K. (1962): Tertiary Pectinidae ofjapan. Sci. Rep .. Tohoku Univ., 2nd Ser.,
Vol. 33, No.2. p. 117-238. pis. 1-10. textfigs. 1-7.
XoML'RA, S. (1933) : Catalogue of the Tertiary and Quaternary Mollusca from theIsland of Taiwan (Formosa) in toe Institute of Geology and Paleontology.
Tohoku Imperial University, Japan. Sci.
Rep .. Tohoku Imp. Univ., 2nd Ser .. Vol.
16. No. 1. p. 1-106. pis. 1-4.
- - (1937) : The Molluscan Fauna from the
Pliocene of Tosa.
japan. jour. Ceol.
Geogr .. Vol. 14. Nos. 1-2. p. 66-90. pl. 6.
--and IIAT,\1, K. (H)36): On some speciesof the Genus Area from the Neogene of:'lfortheast llonshu. Japan. Ibid., Vol. 13,
Nos. 1-2. p. 6:~-70. pis. 12-13.
- - and ZINBo. N. (1934) : Marine Mollusca
from the Hyukyu Limestone of 1-i.ikai
Zima, Ryukyu Group. Sci. Rep .. Tohoku
Imp. Univ., 2nd Ser .. Vol. 16. No. 2. p.
109-164. pl. 5.
- - and - - (1936) : Molluscan Fossil fromthe Shimaziri Beds of Okinawa-zima.
Ryukyu Islands. Ibid., 2nd Ser .. Vol. 18.
/llo. 2. p. 229-266. pl. 9.
NYST. P. H. (18-18) : Tableau Synoptique etSynonymique des Especes Vivantes etFossiles de Ia Famille des Arcacees.
Part 1. Genera Area. .-lead. Roy. Sci ..
Letters Beaux .-Iris Be/g., Mem., Vol. 22 .
p. 79.
0TUKA, Y. (1930) : Some Geological Problem
at the Takanabe District, Miyazaki Prefecture. (in japanese). Geogr. Rev. japan,
Vol. 6. No. 7, p. 496-522. text-tigs. l-8.
- - (1931) : Early Pliocene Crustal C\Iovement in the Outer Zone of Southwest
Japan and in the ·• Fossa Magna". Bull.
Earlhq. Nes. Ins/., Imp. Univ. Tokyo. No.
9. p. 340-352.
- - (1932) : The PI iocene Crustal ;\lovements and Inclination of Coastal Ter-

107

races in Southeastern Kyushu. (in Japanese with English abstract). Geol. Re11.
japan. Vol. 8. p. 81-95. text-figs. 1-5. I
table.
- - (1932a) : Post Pliocene Crustal Movement in the Outer Zone of Southwest
Japan and in .. Fossa Magna". Bull.
Earthq. Res. Ins/., Imp. Univ. Tokyo. No.
10, p. 701-722.
- - (1935) : The Earthquake of Central
Taiwan (Formosa). April 21. 1935. andEarthquake Faults. (in japanese withEnglish abstract). 1bid .. No. 3. p. 22-27,
pis. 35. 36. 46. 56-63. 65-66, 90. 101. 10-L
122. 123. 126. 128. 130-132. text-figs. 1-26.
- - (1936) : Pliocene :\·Iollusca from Manganzi in Kotomo-mura. Akita Prefecture.
Japan. jour. Ceo/. Soc. Japan. Vol. -13.
No. 516. p. 726-736. pis. 41--12.
PRASHAD. B. (1932) : The Lamellibranchiaof the Siboga Expedition. Part 2. Pelecypoda. Result. Exp/or. Siboga. Monogr.
53. p. 1-353. pls. I -9.
REEVE. L.A. (184-1) : Monograph of theGenus Area. Conch. Jconica. Vol. 2.
Area. pis. 1-17.
REJ:-11.\RT. P. W. (1935) : Classification of
the Pelecypod Family Arcidae. Bull.
.\Ius. Roy. His/. Nat. /Jelg .. Vol. 11. p.
1-68. pi 1.
H1:-<. T. (1935) : Stratigraphical Studies on
the Younger Tertiary and Pleistocene
Formations of the Toyohara District.
Taityu Prefecture. Taiwan (Formosa).
.\lem. Fac. Sci . .-lgricull .. Taihoku Imp.
Univ .. Vol. 13. p. 13-30, pis. 1-7. 1 geol.
map.
ScnE><CK. H. G. and REI:"' HART. P. W. (1938) :Oligocene Arcid Pelecypods of the Genus
Anadara. .\!em. Mus. Roy. /list. Nat ..
Belg .. Fasc. 14, p. 1-73. pis. 1-6. tables
1-13, text-figs. 1-12.
SHUTo. T. (1952): Stratigraphical Study of
the Miyazaki Group. (in Japanese). Sci.
Rep., Fa c. Sci .. Kyushu Univ .. Geol. l' ol.
4. No. 1, p. 1-40. pls. l-8. text-figs. 1--4.
tables 1--L
- - (1955) : Amussiopec/etl from the Miyazaki Group, !vliyazaki Prefecture. 1'ra11s.
Proc. Palaeont. Soc. japan. N. S .. No. 20.

108

Hiroshi Nm>A

p. 101-110, pis. 16-17. text-figs. l-4.
- - (1956) : Urnboniinae from the MiyazakiGroup. japan. jour. Geol. Geogr.. Vol.
27. No. J, p. 47-6G. pl. 4. text-figs. 1-7.
tables 1-4.
- - (1957) : Crassatellites and lfenericardia
from the Miyazaki Group. A/em. Fac.
Sci., ](yushu Univ .. Ser. D. Vol. 6, No. 2.
p. 69-8!l, pl. 22. text-figs. 1-7, tables 1-3.
- - (l957a): Fossil Paphia from the l'vliyazaki Group. japan. jou1·. Geol. Geogr ..
Vol. 28. Nos. 1-3, p. 139-160, pl. 12. textfigs. 1-9. tables 1-6.
- - (1958): A Preliminary Note on theMedial and Late Cenozoic History in
Kyushu. (in japanese). Shinseidai no](enkyu. No. 28, p. 634-653, text-figs. 1-4- - (1958a) : Cranulifusus from the Miyazaki Group. Trans. Proc. Pa/aeonl. Soc.
Japan, N. S .. No. J /, p. 253-204, pl. 38.
text-figs. 1-3. tables l-3.
- - (l!l59): Olivid Gastropods from theMiyazaki Group.
japan. jour. Ceo/.
Ceogr., Vol. 30, p. 169-182. pl. II. textfigs. J ...l,- - (1960): On some Pectinids and Veneri ds
from the Miyazaki Group. Mem. Fac.
Sci .. ](yushu Univ .. Ser. D. Vol. 9. No. 3.
p. 119-14!), pis. 12-U. text-figs. 1-14.
tables 1-2.
- - (1960a) : Carditids from the MiyazakiGroup. Trans. Proc. Palaeont. Soc. japan.
N. S.. No. 37, p. 209-222, pl. 25, text-figs.
1-2.
- - (1961) : Palaeontological Study of thel'vliyazaki Group. Mem. Fac. Sci .. J(yusllll
Univ .. Ser. D. l'ol. 10. No. 2, p. 73-206,
pls. 11-13. text-figs. 1-23. tables 1-15.
- - (1964) : Naticid Gastropods from theMiyazaki Group. Trans. Proc. Palaeont.
Soc. japan. N. S .. No. 55. p. 281-293, pls.
42-43, text-figs. 1-3.
SuGIYAMA, T. (1935): On the Variation of
the shell of Li,·ing and Fossil Umbonium
from japan and its Evolution. (in Japanese). jour. Ceo/. Soc. japan. Vol. "12.
No. 502, p. 40cl-430. pl. 11. figs. 1-6.
- - (1935a) : On the Variation of the shellof Living and Fossil Umbonium fromJapan and its Evolution. (in Japanese).

Explanation of Plate 11(All ligures in natural size)
Figs. 1-2. Anadara (Tosarca) sedanensis (1·1ARTI:o\).
1. Showing the teeth and the narrow ligamenta[ area, 2. Left valve. !GPS coli. cat. no.
61388. Locality: Yard of Nakoshi Primary School. Nakoshi, Haneji-rnura. Kunigami-gun.
Okinawa Island, Nnkoshi Sandstone, Pliocene.
Figs. 3-6. Anada1·a (Scap/za1·ca) takaoensis (NOl\IURA), p. 101
3-4. Umbonal view. 5. Right valve, 6. Left valve. IGPS coiL cat. no. 51306. Locality:
Gabesoga. Kunigarni-gun, Okinawa Island. Nakoshi Sandstone. Pliocene.
Figs. 7-8. Anadara (Scafl/rarca ?) shizuo/wensis NniJA, n. sp .. p. 10:~-104
7. Right valve. 8. Inner surface of fig. 7. Holntype, IGPS coiL cat. no. 29180. Locality;
Hosoya, Kitaogasa-mura. Ogasa-gun, Shizuoka Prefecture. Nango Formation. Pliocene.
Figs. 9-10. Anadara (Scapharca) suzukii (YoKOL-\~IA). p. 100-101
9. Right valve. 10. Urnbonal view. IGPS coli. cat. no. 61387. Locality: Yard of Nakoshi
Primary School. Nakoshi. Ilaneji-mura, Okinawa Island. Nakoshi Sandstone. Pliocene.
Figs. 11-13. Anadara (Tosarca) tosaensis NooA, n. sp .. p. 105
11. Showing the depressed area along the posterior side with fine furrows on radial ribs,
12. Umbonal view and showing the depressed narrow ligamenta! area. 13. Left valve.
Holotype. IGPS coli. cat. no. 54609. Locality: Oono. Yasuda-mura. Aki-gun. Kochi Prefecture. Ananai Formation. Pliocene.

NODA:

Anadara from Southwest JapanK uMAGA I Photo.

Plate 11

491.

Ibid., Vol. 42. No. 503. p. 4~9-482, textfigs. 1-30.
SUZl'l<l, K. (Hl3,1) : On the Evolution of
Umbo11ium. (in japanese). Ibid., Vol. 41.
No. 485. p. 67-81. text-tigs. 1-4.
TAKAI. F. (1963): On the Boundary between
the Tertiary and Quaternary of Japan
from the viewpoint of Mammal. (inJapanese). Fossil No. 5. p. 162-165. 1
table.
Tst:cHr, R. (1961) : On the Late Xeogene
Sediments and l\lolluscs in the TokaiRegion, with notes on the Geologic History of the Pacific Coast of Southwest
japan. japan. jour. Geol. Geogr., Vol.
32. Nos. 3-4. p. 437-456. text-figs. 1-4,
tables 1-5.
UJIIE, H. (1962): Geology of the SagaraKakegawa Sedimentary Basin in Central
Japan. Sci. Rep., Tollyo Kyoiku Daigaku.
Sec. C. Vol. H. No. 75, p. 123-188. textfigs. 1-19, Append. Figs. 1-6, tables 1-3.
YAnE. H. and llATAI. K. (1942): Aclclitional

EnshushoHaneji-mura
HosoyaI washibara
Kaenzan
Kozan
Kunigami-gun
lVIiaoli

!?.~

.u~

.1±

;JjJ .11!! t!
~II
.ft
!!1l
!Iii
!k ~ ill
iff
LlJ
~

fti

10~}

Anada.ra. from Southwest Japan

!fi'i

lif>

~

Fossil from the Shimajiri Beds of Okinawa-zima. Ryukyu Islands. japan. japan.
jour. Geol. Geogr., Vol. 18, p. 71-78. pl. 7.
YOKOYA:O.IA, l\-1. (1923) : Terliary Mollusca
from Dainichi in Totomi. jour. Coli.
Sci .. Imp. Univ. Tokyo. Sec. 2. Vol. 45,
p. 1-18, pis. 1-2.
- - (1926) : Tertiary 1\lollusca from Southern Totomi. jour. Fac. Sci., Imp. Univ.
Tokyo, Sec. 2. Vol. 1. p. 313-364. pis. 3841.

- - (1926a) : Tertiary Shells from Tosa.
Ibid., Sec. 2. l'ol. 1. p. 365-368. pl. 42.
- - (1928) : Mollusca from the Oil Fieldof the Island of Taiwan.
Rep. Imp.
Geol. Surv. ]apa11. No. 101. p. 1-112. pis.
1-8.
- - (1928a) : Pliocene Shells from Ilyuga.
Jour. Fac. Sci .. Imp. U11il'. Tokyo. Sec. 2,
Vol. 2. p. 331-350, pis. 66-67.
- - (1929) : Pliocene Shells from Tonohama.
Tosa. Rep. Geol. Surv. japan, No. /04,
p. 9-17. pis. 7-8 .

NakoshiOono
Shinsui
Takao-shu
Tokazan
Tom beTonohama

frl• I'd

~

};,

~tf

i;fi

*

t:j !11l HI!!ft. ¥,~ ill

t'l!S
'Iii
f.'.t IJf 1ft

Trans. Proc. Palaeont. Soc. Japan, :>1. S., No. 59, pp. 110-113, pl. 12. Sept. 20, 1965

492.

A GIGANTIC SCALLOP FRO~l THE SEA BOTTO)! OFF THE
DANJO ISLANDS, NAGASAKI PREFECTURE, JAPAN*
JO]l NAGASAWA
Institute of Earth Science, Tokyo Gakugei University

N:~~ljl. Yl:tctf~i<P ~JittJ,I?!*!.IH.- t-=E!~"t.r: :t- J :r ¥t : !~lKJ~IJI;.1LJm71J~;:::.i!I~ ·YJ:tct'F~i'P(1)ifjj~;IJ. ~ CL$lltilllUfii!J>lH~(1)~i:::.n ·n··:r-c ~l...tJf ~~'l.t.:;k1~(1) Mizultopecten W1&) ft;fil:::.

.c..:: l::.tlH~--t ~o .c..;/1.!1J'~i~l:::.;k~(1) Q -ck~ ~ ·c:t * J 7 ~(1)(tfl!IH"C:I:t~l? <ii:J:W<t.~:H¥~1ttJJ:0)/1al. ·~li\Yf(1)J}df;!{(1):jR!t.~tJ· ~. ~(1);k h ·li.LI:.'I4.1jlj~Pf(1)~ff!:-Ci:tfJ: <-c.~f(Et:J~?"'!U: !j!/]lijfL t.:o - Jt ~~titl!:IJICf~.~.-t ~ :t- J :7' 7i .-f t::.f!;J.
t.:J:.;:, .?n:;t, 7.JtJ'. ~'F~t::.'i:-(1) ~l'lc~ .Th\1-"'o J:. }J~lll! -c:;t, ~0 ~Jm...t(1) *~ n' ?.;.7.J c.. M.

-?I. ·'"C,(f.ji:::. :b I~ I? Lv' ~ (1) l: \.\!.5o i~tJ:JiY:

tryblium group ~. M. kimurai-Al. tokyoe11sis l:::.rjij~(l);t, o.f!l!i:. ~ ;{. l?.tl.otJ:, let1;1J(1)Mizuhopectell (1)lJ!(1)tp"t;·.C..tL::::.-i&-t ~ ~ 1:>:tfJ:I.'(1)~, Jill!:. L -cm15--t Oo ll.]ftl!ifii
tl.t .1:. ffi[Ji:: L:'::iR ~j{ 11:*0Introduction and Acknowledgements
The specimen described in this article
was dredged by a coral net from the sea
bottom off the Danjo Islands near theGoto Islands, Nagasaki Prefecture. few
years ago.
In the spring of 1964, the writer at
the suggestion of Professor N. SAKAZD:\IE
of the Doshisha University in Kyoto,
visited Fukue Islet, one of the Goto
Islands, and was fortunate in being able
to study a fossil specimen which is now
preserved in the collections of l'vlr. I.
KAMAGA, a resident of Fukue Islet. Thisfossil A1izuhopecten is interesting because
it is the largest one hitherto known fromjapan. The comparatively thin test andthe morphological characters of this specimen indicate that its unusually large size
is a specific character, rather than the* Received Jan. 29. 1965; read jan. 2-1, 1965
atTokyo.

result of abnormal growth of the shell.
The external surface of this shell isbluish gray and partly covered with calcareous organic remains. The shell ismore or less water worn and damaged
slightly, but the specific characteristicsof the specimen are clear and show it tobe an undescribed form.
The writer is greatly indebted to Professor Nakao SAKAZUME for his kind
help and encouragement during the courseof this study.
The writer wishes to express his deep
gratitude to 1vlr. !taro KAMAGA of Fukue
Islet, for kind permission to study the
specimen, to Professor Kotara HATAI of
the Tohoku University for his kindness
in reading this manuscript and for his
advice, to Dr. Koichiro MASUDA of thesame university for the permission to
study his collection, and to Dr. Shozo
I-lA y AS AKA of the same university for
his kind help.
110

G1'ga.nhc Species of lllizuhopecten
Description
Family Pectinidae
Subfamily Pectininae
Genus Alizuhopecten l\IASUDA. 1963

Mizuhopecten kamagai
NAGASAWA, n. sp.
Pl. 12, figs. 1-7

Hololype :-A right valve in the pos·session of ~vir. Itaro KAMAGA. a residentof Tomie·machi, Fukue Islet in the Goto
Islands. Nagasaki Prefecture. japan.
Description :-Shell very large measuring 28 em in length, 27 em in height,
being slightly broader than high, suborbicular. equilateral, rather thin andmoderately inflated. about 4.5 em in
depth of right valve, apical angle about
110 degrees.
Right valve with 35 distinct. but comparatively low. round topped radial ribs,
which are considerably broader thantheir interspaces and in the upper partsof disc often diYided into two partsby fine. shallow and narrow longitudinal
striae or furrows, but on the central or
low·er parts of the shell by two rather
distinct · shallow longitudinal furrows
dividing ribs into three parts in general
as seen in Mizulwpecten yamasakii (YoKOY A:\!A): base of furrows and interspaces and sides of radial ribs concave.
Among the 35 radial ribs on the surface, no furrows were recognized on nineof the radial ribs because of being covered with foreign matter and to thewear. but one furrow was observed oneach of 13 radial ribs and two on another 13 radial ribs.
At about the upper half of the discor at the younger part a series of alternating elevated radial ribs and a few low

111ones were observed, that is, 4""'6 radialribs which form a group are more elevated than the rather low I ""'2 radialribs which are situated between thegroups of elevated radial ribs. Altogether
five such groups, counted from the rightmargin of shell could be recognized. but
this feature is obscure at the left submargin of the shell as seen often near
the beak of Alizuhopecten tolzyoensis (ToKU:-<AGA} and also tend to become obscure
towards the lower part of the disc.
Auricle large: hinge-length/height=
0.55, height of auricle/height=0.18, lengthof anterior auricle much larger than thatof the posterior. anterior auricle ornamented with concentric striations andprovided with shallow byssal notch. radial
threads obscure ; posterior one sculptured
with seven radial riblets and concentricstriations; hinge with rather faint cardinal crura and a large triangular shaped
resilial pit provided with lateral ridges.
Comparison and affinity :-Mizuhopecten yessoensis yokoyamae (MASUDA) (M.
poculum subsp. a, (AKIY A:V!A)) from Chikagawa and M. kurosawensis (YOKOYAMA) from Onma, which are included
into the M. poculum group can be distinguished from the present one by theirelevated, more or less squarish. roundtopped radial ribs which are nearly equal
to or narrower than their interspaces inbreadth and the M. yessuensis (JAY)group. by generally undivided fiattish
radial ribs, left auricle truncated behindin general. and the resilial pit being
rather small in height compared withthe present one.
Among the numerous species of scallops having the interspaces narrower
than the radial ribs on the right valve
in Mizuhopeclen, there are two distinctgroups as follows: The one group possesses broader and less numerous radialribs which are furnished with radial112.Joji NAGi1S.:1 WA

threads, or divided into riblets, andthe other group has more numerous
radial ribs which are not so broad, butequal or sometimes subequal in theirbreadth and often furnished with one or
two radial furrows. or in parts of thedisc, divided into two parts.
MizulwjJeclen kimurai (YoKOY Al\IA) and1U. tokyoensis and their allies belong to
the former group, and the latter group
includes M. nakatombetuensis (AKIY A:'.! A),
M. yamasallii (YoKOYAMA). M. tryblium(YOKOY A~! A) and their allies.
The characteristics mentioned above-of the radial ribs of the two groups arerecognized in the present single speci·men, namely. the characteristics of theformer group, especially near the beak,and that of the latter group on thelower half of the shell, as already de·scribed.
Therefore, the arrangement of theradial ribs on the upper half of the discin this specimen is similar to the radialribs of i\1. kimurai whereas the features<>f M. lokyoensis may be seen on thedisc as a whole.
This characteristic seems to be im·portant from the phylogenetic point ofview.

But. as the extraordinary arrangementof the radial ribs on the upper half of
this specimen is considered to be only
an indication or the remnant of thecharacter which the AI. kimurai groupand its ancestor possessed, the present
one may be incorporated into the lattergroup mentioned above or treated as a
new form.
Though the mode of biufrcations of
the radial ribs of the present new species
is the same in M. yamasakii and its
allies, this one is distinguishable fromthem by its larger auricles and by theleft auricle being not truncated behind
and in the shell shape having the length
exceeding the height.
Especially, M. yamasakii is distinguish·
ed from this species by its conspicuous
stout lateral ridges on both margins of
the resilial pit.
The present species resembles those of
the l1·yblium group, but it can be distin·
guishcd from M. tryblittm lryblium (YO·
KOYAMA),

M. t. shinshuensis (AKIYA:\lA)

and AI. t. ibaragiensis (MASUDA) by having
larger number of trifurcate radial ribs
and its large right auricle, and also from
M. t. kintaichiensis (MASUDA) by thelarge number of radial ribs and by the

Explanation of Plate 12
Figs. 1-7. Mizuhopecten kamagai, n. sp.
1. Right valve, Holotype, x lf3.6, from the bottom off the Danjo Islands, Nagasaki Prefecture, now kept by Mr. I. KAMAGA.
2. Interior view of Fig. 1. ca. x 1/3.5.
3. Posterior profile of Fig. 1. ca. x 1/3.5.
4. Left auricle stripped of covering substances, and the ·1 groups of elevated radialribs showing the special arrangement; a part of the plaster model of Fig. 1.
5. Right auricle stripped, partially, of covering substances, its concentric striations andthe 6 groups of elevated radial ribs; a part of the plaster model of Fig. 1.
6. The half part of the hinge area of Fig. 2 showing a cardinal crura; a part of theplaster model of Fig. 2.
7. Surface sculptures of several radial ribs which are trifurcate or bifurcate at the
middle part of the left ventral margin: a part of the plaster model of Fig. l.

NACAS.4 WA:

Plate 12Gigantic species of Mizuhopecten

57Giynnhc Species of Miznhopecten
left auricle being not truncated.
It is noticed that in AI. tryblium tryblium, the outline of both lateral ridges
around its resilial pit is roundish in shape,whereas it is triangular in the present
one like M. yessoensis and AI. tokyoensis.
M. nakatombetuensis (AKIYA~!A) differsfrom this new species by the elevatedflat-topped. squarish radial ribs.
In short, this species can not be identified with any known species of ,\fizuhopecten (=Patinopecten of authors) inJapan. or with forms of Patinopecten of
Northwest America. therefore the writer
proposes the new species name ... kamagai" after the name of the collector.
Geological .-lge :-Probably Pliocene.
inferred from the reasons: Among thenumerous species of fossil Mizulwpecten(recorded as l'atinopecten), the species
having more than 20 radial ribs andmorphological characters related to thisnew species are known only from the
Pliocene of japan and, abundant Pliocene
fossils have been dredged from the sea
bottom of the japan Sea, as off lhe coastof Yamaguchi, Shimanc. Niigata, Yamagata, and Akita Prefectures. and fromthe Korea and Tsushima Straits.
Ht>ference Cited
M. (1962) : Studies on the Ph~·Io­geny of Patirwpecten in Japan. Tokyo
Kyoiku Daigaku, Sci. Rep., Sec. C (Geol..
.\lin .. Geogr.). mi. 8. no. 74. pp. 1-63. pis.

AKIYA:\IA.

Akita
t.k
E!:J
Danjo Islands 9.l:tc9!JW;
Fukue Islet:ffii ):[ li:;
Goto Islands
li,fi!;Jlj!If;
Niigata
'lfr
if.J
Onmma
A.
~

113

I-VIII.
K. (1963) : New species of Gadus
from Lhe Pliocene of Japan. l'a/aeonl.
Soc. japan, Trans. !'roc .. N. S .. 110. •19. pp.
25-28. pl. 5.
lToiGAWA, ]. (1958): 1\lolluscan Fossils fromthe Niitsu. Higashiyama and Takezawa
Oil-Field. Niigata Prefecture. Japan.
Univ. Kyoto. Colt. Sci., Mem .. Ser. B. vo/.
.\'XIV. no. 4. pp. 249-263. pl. 1. figs. 8-9.
l\IASCDA. K. (1960) : On the Miocene Pectinidae from the Environs of Sendai: Part
16, Pecten kimurai YoKoYA~IA and PalIiolum cf. Peckami (GADB).
l'a/aeont.
Soc. japan, Trans. Proc., N. S .. no. 38. pp.
2-19-262. pls. 29-30.
- - (1962): Tertiary Pectinidae of ,Japan.
Tohoku Unir .. Sci. Rep., 2nd Ser. (Geol.).
vol. 3 3. no. 2, pp. 1-238. pis. 18-27.
- - (1963): The So-called Palinopec/en of
Japan. Palaerm/. Soc. japan. Trans. Proc.,
N. S., no. 52. pp. U5-153. pis. 22-23.
To~IIZAWA. T. (1958):
Studies on Fossil
from the Kami-Minochi District. Nagano
Prefecture, in T. and K. YAel. Geology
oj Kami-Minochi-gzm (in Japanese). pp.
317-347. pl. IV. lig. 10.
YoKOYA~IA. lVl. (1925):
Tertiary Mollusca
from Shinano and Echigo. Imp. Univ.
Tokyo, Fac. Sci., four .. Sec. 2. 11ol. I, pt.
I, p. 17, pl. 5. tigs. 1-2. pl. 6, figs. 1-2.
- - (1926): Fossil i\'lollusca from the OilFields of Akita. Ibid .. vol. 1. pt. 9. p.
388. pl. ·15, fig. 3.
- - (1926) : Tertiary l\lollusca from the OilField of Embets and Etaibets. Ibid., vol.
1' pt. 7. p. 2-15. pl. 32. fig. 1.
- - (1927): Fossil Mollusca from Kaga .
Ibid .. mi. 11. pt . .J.p. 180. pl. 49, fig. 1.
HATAI.

Shimane!lh.!U
Tomie-machi'1& 1t IIIJ
Tushima Straits ;{:(',tlj~tild:
Yamagata
111
JrJ.
Yamaguchi
LlJIITrans. Proc. Palaeont. Soc. Japan, N. S .. No. 59, pp. 114-125, pis. 13. 14. Sept. 20, 1965

493.

ON A LOWER CRETACEOQS PELECYPOD ... CYRENA"
NAUJ.liANNI. FR0:\1 JAPAN*
ITARU HAY AMI and !SAO NAKAI
Department of Geology, Kyushu University~fm~j!ft*i:J'*Ji!~ "Cyrena" naumanni t::.\, ·--=>"'C:

1890 f1 t1"Cyrena" naumanni NEU~tAYR,<11, I? ;;f.:~~ s~* ~~fi\ICI)tJi:tl /fll~r:.~j.ii· Q::. C. tJ:~ !?it., tl1li'\f!1t:ti'I:..:~tt-t.. ·(i:ij

fii$f.qJr\Jf(f'f.!ll}J!Iml!¥0)t:p '"C'J:l: 13 ~;ft. "'C ~t-:N\-c·t, QIJ·..

-t:'CI)f.f~~ ..tCI){.ir.[i1tf1;;pB]Jff'ti-ct,--:>t-:,~lll•~~ft/.ji;f!i!CI)m:t~:;lll!-c·t, Q :ft(Ch~Jmi!iilll~l.1!!CI)W!Ji:ti:.:tu~r, -c~~CI)t'\'i*~f*~ ~..-. mt:t~.bn;;t.t..:~.*. i:.CI)N\fi VoKEs (1946) tJ~ Lebanon Cl) Aptian ~ii'G~~L-t-: Proto·

cyprina Cl).j~!;i'i;~I:.Jll{J'):t" Q::. C. iJ'biJ•--=>t..:o ::. .:.1:. Prolocyprina ~~ j!}}E~ L. -c, N\CI)~i:'.l\t\t~11--=>t-:o ;;f.:.ifl::t. Y, 7~t:.~*L- f,: Eomiodon Cox. 1935 ~:.rk'.lti' J.) C.~;;{_ I? ;ft., -'CCl)~~.m.i1!ft Corbiculidae CI)~M.fiq C. ft.1N*t'!'~jl:.~ IJ. CASEY (1955) Cl):;g~L. t..:: Neomiodon ti dae 1:. -35'£-t .Q o
J2f Jj( m- · ~' .15 r}]

Introduction

from the Ryoseki group and its comparable strata at various localities of theOuter Zone of Southwest Japan and alsoof Northeast Japan. Since index fossils
are scarce in the Ryoseki fauna, the occurrence of this species has been parti ·cularly noticed by a number of strati·
graphers. (Text-fig. 1)"Cyrena" naumanni NEU:>.IAYR is acelebrated pelecypod which occurs com·monly in the brackish-water deposits of
the Ryoseki group of Japan. It was
first described by NEUMAYI{ in NAU·
MANN and NEUMAYR (1890) from Yanagidani of the Katsuuragawa basin of east·
ern Shikoku. NAUJ\IANN and NEUMA YR
interpreted it to be a Jurassic species.
but the actual locality is situated in theoutcrop area of the Tatsukawa formation. which is a representative of the
Ryoseki group in this area and is pre·sumed to be Neocomian (probably lower
Neocomian) in age. At the same time
NEUMAYR described also Cyrena gravida
and Cyrena lithocardiurn from the same
locality. but, as interpreted by many
authors, the two must be synonyms ofC)rena naumanni.
Subsequently the present species wasreported to occur by many stratigrapherso-;....~~....;;.;300Km

Do
Text-fig. l.

* Received Feb. 29. 1965: read june 20. 1965.
aL Kanazawa.

114

Map indicating the localities ofProtocyprina naumamzi.

493.

On a Lowe1· C1·etaceous Pelec1J1Jod. "Cyrena." 1ta1wwnni

Y ABE, NAGAO and SHIMIZU (1926) re·
described many specimens from Yanagidani and referred several ones from the
Shiroi formation of the Sanchu area ofthe Kwanto mountains to Cyrena naumanni. Besides, this species has beenreported to occur from the Kawaguchi
formation of the Yatsushiro area (MA·TSUMOTO and KAN!I.IEI~A. 1952: MATSUMOTO, 1954), the Ryoseki formation of
the Monobegawa basin and in the vicinity of Kochi City, the Yuasa formationof the Yuasa-Aritagawa area (MATSUMOTO, 1947; MATSUMOTO, 1954). and
the Ayukawa formation of the Ojika area
(0:->uKI, 1955).
Little has been done, however, about
the palaeontological reexamination ofthis pelecypod. jurasso-Cretaceous nonmarine pelecypods were investigated by
KOBAYASHI and SUZUKI (1936, 1937, 1939).
They assigned some other Lower Cretaceous cyrenoids to Polymesoda RAFINESQUE, 1820. Since then, Cyrena naumanni
has been conventionally referred to Polymesoda and especially to its "section "Jsodome/la KOBAYASHI and SUZUKI, 1939,
without any solid foundation (SUZUKI.
1949, etc.). IIAYAMI in MATSUMOTO(1963. ed.), in which NAUMA!'<N and
NEUMA YR's original figures of Cyrena
naumanni, C. gravida and C. lithocardium were reproduced, pointed outthat the reference of "C." naumanni to
Polymesoda is not acceptable and that
it would belong to an unnamed genus.
Incidentally, Polymesoda is now livingin the brackish- and fresh-water environments of North and Middle Americas (PRIME, 1865; KEEN, 1958). and thegenus is quite unrelated to japaneseCretaceous cyrenoids which should be
mostly referred to other groups thanthe Corbuculidae.
In 1963, we collected a large number
of well-preserved specimens of "Cyrena"

115.

narmranni from the type locality, i.e.
the Tatsukawa formation of Yanagidani,
and also from a few other localities incooperation of Prof. T. MATSUMOTO,
Prof. Y. OTA and Mr. K. NU!\IANO. One
of us (1. H.) examined also many specimens of this species which had been
described by YARE, NAGAO and SH!i\IIZU(1926) and are now kept in the Tohoku
University. A few specimens from the
Kawaguchi, Yuasa, Shiroi and Ayukawa
formations are also available for study.
The result of our observation on these
specimens is reported in this paper.
One of us (1. H.) is responsible for thefurther note on the taxonomic positionof "Cyrena" nazwzanni.
Before going into description, we express our sincere thanks to Prof. Tatsuro!viATSUMOTO of the Kyushu University
for his kind guidance and supervisionof this manuscript. Acknowledgements
are also due to Prof. Yoshihisa OTA ofthe Fukuoka Gakugei University and
Mr. K6ichir6 NUMAi\O of the TanabeHigh School for their kind assistanc;; inthe laboratory and field works.
Systematic description

Family Neomiodontidae
Genus Protocyprina VOKES, 1946(=Amplziaraus VOKES, 19-16)
Type-species.-Astarte libanotica FRAAS,
1878, Aptian, Lebanon (original designation).
Diagnosis (emended).-Shell unusuallylarge for the Neomiodontidae, inequilateral, trigonally ovate or cuneiform.
moderately inflated: test thick especially in the gerontic stage; lunule weakly
impressed: escutcheon distinct: surface
commonly marked with Astarte-like concentric ribs in the juvenile stage but

116!tarn llA YAAJI and /sao NAKAI

lkuna

\

.. _/.

akaizu'~u1don1

Text-fig. 2. Map .showing the localities of Prolocyprina naumanniin the Katsuuragawa area of eastern Shikoku.

nearly smooth except· for somewhat
rugose growth-lines in the adult stage;
radial ornament and marginal crenulalions absent; umbo very prosogyrous;
hinge essentially similar to that of Eomiodon.. as. formulated:.
-~. AliiAllAI

3a 3b 5b
2 ·lb

PI
PI!

<:ardinal tooth 3b especially thick ; 5b
distinctly separated from nymph; lateral
teeth comparatively short in the adultstage; transverse crenulations on thelateral teeth, if present,. very weak;
pallial line simple but bent somewhat
abruptly beneath the posterior adductor
s·car; umbonal cavity comparatively
shallow.
Remarks.-ln a study of the Neomiodontidae CASEY (1955) regarded Protocyprina VoKES, 1946, as a subjectivesynonym of Eomiodon Cox, 1935. In
fact, Prolocyprina is similar to Eomiodon
in many characters. The type species
of l'rotocyprina, i.e . .-lstarte liban'otica
FRAAS, 1878, occurs from the Aptian
beds at .. Olive locality" of Lebanon.
The immature specimens of Protocyprina
libanolica are especially similar to somespecies of Eomiodon, such as E. fimbria/us (LYCETT) from the Bathonian ofEurope, not only in the internal structure but also in the external features.
The concentri.c sculpture on the surface
of immature shells (VOKES, 1946, pl. 5,
figs. •1. 5, 9) and also on the umbonal
area of mature shells (VOKES, 1946, pl.
5, figs. 2, 3, 6) reminds ~s that of many
species of Eomiodon. As to. the dentition no marked difference is recognized
between Eomiodon and Protocyprina, although the cardinal tooth 5b may be

4rn.

On a Lowe·r Cretaceou.H f'elecypod. ··Cyrena., naumanni·slightly stronger and the posterior lateral
teeth PI and PII may be proportionally·shorter in the latter than in the former.
We regard here, however, Protocyprina
as a distinct genus from Eomiodon invie\v of the following characters.
1) The maximum length of an adult·shell is only about 10-25 mm in Eomiodon
but frequently exceeds 70 mm in Protocyrina libanotica and "Cyrena" nau-manni.
2) The lunule is less clearly demarcated in Protocyprina than in Eomiodon.
3) The concentric sculpture in theadult stage is less prominent in Protocyprina than in Eomiodon.
VOKES (1946. p. 170-172) described thehinge structure of Protocyprina libanotica,
interpreting that the species belongs to
the Arcticidae. He compared the hingewith that of Cyprina ( =ArclicaJ islandica(LJ:>:NAEUS) from the north Atlantic andVenilicardia bifida (ZITTEL) from theUpper Cretaceous Gosau beds of Alps.
But the dentition of Arctica, Venilicardia
and other genera of the advanced Arcticidae is characterized by the presence ofthe nearly complete cardinal tooth 1, as
CASEY (1952) called such a state of dentition " cyj>rinoid ".
VOKES suggested
furthermore that Protocyprina might beconsidered to be ancestral to, or very
near the ancestral line of, Cyprina itself,
but from the above mentioned evidences
it is clear that Protocyprina is not directly
related to the Arcticidae of the present
sense. The ancestry of Arctica, we
think, should be sought in such genera
as Venilicardia STOLICZKA, 1871. in theUpper Cretaceous and Somarctica TAMURA, 1960. in the Upper jurassic.
Amphiaraus VOKES, 1946, was originally referred to the Astartidae witha query, but it is likewise referable
to the Neomiodontidae. CASEY assigned:its type-species, Amphiaraus seleniscus

117

VoKES, 19,16. from the Aptian of Leba·
non,. also to Eomiodon. The arrangement of the cardinal teeth agree wellwith that of Eomiodon and Protoc_V/>rina,
while the comparatively short· posterior
lateral teeth are quite identical withthose of Protocyprina libanotica. Since
the holotype of Amphiaraus seleniscus(ca. 28 mm long) is larger than normal
species of Eomiodon, it is better referable Protocyprina than to Eomiodon. We
treat here Amplziaraus VoKES . 1946 (p.
175) as a subjective synonym of Protocyprina VOKES, 1916 (p. 170) by page
preference.
Eomiodon appeared already in the
Hettangian of japan (HAYA:\11, 1958)
and flourished in the Bathonian-Purbeckian of N. 'N. Europe and Tethyan
province. A few· Cretaceous species
have been listed by CASEY (1955). butthey are mostly not typical for the
genus. Astarte sakawana KoBAYASHI
and SUZUKI, 1939, from the Lower Cretaceous of Japan is probably a memberof Eomiodon. but so far as we areaware, there is no other species of typical Eomiodon in the Cretaceous. Proto·
cyprina is known at present only fromthe Aptian of Lebanon and the Neocomian of japan. Judging from thestratigraphic occurrence and also fromthe resemblance between Eomiodon andimmature shells of ProtocJ•prina, thelatter was probably derived from theformer in early Cretaceous times.

Protocyprina naumanni (NEU!'IIAYR)
Pl. 13, figs. 1-3; Pl. H figs. 1-8;
Text-fig. 3

1890. Cyrena naumanni NEt;~JAYR, in NAu:\!A:-iN and XEu:-.JAYH, !Jenkschr. Math.Naturu:. Cl. Kaiser/. ilkad. Wiss .. Bd. 57,
p. 33. pl. 4, figs. 3. 4.

1890. Cyrena gravida NF.I:MAYR, in N.-\U!\1.-\=":'-l'ltaru HA.YA.MI and !sao NAKAI

118

and NEt:~IAYR, ibid .. Bd. 57, p. 34, pl.
4, fig. 2.
1890. Cyrena /itlwcardium NEl!~1AYR. in NAU·
MANN and NELJMAYR, Ibid., Bd. 57. p.
:~4. pl. 1. lig. I.
1926. Cynma naltmarmi. YABE, NAGAO andSIIIJ\fi7.U, Sci. Rep. Tohoku Imp. Univ ..
Ser. 2. Vol. 9, No. 3, p. 49, pl. 12, figs.
23. 24' 26, 29, 30. 31.
1926. Cyrena naumanni, YABE r.nd NAGAO.
Chikyu, Vol. 5. p. 434.
1927. Cyrena naumanni, YABE, Sci. Rep. Tohoku Imp. Univ., Ser. 2, Vol. 11. No. 1.
pl. 3, figs. Sa, b.
1947. Polymesoda (Jsodomella) naumanni, MATSU~IOTO.

Sci. Rep. Fac. Sci., Kyushu
Univ .. Geol .. Vol. 2. No. 1, p. 3, t(sted.
1949. Polymesoda (lsodomella) naumanni. SuZUKI, japan. jour. Geol. Geogr .. Vol. 21.
Nos. 1-4, p. 119. listed.
1952. Polymesoda (lsodomella) naumanni, MATsuMoTO and KANMERA, Guide bookfor the geological excursions. The
lower valley of the Kuma, p. 38, listed.
1954 [for 1953]. Polymesoda (Isodomella)naumarwi. MATSU~IOTO, Cret. System.
Japan. Islands, pp. 63, 74. 81. 85, llO.
listed.
non 1955. Polymesoda (lsodomella) rwumamzi.
YAMA<;IWA, jour. Osaka Gakugei Univ ..
No. 3, p. 47, pl. 1, figs. 5-15.
1956. Polymesoda(lsodomella)naumanni.
ONUKI, Explanatory text of the geologic map of lwate Prefecture, p. 145,
listed.
1963. "Cyrena" naumanni, HAYA!'.Il in MA·
TSt.:!o.IOTO (ed.). A survey of the fossils
from Japan illustrated in classicalmonographs. p. 34. pl. 52, figs. 1-4. (reproduction of original figures of C.
naumarwi, C. gravida and C. lithocardium)

Material.- The syntypes (NAUMA:-;N
and NEUMAYR, 1890, pl. 4. figs. 3, 4:
HAYAMI in MATSUI\IOTO, 1963, pl. 52,
figs. 3. 4). which are to be preserved
at Gcologisch-Palaontologische Abteilung
des Natur-historisch Museum, Wien, are

not accessible to us. They were collected at Yanagidani. Kamikatsu town
( ·. Menuki). Katsuura County, Tokushima
Prefecture. 24 specimens (GK. H6726GK. H6749) from the Katsuuragawa area
including the type locality (tviATSUMOTO.
0TA, NUl\IANO, HAY AMI and NAKAI coli.)
are preserved in the Kyushu University,
Seven other topotypes. which were illu·
strated by Y ABE, NAGAO and SHIMIZU(1926, pl. 12, figs. 6. 17, pl. 13. fig. 25, pl.
14, figs. 23, 26. 29, 31) and are now kept
in the Tohoku University, are also concerned with the description below.
Descriptioii.-Shell very large, equivalve. inequilateral, usually exceeding
70 mm in length in the adult stage. triangular-ovate in outline. more or lesslonger than high, moderately inflated;
test fairly thick especially in the gerontic stage; antero·dorsal margin relatively long, faintly concave in front ofumbo. passing gradually inlo anteroventral margin; postero-dorsal margin
strongly convex; siphonal margin not
clearly defined from postero-dorsal margin ; ventral margin broadly arcuate but
sometimes a little concave in its posterior
part; an indistinct carina extends fromumbo to the postero-ventral extremity ;umbo very prosogyrous. placed at about
one-fourth or one-third of shell-lengthfrom the anterior end; lunule moderate
in width, rather shallow. very weakly
defined ; escutcheon well demarcated byan angular ridge ; ligament external,
short but highly elevated above thedorsal margin; surface marked numerous
concentric lines of growth. which aresomewhat rugose and quite irregular inprominence: no prominent concentric ribson the umbonal region : hinge plate broad
especially in adult shells: dentition characterized by much modified lucinoid
cardinal teeth and corbiculoid elongated.
lateral teeth, as formulated:

493.

On a Lo wer Cret~ceous Pelecypod, "Cyrena" nau1nanni

Alii AI 3a 3b 5b PI
Ail
2 4b
PII '
3a c:>mparatively small, t ubercu lar, acline,
represented by a terminal thickening of
AIII; 2 fairly stout, highly elevated,prosocline, separa ted from Ail by a wide

119

interruption ; 3b especially brge, very
stout and broad; 4b moderately thick,obliquely elongated, very prosocline; 5bnarrow, short but di stinctly separated
from nymph; a nterior lateral teeth li nea rly elongated a long the antero-dorsal

T ext-fig. 3. Protocyprina naumanni (NEU:VIA YR)
l.

2.
3.
4.
5.
·6.

Rubber cast taken from a righ t internal mould (GK. H6749) x 1.5. [ See also Pl. 14, Fig. 5]
Rubber cast take n from a right in ternal mould (GK. H6747) x l. [ See also Pl. 14, Fig. 8]
Rubber cas t taken from a le ft internal mould (GK. H6745) x 1.5. [See a lso Pl. 14, Fi g. 3]
Rubber cast taken f rom a right inte rnal mould (GK. H6746) x l. [See a lso Pl. 14, Fig. 6]
Rubber cast taken from a left internal mould (GK. H6739) x l. [ See also Pl. 14, Fig. 2]
Ru bber cast taken from a lef t internal mould (GK. H6737) x l. [See a lso Pl. 14, Fi g. 7]

ltnru If!I YAAfl und lsno NilK/tl

1211

margin, but AI and Alii ill-defined frommargin of hinge plate ; posterior lateral
teeth PI and PI! remote from cardinalteeth. much weaker than anterior laterals,comparatively short in the adult stage;
Pill not defined: no prominent trans·-:._

verse crenulations on lateral teeth; adductor scars subovate, subequal in size;
pallial line abruptly bent beneath the posterior adductor scar, but never sinuate ;.
pedal scar not clearly marked: umbonal
cavity compar:ltively shallow.

A1easurements in 111111.Specimen
Both valves (G K. H6726)
Both valves (GK. H6727)
Left valve (GK. 1!6728.) :Both valves (GK. H6729)
Right valve (GK. H6730)
Both valves (GK. H6731)
Both valves (GK. H6732)
Right valve (GK. H673·l)
Left valve (GK. H6735)
Left in. mould (GK. II6737)
Right in mould (GK. H6738)
Left in. mould (GK. H6739)
Both valves (GK. H6740)
Right in. mould (GK. H6741)
Right in. mould (GK. H6742)
Left in. mould (GK. H6743)
Left in. mould (GK. H6745)
Right in. mould (GK. H6746)
Right in. mould (GK. H6747)
Right in. mould (GK. H6748)
Right in. mould (GK. II6749)

Obseruations and co111parisons.---'-ln addition to the 31 specimens above described. many specimens from the typeand other areas at hand .arereferable•1
to the present species. Most of these
specimens are more or less secondarily' deformed. and the ratio of length/height·apparently varies to a great extent.
l\lost specimens with two valves, jn
juxtaposition are crushed and secondarily depressed, and the thickness is generally much decreased. On the groundsof measurements of undeformed specimens. it is evident that the range ofthe intraspecific variation is fairly wide;
hence NEUMAYR (1890) previously con-

Length
85.5
78.0
61.0
59.0+
56.5
60.5
75.0
30.0
36.0
69.5+
36.0
50.0
56.0
21.0
41.0
37.0
28.0
46.0
4•1. 533.5
23.0

Height68.0
73.5
112.0+
46.0+
53.5
57.0
75.0
22.5
33.5
78.0
27.0
39.5
48.0
17.0
29.0
32.0
24.5
37.0
35.0
24.5
18.5

Thickness
31.0
24.5
13.0
25.0
13.0
28.5
28.0+
6.5
8.5
13.5
7.0
8.5
23.5
5.0
8.0
7.0
5.5
8.0
7.5
5.5
4.0

L/H
1. 26
l. 06
1.451.06
1. 06
1. 00
l. 33
1. 07
0.89+
1.33
1. 27
1. 17
l. 24
l. 41
1. 16
1.14
1.24
1. 27
l. 37
1. 24

sidered his material from Yanagidani to·be separable into three species. In oneof the syntypes (NAU:\IA~N and NEuMAYI<, 1890. pl. 4, fig. 3) and some ofthe present topotypes (GK. H6728, GK.
H6729) the ventral margin is slightly
concave, while it is broadly arcuate inother specimens. The prominence of theposterior carination and the position of
the umbo are also somewhat variable,
but it may be partly due to the differ·ent states of secondary deformation.
Beside the type area i.e. the Katsuuragawa valley, the present species occurs also from the Yatsushiro. Yuasa,
Sancln1 and Ojika areas. So far as we4.9:1.

On a /,ower· Cretaceons l'elec]IJwd. ··Cyrena" nawnanni

observed the present m:1terial. no marked morphological difference is discernible
between the groups of specimens fromone area to another. Although they- arevariable in the state of preservation andgenerally more strongly deformed than
the specimens from the type area, two
specimens(GK. H6750. GK. 116751) from theYuasa formation of the Yuasa area. one
specimen (GK. H6752) from the Kawaguchi formation of the Yatsushiro area.
one specimen (GK. H6753) and several
ones in the Tohoku University from the
Shiroi formation of the Sanchu area, andtwo ill-preserved moulds from the Ayukawa formation of the Ojika area arecertainly referable to l'rotocyprina naumanni in view of the similar external
and/or internal characters.
The immature shells of this species.
which are represented by several specimens (GK 116734. GK. 116741, GK. 1167,15.
GK. J-16749). show an Eomiodon-like internal structure. The disposition of the
cardinal teeth is essentially similar tothat of many Jurassic species of Eomiodon, although the anterior lateral
teeth are not so strongly curved inwards
as in Eomiodon. In some gerontic specimens (GK. H6737, etc.), however, thehinge plate is extraordinarily thickened,
the lateral teeth become somewhat obsolete, and the cardinal tooth 5b is pro·portionally much thickened. The hinge
structure in various ontogenetic stages
is well exhibited in the specimens GK.
116736, GK. 1-16737, GK. H6741. GK H67,12,
GK. H6746, GK. H6748, GK. H6749 (Textfig. 3) and also in the specimen IGPS
reg. no. 35153 (YABE, NAGAO and SHIMIZU, 1926. pl. 12, fig. 6) preserved in
the Tohoku University. In the specimens GK. 1-16726, GK 116727. GK H6731,
the opisthodetic external ligament is wellpreserved, as is usually so in other eyreooids from the Jurassic and Cretaceous

121

brackish-water sediments of japan.
It is probably a general tendency thatthe ratio of length/height decreases withgrowth. In most of the young specimens
the ratio is slightly larger than L20,
while in many adult specimens it scarely exceeds 1.10. The tendency is wellrecognizable also from the growth-lines
of one specimen.
The present species is closely related
to Protocypri n a lib an otic a (FRAAS. 1878}
from the Aptian of Lebanon (NOETLING,
1886: VOKES, 19•16; CASEY, 1955). because
they are similar in every essential character. The distinctly separated cardinal
tooth 5b and the much thickened 3bshow that they are equally distinguishable from Eomiodrm. The size of theadult specimens of P. liba11otica (ca. 80
mm in maximum length) is just comparable with that of the present species.
The Lebanon species is. however, different from the present one in the more
centrally placed umbo and the presenceof conspicuous concentric sculpture on
the umbonal surface.
We agree withY ABE. NAGAO and SHI·MIZU (1926) and other subsequent investigators in considering that the threenominate species of NEUMAYR (1890),
Cyrena naumanni, C. gravida and C.
Lithocardium, are actually conspecific;
the specific name of Cyre11a naumanni
is applicable on account of its pagepriority. Y ABE, NAGAO and SHL\!IZU(1926, p. 50) noted the presence of threecardinal teeth in each valve, regarding
the dentition of this species as cyrenoid.
However. as described above, the left
valve has only two cardinals 2 2-nd 4b.
the cardinal 1 is absent. and the hinge
structure is certainly a kind of Jucinoidtype.
Y A:'>! AGIW A (1955) interpreted .. Cyrena"
shiroiensis Y ABE and NAGAO in YABE,
NAGAO and Sll!l\IIZU (1926) to be a122

lta.1·u HAYAMJ and ]sao NAKAI

synonym of "Cyrena " naumanni, considering that the two species are hardly
separable as regards his material fromthe Lower Cretaceous of the Shima area.
But the syntypes of "Cyrena " shiroiensis (Y ABE, NAGAO and SHIMIZU, 1926,
pl. 14, figs. 4-6, 19, 20, 22, 25), from the
Shirai formation of the Sanchu area, areclearly distinguishable from the typical
specimens of Protocyprina naumanni inthe much smaller dimensions, the deeper
umbonal cavity, the presence of transverse crenulations on the side slopes of
the cardinal teeth, and the different disposition of the cardinal teeth of C. shiroiensis, as is well exhibited in the
hypotypes from the Yoshimo formationof the Shimonoseki area (KOBAY ASH!
and SuzuKI, 1939). These characters do
not agree with the diagnosis of any
known genus of the Neomiodontidae.
Although further studies are needed on
the taxonomic position of ··C." shiroieusis, it is evidently distinct from Proiocyprina naumanni in a generic level.
Y A~IAGIWA's specimens are probably referable to •· C." shiroiensis instead of P.
nauinarzni in view of the deep umbonal
cavity and small dimensions, although
their hinge structure is unknown indetail.
Occurrence.- Koch ian (approximately
lower Neocomian) and (?) Aritan (appro-

ximately upper Neocomian). Dark grey
shale of the Tatsukawa formation at
Hy. 5010, south of Yanagidani (typelocality) and at Hy. 5041, south of Shokuda, Kamikatsu town, Katsuura County,
Tokushima Prefecture. Weathered sandy
shale of the same formation at Hy. 5032,
near Tatsukawa, Katsuura town, thesame county, and at Nk. 5018, south ofNishioka, the same town. Above noted
localities are indicated in Text-fig. 2.
Black shale of the Kawaguchi formation
at a road-cut between Kawaguchi and
Shimofukami, Sakamoto town. Yatsushiro County, Kumamoto Prefecture~KANl\IERA coli.). Dark grey sandy shaleof the Yuasa formation at Tataki cape,south of Suhara, Yuasa town, Arita
County, Wakayama Prefecture (MATSUMOTO, 0TA and HAYAMI coli.). I3lackshale of the Shiroi formation at Bomckisawa, OhinaLa village, ivlinamisaku
County, Nagano Prefecture (YABI~ et al.
coli.). Grey sandy shale of the Ayukawa
formation at Kukunari, Ojika town, Ojika
County, Miyagi Prefecture (HAYAl\11 coli.).
Y ABE, NAGAO and SHIMIZU (1926) reported this species also from .. cyrenoid
beds " at Shirai and Hachimanzawa of
the eastern part of the Sanchu area inGumma Prefecture, where Aritan andl'vliyakoan deposits are distributed HIRA·YMIA et al. (1956) and some others re·

Explanation of Plate 13
Prolocyprina naumanni (NEe~IAYR) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . p. 117
Fig. L Bivalved specimen (GK. H6727) x 1. Tatsukawa formation at Hy. 5010. Yanagidani, Kamikatsu town, Katsuura County, Tokushima Pref. la: left valve, lb:
right valve.
Fig. 2. Right valve (GK. H6731) x 1. Loc. ditto.
Fig. 3. Bivalved specimen (GK. H6726) x 1. Loc. ditto. 3a: left valve, 3b: right vah·e,
3c: upper view.
All specimens illustrated are kept in the Department of Geology, Kyushu University.
Photos by I-IAYA:\11 and NAKAI.

H AYAMI and NAKA I:"Cyrena" naurnanni

Plate 13

4.9;J.

On a Luwer Cl'etaceous l)elecypod . .. Cyrena .. na:unanni

ported that "Cyrena" naumanni occurred also from certain brackish-water
beds in the Hanoura formation of the
Katsuuragawa area. Those occurrences,
however, are doubtful, because the pelecypod specimens from those localities
are certainly referable to the species
which are distinct from Protocyprinan azmzannr.
Further notes on the taxonomic positionof ·• Cyrena " naunuwni and theclassification of the~eomiodontidae

By ltaru IIAYA:\11
As has been precisely described above.
.. Cvrena" IWUIIWI!Ili is clearly different
fr0;11 any species of the Corbiculidae inthe hinge structure. All the species of
the Corbiculidac. including Polymcsoda
RAFII'\ESQUE, 1820. have in each valve
three cardinal teeth. of which the central cardinal tooth 1 is well developed.
In "Cyrena" naumanni. however. thistooth is absent, the cardinal tooth 2 isnever differentiated into 2a and 2b. andthe weak cardinal tooth 5b is clearly
demarcated from the nymph. In thedisposition of the cardinal and lateral
teeth and also in external features, thisspecies is especially similar to .-lstarte
tibanotica fi{AAS. 1878. from the Aptianof Lebanon. which is the type-species ofProtocyprina VoKES, 19·16. It is considered here the two species are congeneric. In other words .. Cyrena" naumanni is assigned to Prolocyprina.
The dentition of Protocyprina is notof cvrenoid but of lucinoid type. The
elongated lateral teeth may remind me
those of corbiculids, but in the general
hinge structure it is best referred to the
Neomiodontidae defined by CASEY (1955).

l::~:J

It is here sugge:;ted that the Neomiodontidae are sep:1rable into two phylagenetical suites: one is the group of
Neomiodon FISCHER, 1887 (=.\liodon
SANDBERGER. 1871. non DUMf~RIL, 1859,
nee CARPENTER, 1865: ?=Protomiodon
Al\DERSON and Cox. 1948), including
Myrene CASEY, 1955 and Crenolrapezium
HAY A:\11, 1958, and the other is the groupof Eomiodon Cox, 1935 (non CIIAV A:'\,
1936), including Pseudasaphis MATSU·:\lOTO, 1938. Protocyprina VOKES, 1946,
and Coslocyrena MATSUMOTO and KAN:\IER:\, 1952 ~l'viS*J.
The group of Neomiodon is generally
characterized by the thin test. the moreor less conspicuously carin3te shell. theabsence of a well defined lunule. the undeveloped cardinal tooth 5b, the well de·veloped transverse crcnulations on thelateral teeth and the smoothly arcuatepallial line. In many characters thisgroup is fairly similar to J~'otrapezium
DouviLLE, 1913, a primitive genus of
the Arcticidae from the marine Lower
jurassic. The group of Eomiodon, on
the contrary, shows thick test, a weak
postero-ventral carina, a clearly defined
lunule and a well developed cardinal
tooth 5b. The transverse crenulations
on the lateral teeth are less distinctly
developed. The pallial line is generally
abruptly bent beneath the posterior adductor scar in the group of Eomiodon.
The surface, especially the umbonal
region, is commonly marked with concentric ribs and rarely also with radial
riblets. In some characters the group of
Eomiodon is more similar to the Astartidae than to the Arcticidac. Although
the Neomiodontidae have been referredto the Arcticacea, the two groups were
probably derived independently from* The diagnosis of this genu:; will be given
on another occasion.

124!tarn 1-!A.J'AMI and !sao NA!Cll

two m::!rine heterodont pelecypods which
are unrelated with e:1ch other. If the
Neomiodontidae had dual origin, they
could be separated into two subfamilies
or even into two families.
References
CASEY. Raymond (1952): Some genera andsubgenera, mainly new, of Mesozoic
heterodont lamellibranchs. Proc. Ma/ac.
Soc. London, 29. 121-176.
- - (1955): The Neomiodontidae. a new
family of the Arcticacea (Pelecypoda).
Ibid. 31. 208 -222. pl. 11.
HAYA:>.ll, Itaru (1958):
A re,·iew of theso-called Liassic -- cyrenoids" in Japan.
japan. jour. Ceo/. Ceogr., 29. (1-3). 11-27.
pis. 2. 3.
HIRAYA\JA, Takeshi et al. (1956): Explanatory text of the geologic map of Kenzan(I /75.000). 52pp. Tokushima Pref. (injapanese)
KEEN, A. Myra (1958): Sea shells of tropicalwest .·lmerica. 62-1 pp.. 10 pis. Stanford
Univ.
KOBAYASHI, Teiichi and SliZUKI, K6iti (1939):
The brackish Wealden fauna of the Yoshirno beds in Prov. Nagato, Japan.
japan. jour. Ceo/. Ceogr .. 16. (3-'1). 21322,1. pis. 13. H.

MATSUMOTO, Tatsuro (195-l): The Cretaceous System in the japanese Islands. xiY+32-l pp., 36 pis. Japan. Soc. Promotion
Sci. Res .. Tokyo. [for 1953]- - (1963. ed.): A survey of tire fossils fromjapan illustrated in cl!lSS.~~a/ monographs.
57 pp., 68 pis. Palaeont. Soc. japan. 25th
Anniv. Volume.
MATSU\JOTO, Tatsuro and KA?':<.Il::RA, Kametoshi (1952) : Guide book for geologicalexcursions. The lou•er valley of lire Kuma.
71 pp., 6 maps. Dept. Geol., Kyushu UniY.
(in Japanese)
NAUMANI". E. and NEUMAYR. M. (1890): Zur
Geologie und Palaontologie von Japan.
Denkschr. Kaiser/. Akad. IViss.. Mati!.Naturw. C/., 57. 1--41. pis. 1-5.
NoF.TLII"G, Fritz (1886): Entwurf einer
Gliederung der Kreide-formation in Syrien und PaHistina. Zeitschr. deut. geo/.
Gesell., 38. 824-875. pis. 2•1-27.
O~uKr. Yoshio (1956):
Explanatory text ofthe geologic map of !wale Prefecture(1 I 100.000). The geology of the Kitakami mountains. 189 pp. Iwate Pref.
(in Japanese)
SuzuKI, K6iti (1949): Development of thefossil non-marine molluscan faunas ineastern Asia. japa11. jour. Ceo/. Ceogr .•21' (1-4), 91-133.
VoKES, Ilarold Ernest (1946): Contributions
to the paleontology of the Lebanon

Explanation of Plate 14
Prolocyprina lllll111la1111i (NEUJIIA YR) . . . . .
. ............ p. 117
Fig. 1. Left valve (GK. H6728) x 1. Tatsukawa formation at Hy. 5010. Yanagidani.
Kamikatsu town. Katsuura County. Tokushirna Pref.
Fig. 2. Left internal mould (GK. I-16739) x 1. Loc. ditto.
Fig. 3. Left internal mould (GK. H6745) x 1.5. Loc. ditto.
Fig. 4. Right valve (GK. H6740) x l. Loc. ditto.
Fig. 5. Right internal mould (GK. H6749) x 1.5. Tatsukawa formation at Nk. 5018,
south of Nishioka. Katsuura town. Katsuura County. Tokushima Pref.
Fig. 6. Right internal mouth (GK. 1-16746) x 1. Loc. same as Fig. 1.
Fig. 7. Obliquely compressed left internal mould (GK. H6737) x 1. Loc. same as Fig. 1.
Fig. 8. Right internal mould (GK. H6747) x 1. Loc. same as Fig. 5.

All specimens illustrated are kept in the Department of Geology,_ Kyushu University.
Photos by IIAYAMI and NAKAI.

HAYAMI and NAKAI :1"Cyrena" naumanni

Plate 14

49.1.

( >11 a Lower Cretaceous Pelecypod. ··Cyrena.,. nanmcmni

mountains. Republic of Lebanon. Part
3. The pelecypod fauna of the "Oli1·e
locality" (Aptian) at Abeih. Bull . .:tmerican Museum Nat. His/ .. 87. (3). 143-215,
pis. 1-10.
YABE. Hisakatsu. NAGAo. Takumi and Slll~llzL·. Saburo (1926):
Cretaceous l\lol·lusca from the Sanchu graben in the125-

Kwanto mountainland. Sci. Nep. Tohoku
Imp. Univ .. [2], 9. (2). 33-76. pis. 12-15.
YA~!AGIW.'\, Nobuo (1955): Cretaceous Mollusca from the Shima peninsula, japan.
jour. Osaka Gakugei Unit•.. (3). 43-56,
pis. 1. 2. (in Japanese with English re·surue)--- ----------------Ayukawa
Bomekisawa
Ilachi ma nsa wa
Kamikatsu town
Katsuura town
Kawaguchi
Kukunari-hamaMonobegawa
Nishioka
Ohinata 1•illage~Jll:f.-;l~iR/\ fl iR
J:Jmii!J

Mi i!li II!J0
Jll
i- :IL ~~J.I $
jl_§

Jll
(ii\j

:kBf,','Jf:t

Shima
Shimofukami
ShiroiSbokudaSuharaTataki
Tatsukawa
Yanagidani
Yatsushiro
Yuasa

±

•C.•

,.

Jf<

*

'f i~
;Itt'l

D.ft

Ill

li§

)Jj(

9liJ
'Sr.

~

~p

.fj-

1\

1\::

/},}

(~

Jll

Trans. Proc. Palaeont. Soc. Japan, N. S., No. 591 pp. 126-1-12. pis. 15-16, S.:pt. 20, 1965

-194.

CRETACEOUS ECHINOIDS FROM THE SANCHU GRABEN,
CENTRAL JAPAN*
KEISAKU TANAKA
Geological Survey of Japan

Introduction and Acknowledgements

The Cretaceous deposits in the Sanchu
graben. about 100 km northwest of Tokyo,
have been hitherto investigated by many
persons from the standpoint of strati·
graphy and paleontology. Nevertheless,the detailed geological map publishedstill covers only the eastern part of thearea ; and moreover the paleontologicalworks have been done chiefly on themolluscan fossils alone. As to the echinoids which are very subordinate constituents among the Cretaceous fauna inthis area, only a few species have beenreported by Y. YABE and others ll955),
F. ARAI and others (1958), and K. T AKEI(1962) without paleontologic descriptions.
Such being the case. for the purpose ofa more complete collection of specimens
together with examination of the stratigraphic occurrence, the writer visit~dthe Sanchu graben in 1953, and agam m
1958. !'vfeanwhile some other investigators' collections from this area were
·offered to the writer.
Thus, many
specimens from the Lower Cretaceousin the Sanchu graben were ready to hts
hand. As the result of the study, di:;• Received May 5, 1965; read Sept. 2:{, 1961.

criminated among them were six genera
and eight species ; one of these species
was already described by the writer andhis co-worker under the name of Aphelaster serotinus TANAKA and SHIBATA,
and two others are new to science.
Some of the species here described arefound also in the Lower Cretaceous ofseveral other areas in the Outer side ofSouthwest Japan. So, for the descriptionof such species here complementally
dealt with are materials obtained fromthe Barremian Arita formation in the
Yuasa area in the western pan of theKii Peninsula.
The writer expresses his cordial thanks
to the following persons: Dr. Masahiro
OKUBO of the Geological Institute, University of Tokyo for his much help in
the collecting of materials and photographing: .Mr. Yukio YABE of the Japanese Information Center of Science andTechnology and ~Jr. Kensaku T AKEI of
the Chichibu Natural Science !\luseum
for their kind offer of materials and information on the stratigraphy; Dr. Noboru YAJ\IASHITA of the Geological Institute, University of Tokyo and Mr. !v1an·
kichi HOI{IGUCHI of the Department ofEarth Science, Saitama University for
12(i

494.

their kind offer of materials; Mr. Yoshio
MASAI of the Geological Survey of Japanfor the photographing.

Stratigraphical Note

The Cretaceous deposits in the Sanchu
graben. 40 km long and 2-3.5 km broad.
are in fault relation to the Paleozoic on
both the northern and southern sides.
being in a direction subparallel to thegeneral trend of the Paleozoic. Theyshow a synclinorium structure complicated by numerous longitudinal andtransversal faults. According to T AKEI(1963), the stratigraphic succession in theeastern part of the area is as follows indescending order.
Sanyama formation (lower part of the Upper
Cretaceous) : About 500 m thick. begining with basal conglomerate which. inturn. is succeeded by shale and subordinate sandstone. Marine fossils are sporadic.
~--

127

C1·etaceous echinoids

Unconformity

Sebayashi formation (Aptian-Albian): Less
than 600 m thick. ~.:om posed of arkose
sandstone in the lower and alternationof sandstone and shale in the upper.
Molluscan remains. chiefly of brackish
origin are sporadic and a plant bed isfound in the lower.
lshido formation (Neocomian): About 400 m
thick, begining with conglomerate andcomposed mainly of sandy shale or siltstone. :\Iarine molluscan fossils such as
ammonites, trigonians and other bivalvesoccur in abundance. Brackish shells andplant remains are also common in certain
horizons.

The Ishido formation is to be corre·
lated to the Hauterivian and Barremianfrom the ammonite assemblages.

Fossil Localities

Most of the materials here dealt with
were collected from the Ishido formation. and only a few of them from thepresumed Ishido formation. Their localities are as follows (Fig. 1).
Loc. 1 :-About 1.1 km south of Hikage. Ogano-cho. Chichibu-gun. Saitama Prefecture:dark gray, massive. sandy siltstone in thelower part of the Ishido formation: echinoids scarce.
Loc. 2 :-About 800 m northwest of Sebayashi.
Nakazato-mura. Tano-gun, Gumma Prefecture; dark gray. massive. sandy siltstone in the lower part of the Ishido
formation : echinoids sporadic.
Loc. 3 :-About 500 m north of Myoke. Nakazato-mura, Tano-gun, Gumma Prefecture:dark gray, massive. sandy siltstone in
the lower part of the lshido formation:echinoids scarce.
Loc. 4 :-About 600 m north of Shiroi. Uenomura. Tano-gun. Gumma Prefecture:dark gray, massive, silty fine-grainedsandstone to sandy siltstone in the lower
part of the Ishido formation: echinoids
sporadic.
Loc. 5 :-About 2.5 km northwest of Shiroi.
Ueoo-mura. Tano-gun, Gumma Prefecture: dark gray. massive, silty finegrained sandstone to sandy siltstone in
the lower part of the lshido formation~echinoids common in some laminae.
Loc. 6 :-Upper course of the Honya. Minamimaki-cho. Shigaraki-gun. Gumma Prefecture; dark gray siltstone in the lower
part of the Ishido formation : echinoids.
scarce.
Loc. 7 :-lshido. Saku-cho. Minamisaku-gun,
Nagano Prefecture; dark gray, rather
massive siltstone in the lower parl of
the Ishido formation: echinoids sporadic.
Loc. 8 :-Lower course of the Onozawa. Sakucho, Minamisaku-gun, Nagano Prefecture:bluish gray. massive. medium-grainedsandstone in the presumed Ishido formation: echinoids scarce.

Keisaku TANAK.~l128

Fig. 1. Map showing the fossil localities. 1-8. fossil localities; 9. Kawarazawa; 10,Kanna river; 11, Kagahara; 12, Shiroi: 13, Jukkoku-toge. Inset .is a map of Kwanto, indi·
eating the Cretaceous outcrop in the Sanchu graben.

Echinoids occur scarcely also in the
Sanyama formation. But they are not.dealt with in this paper.

Description of Species
Order Cassiduloida DUNCAN
Suborder Cassidulina DELAGE
and HEROUARDFamily Clypeidae LA!\IBERT, 1898
Genus Pygurus L. AGASSIZ, 1839
Subgenus Pygurus (s. s.) L. AGASSIZ
Pygurus (Pygurus) complanatus n. sp.
Pl. 15, figs. la-c, 2a-c

Type specimens :-Holotype, GSJ. 6090;
paratype. GSJ. 6091.
Description:- Test small, subovate.
low, slightly longer than wide, widest
well behind the center, rounded in front.
lacking the anterior notch, nearly straightin the postero-lateral margins, slightly
produced behind. Adapical surface broad·ly convex. highest somewhat behind thecenter, steeper in front than behind.
rather acute at the ambitus; adoral

surface concave around the peristome,
somewhat pulvinate, less strongly inflated in the antero-lateral interambulacra
than in the others. Apical system some~what in front, small, with four genital
pores and a large central madreporite.
Ambulacra all similar, superficial,petaloid ; petals lanceolate, closed apically, slightly open distally, extending
almost to the ambitus; anterior petal
shorter, narrower than the others; anterior paired petals widest. diverging at
an angle of 120° to 130° ; posterior paired petals longest, diverging at an angle
approximating 60°. Poriferous zones
narrower than the interporiferous; poresconjugate, outer pores long slit-like, innerpores small, round to oval in the petaloid
part; pore pairs minute, rounded, obliquely set near the ambitus. Ambulacraon the adoral surface lodged in distinct
furrows.
Peristome somewhat in front, directly
under the apical system; pentagonal,
sunken ; phyllodes short, widened, depressed ; bourrelets conspicuous, elongated.
Periproct transversely oval.
inframarginal. not visible from above.
Tubercles small, perforate, crowded,
larger on adoral surface than on adapical surface.

494.

Cretaceous eehinoids

Measurements (in mm.) :-~ _\ Gs]~6ogo 1Gsj 6091
LengthWidth
HeightI
1Distance of apex from 1
the anterior end

21.2
Hl. 0
7. 5

19.7
\6.6
6. 1

8.9

8. 4

Remarks:-- The para type (Pl. 15, figs.
2a-c) shows a slightly more elongatedoutline than the holotype (Pl. 15, figs.
la-c) which represents the general formof the test. According to KIER's classi·
fication of the genus Pygurus (1962), thepresent species is to be placed in thesubgenus Pygurus. This species is clearly
distinguished from the Japanese known
species. Pygurus (Pygurus) asiaticus ToKUNAGA*. The latter has a tumid test,
a distinct anterior notch and a large
posterior rostrum. This new species re·sembles to some extent Pygurus (Pygurus)
impar GAUTHIER from the Upper Neo·comian of Algeria, although in the latterfeatures of the posterior part of test is
unknown. However, Pygurus (Pygurus)
complanatus differs from P. (P.) impar
in having shorter. narrower and more
tapering petals. The species hue de·scribed is furthermore easily distinguish·
able from Pygurus (Pygurus) monlmollini(AGASSIZ) from the rvliddle Neocomianof France and Switzerland. In /'. (P.)
montmollini the test is higher, distinctly
notched in front and largely rostrated
behind.
Occurrence :-Loc. 8, presumed lshido
formation. medium-grained sandstone,• Although this species was collected fromthe presumed Cretaceous strata in the south·
ern part of Shikoku. it exact horizon is still
unknown. The horizon was misled lo be the
Cenomanian in the Essai de nomenclature
raison nee.

129

Lower Cretaceous (GSJ. 6090, 6091, 6125,
6126. coli. by Y. Y ABE: GSJ. 6106, coli.
by K. TANAKA and Y. YABE).
Order Spatangoida L. AGASSIZ
Suborder ~vleridosternata (Lovf;;N)~v[ORTENSE:\

Family Holasteridae ZITTEL, 1879
emend. LA!\IBERT. 1917
Subfamily Holasterinae 1loRTEl'\SES. 1950
Genus Pseudholasler PoMEL, 1833
Pseudholaster n. sp. (?)
Pl. 15. figs. 3a-d. 4a-c: Text.figs. 2a-b

Descriptioll :-Test medium-sized, cor·date. nearly as \vide as long, widest alittle in front of the midpoint. contract·
ed behind; adapical surface rather fiattopped, highest on the margin of theanterior sulcus somewhat in front of theapical system. sloping abruptly in front,
truncated bchined: posterior truncatedsurface slightly concave. thus the pos·terior margin showing a shallow sinus;
adoral surface slightly convex. Apicalsystem somewhat in front. elongated,
the length about three times the width ;apical system. though its detailed structure being not observable. probablyintercalary type because the anterior
paired ambulacra and the posterior are
somewhat distant from each other at

--

-

#

- - 2a-- --- - 2b

Figs. 2a. b. Pseudholaster n. sp. ( ?).
Pore pairs in the left anterior paired
ambulacra (2a) and left posterior paired
ambulacra (2b). x6.· (GSJ. 60-16).

130

Keisaku TANAKA

the apex. Anterior sulcus deep, rather
short, increasing in width and depth to·ward the ambitus, forming a distinct
anterior notch. bordered by sharp keel·
like elevations on both sides. extending
to the peristome as a less distinct grooveon the adoral surface.
Anterior ambulacrum lodged in the
deep anterior sulcus, shortest, not peta·
loid ; poriferous zones much narrower
than half the width of the interporifer·
ous zones; pores similar, smaller. oval.
closely set, transverse. Paired ambulacra
open distally. superficial. subpetaloid; anterior ambulacra slightly flexuous, wider
th:w the posterior ambulacra which arestraight: pores opposite, not conjugate.
In the anterior paired ambulacra. anteri·or poriferous zones much narrower thanthe posterior, nearly half the width ofthe latter; interporiferous zones some·what narrower than the posterior zones.
Pores in the anterior zones elongatedoval. opposite, rather near together. Pos·
terior zones composed of longer slit·likeouter pores and shorter slit-like innerpores; pores of each pair opposite, wide·
ly set. In the posterior paired ambula·era, two poriferous zones less unequal incomparison with those of the anterior
paired ambulacra; anterior poriferous
zones narrower than the posterior ; inter·
poriferous zones somewhat narrower
than the posterior poriferous zones.
Pores in the anterior zones elongatedoval, opposite, rather closely set; poresin the posterior zones slit-like, opposite.
widely set, a little longer in the outerrow than in the inner.
Peristome semicircular. deep, situatedat about one-fourth from anterior end,
lying in the recurved end of the anteriorsulcus; plastron meridosternous. Peri·
proct high up on the posterior truncatedsurf::!ce which is concave, longitudinallyelongated oval. Tubercles small, similar-

sized, more closely spaced on plastronthan elsewhere. No fascicles.

Measurements (in mm.) :GSJ. 6050

26.8
26.8

LengthWidth
Height13.8

Distance of apex fromthe anterior end

Remarks:- The

10.9

specimenregisteredthoughlacking about half of the anterior marginal part of the test, is regarded as
showing the general form of the test in
the present species. The specimens at
hand are fairly close to Pseudholasterbaconicus SZORENYI from the Albian andCenomanian of Hungary in general fea·tures of the test. But there is a minor
but distinct difference between the two.
In P. baconicus tubercles are larger on
the margin of the adoral surface and onthat of the plastron than elsewhere. The
present form is distinguished from Ps£'Ud·
holaster bicarinatus (AGASSIZ) from the
Cenomanian of France in many respects.
In the former, the test is not arcuate
but rounded at the ambitus and the apical system is somewhat fonvard, thus
the anterior sulcus is shorter than in thelatter species. In P. bicarinatus, moreover. the posterior interambulacral areaon the adapical surface is elevated in
the form of carina. To sum up, thespecies here described probably repre·
sents a new species. The establishmentof this new species is, however, sus·pended until more specimens are obtained. The occurrence of Pseudholaste1·
from the Upper Neocomian of Japanrequires correction of the stratigraphic
distribution of this genus.
GS]. 6050 (Pl. 15, figs. 4a-c).

494.

Cretaceous echinoids

Occurrence :-Loc. 5, Ishida formation,
silty fine-grained sandstone to sandy
siltstone, Neocomian (GSJ. 6044-6050,
6129, coli. by K. TAN AKA and M.

~
~~
3a

OKUBO).

Suborder Amphisternata (LOYts).iVIORTENSE:\
Family Toxasteridae LA~IBERT. 1920
Genus Toxaster L. AGASSIZ, 1840

Toxaster .~anchuensis n. sp.
Pl. 15. figs 5a-b. 6a-b: Pl. 16, figs.
Ia -c. 2a-c; Text-figs. 3a-c

Type specimens :-Holotype, GSj. 6124:
paratypes. GSj. 60,11, 6042, 6110.
Description:- Test medium-sized, cordate. widest somewhat in front of the
midpoint. not greatly contracted behind ;adapical surface inflated. rather flattopped. highest at the apical system.
truncated behind; adoral surface nearly
ftattish. Apical system some\vhat infront of the midpoint. with four genital
pores. ethmophract.
Anterior sulcus
rather shallow. becoming wider. muchshallower tow·ard the frontal margin. extending to the pcristome: anterior notchrather indistinct.
Anterior ambulacrum depressed throughout the way, somewhat shorter, wider
than the paired ambulacra; poriferous
zones much narrower than the interporiferous zones. somewhat less than half
the width of the latter in the middle
part. widest near the middle, tapering
toward the ambitus and apical system.
Pores in the middle part oval to elongated oval. near together; outer poresnearly transverse or slightly oblique.
inner pores oblique; pores in the proximal and distal parts smaller, oval : poresnear the ambitus minute. round. oblique-Figs. 3a-c. Toxaster sa11chuensis n. sp.
3a. Anterior ambulacrum. x6. 3b. Left
anterior paired ambulacra. x6. 3c. Left
posterior paired am hulacra. x 6. (GSJ.
6124).

ly set. near the anterior outer corner of
ambulacral plates; pores of each pair
not separated by a granule. Paired ambulacra unequal. open distally, slightly
sunken, subpetaloid; petaloid part longer
in the anterior paired ambul::cra than in
the posterior. Anterior paired ambulacraslightly shorter. wider than the posterior
ambulacra. diverging at an angle approximating 110°. slightly flexuous; petaloid
part about two-thirds the way to themargin; poriferous zones somewhat unequal, anterior zones narrower than theposterior zones. Pores in the anterior
poriferous zones composed of short slit·
like outer pores and elongated onll innerpores. pores of each pair opposite, rather
widely set; pores in the posterior zones
slit-like. opposite. widely set, outer pores
longer than inner pores, acuminated inward. Pores in the distal part diminishing in length, becoming closer together;pores near the ambitus minute. almost
circular. near together. obliquely set. near
the anterior outer corner of ambulacral
plates. lnterporiferous zones somewhat
narrower than the posterior pori ferous
zones. Posterior paired ambulacra nearly straight. diverging at an angle approximating 60' ; petaloid part shorter .thanthat of the anterior ambulacra. about

Ke·isak1t 'TANAKtl

1 ·~·)~_,_

half the way to the margin, somewhat·closed at the end, composed of two equal
poriferous zones. Poriferous zones nearly equal to the interporiferous zones inwidth ; pores elongated, opposite, widelyset, outer pores longer than inner pores,
slit-like; features of the pores in the
distal part and near the ambitus similar
to the case of the anterior paired ambulacra.
Peristome subpentagonal, somewhat
transverse, near the anterior fourth tofifth, shallowly sunl<en; plastron amphisternous. Periproct longitudinally oval,
pointed at both ends, high up on theposterior truncated surface, visible fromabove. Tubercles small, perforate, crenulate. rather cro\vded near the ambitus
and on the plastron, rather sparsely
spaced on the remainder; interporiferous
zones of all the ambulacra dotted withmuch smaller tubercles; numerous microscopic granules between tubercles. No
fascioles.
Afeasurements (in mm.) :GSJ. 6041 GSJ. 6042
LengthWidth
HeightDistance of apex fromthe anterior end

27.2
22.8
12.5

22.4
21.0

13.5

12.2

11.2

The largest specimen reaches about 44
mm. in length.
Remarks:-The general form of thetest is well represented by one of theparatypes (GSJ. 6042; Pl. 16, figs. la-c),although this paratype is of small size,
probably an immature form. The present species resembles Toxaster gibbus
AGASSIZ from the Barremian and Aptian·of the Circum-Mediterranean region andT. peroni LAMBERT from the Neocomianof lVIorocco in the features of pore pairs
in the anterior ambulacrum, the depressedpaired ambulacra and the anteriorly eccentric position of the apical system.
But in T. gibbus the test is more inflated and the petals are longer than in T.
sanchuensis, and moreover the interporiferous zones of the paired petals haveno tubercles. T. sanchuensis is distinguished from T. peroni. which has tubercles in the interporiferous zones of thepaired petals like the former species, by
its much narrower petals. This new
species is similar also to Toxaster collegnoi (SIS'>IO!\DA) from the Aptian of
the Circum·.\elediterranean region as far
as the features of pores pairs in theanterior petal and the depressed paired
petals are concerned. However. theformer differs from the latter in having
narrower anterior sulcus and less flexuous
anterior paired petals. Furthermore. in
T. collegnoi the posterior interambulacralarea on the adapical surface has a slightly
carina-like elevation, while such is not
the case in T. sanchuensis. Toxaslet sanchuensis is clearly distinguished from T.
retusus (LA'.IA[{CK) from the Hauterivian
of Europe and the Hauterivio-Barremianof North Africa. In the former the apical system is anteriorly eccentric andthe anterior sulcus becomes much shal·
lower at the ambitus, while in the latterthe apical system is backward and theanterior sulcus is considerably deep at
the frontal margin. 1\'loreover, in T.
retusus the pores of each pair in theposterior poriferous zones of the paired
petals are separated by a granule.
Occurrence :-Loc. 2, Ishida formation,
sandy siltstone, Neocomian (GS]. 6107,
coli. by K. T A~AKA and Y. Y ABE); loc.
4, Ishida formation. silty fine-grainedsandstone to sandy siltstone, Neocomian(GSJ. 6130, coli. by K. TAKE!); Joe. 5.
Ishida formation, silty fine-grained sand-4.94.

1 •)•.}

Cretaceous ech-inoids

stone to sandy siltstone, Neocomian (GSJ.
6041-6043, coli. by K. TANAKA and !vl.
OKUBO; GSJ. 6110-6113, 6118, coli. by K.
TANAKA and Y. YABE; GSJ. 6124. coli.
by N. ·YAMASHITA: GSJ. 6130, coli. by
Y. YABE); Joe. 6, lshido formation, siltstone, Neocomian (GS]. 6059, coiL by Y.
Y ABE). Furthermore, a specimen probably identical with this species was obtained from the Barremian Arita formation in the Yuasa area (GSJ. 6035. coli.
by K. TA::-IAKA).
Genus Aphelasler LAJ\tnERT. 1920•_)•_)

anterior sulcus just in front of the apicalsystem, sloping gently forward, more
steeply behind, truncated behind; adoral
surface rather flat, deeply depressedaround the peristome, somewhat inflated
in the posterior interambulacral area.
Apical system very eccentric behind,near the posterior fourth; genital poresfour in number. Anterior sulcus deep.
very long, about three-fourths the lengthof the test, somewhat constricted andshallower just back of the anterior margin. biconvex, with sides nearly straight,
extending to the peristome; anterior
notch distinct .

.4phelaster serotinus TANAKA

and SHIBATA
1961. APhelaster serotinus TANAKA and SIII·
BATA. Trans. Proc. Pal. Soc. japan,
N. S.. No. 42, p. 68-72, pl. 10, figs. I -6.
text-figs. 1. 2.

Occurrence :-Loc. 7, Ishido formation.
siltstone. Neocomian (GSJ. 6092. 6093.
6095, 6096, coli. by Y. Y ABE).

%I~~::~:~:=::-=-=-~~'-'------=_. 4b
1

Genus Heteraster D'OHBIGNY. 1853.--·-(;; } -----....__

Heteraster macroholcus (NISIY :\\IAJ
Pl. 16. figs. 3, Ja-b: Text-figs. 4a-d
1950. 1Vashitaster (?) macrolwlcus NisiYA~IA,
Short Papers IGPS. No. 1, p. 45. figs.
4-7.
1954. Washitasler macroholcus. T A:"AKA and
0Kt:Bo. jour. Geol. Soc. japan. Vol. 60.
No. 705. p. 221, pl. 7, figs. 1. 2, textfigs. 5. 7.
1954. lVashitaster barremicus, T.·\:->AKA andOKUBO, Ibid., Vol. 60, No. 705, p. 220.
pl. 7, fig. 3. text-fig. 7.

Description:- Test large. ovate, rather
low, widest near the midpoint. not greatly
contracted behind: adapical surface gent·
ly arched. highest on the margin of the-~~-~'>---~-~( =Ena/laster D'0RBIG:>lY, 1853)-'--~-~)4c4a-d.
Heteraster macroholcus(NisiYA:\IA).
4a. Anterior ambulacrum.
x 5.5. 4b, Right anterior paired ambulacra, x 5.5. •lc. Right posterior paired
ambulacra. x5.5. (GSJ. 6128. Arita formation). 4d, Plastron, x 0.75. (GSJ. 6002.
Arita formation).
Figs.

Anterior ambulacrum longest, lodged
in the deep anterior sulcus, widest midway between the apical system and thefrontal margin: poriferous zones somewhat narrower than the interporiferous.
Pores in the main part of the petaliferous part very unequal, opposite, rather
close together ; in the outer row poresslit-like, acuminated inward, several

134

Keisa/m LL\'AKA

longer pores irregularly alternating with
one shorter pore; in the inner row poresround to oval. pores opposite shorter
outer ones slightly smaller. somewhat
inward. thus pore pairs lining up in
three (or better to say rather four) files.
Pores in the proximal part becoming
less unequal. inner pores round. outerpores oval to elongated oval. Paired
ambulacra very unequal in length. :::uper·
ficial, flexuous. subpetaloid.
Anterior
paired ambulacra much longer than theposterior. diverging at an angle appro·
ximating 120• then turn forwards andlaterally, angle between mid-line of eachpetal about 70•. and then diverge laterally
and cross the ambitus far anteriorly;
poriferous zones very unequal. anteriorzones much narrower than the posteriorzones. Pores of the anterior zones ovalin the outer row. round to oval in the
inner row. opposite. near together; poresof the posterior zones elongated oval in
the inner row, slit·like in the outer row,
opposite. r<!ther close together. lnterpori·fcrous zones nearly equal to the posterior
poriferous zones in width, enlarging to·ward the extremity. which are open.
Posterior paired ambulacra shortest,
broad, bulging in the center, diverging
at an angle approximating 130" andthen converge laterally ; poriferous zones
very unequal, anterior zones much narrower than the posterior. Anterior zones
composed of elongated oval outer pores
and oval inner pores, pores of each pair
opposite, near together. Pores in theposterior zones elongated oval in the
inner row. slit-like in the outer row.
opposite. rather close together. Inter·
pori ferous zones nearly equal to theposterior poriferous zones in width, enlarging toward the extremity. which are
open.
Peristome transversely oval, deeply
sunken. far anteriorly. ncar the anterior

fourth, lying in the recurved end of theanterior sulcus. Pbstron amphisternous.
labrum slightly emarginate. sternal plates
nearly symmetrical. equal in size andPtriprcct longitudinally oval,
shape.
high up on the posterior truncated surface. Tubucks small. perforate, crtnulate, scrobiculate. rather wid€'ly scattered;tubercles smaller. more closely spaced on
both sides of the anterior sulcus and at
the ambitus; interporiferous zones of thepaired ambulacra dotted with tubercles;
plastron con.'red with close-set tubercles;
numerous microscopic granules between
tubercles. No fasciolcs.
The largest of the specimens at handincluding those from the '{uasa area
attains about 8 ern in length.
Remarks:-The above description isbased principally upon observations ofa fairly large number of specimens fromthe Arita formation. This species wasprovisionally referred to Washitaster by
the original author. However, it wasmade clear by the writer's subsequent
investigation that fasciole is not present
although a broad. ill-defined granularband decorated with tubercles surrounds
the petals and that the pore pairs in theanterior ambulacrum exhibit arrangementof Heteraster type. Thus the present
species is undoubtedly referred to Heier·aster. Except that the apical system
may be ethmophract. its detailed structure is not unfortunately ascertained due
to ill-preservation of the apical system.
The outline of the test is ordinarily
ovate as exemplified by the specimen
illustrated in the writer's previous report(TA!\AKA and OKuBO, 1954. Pl. 7. figs.
la-c). but it shows some extent of variation. As compared with the normal
form, some individuals are provided withmore anteriorly enlarged. namely ovate·
cordate outline (Pl. 16. figs. :Ia. b). whilesome others exhibit more elongated out-

4 CJ4.

Crdaceous echinoids

line as illustrated by NISIY A:'.!A (1950.
figs. 4-7). There are furthermore recognized considerable variation in the modeof alternation of the pore pairs in theanterior ambulacrum. In the outer row
of the pore pairs several longer pores
alternate with one shorter pore. The
number of the longer pores varies fromplace to pb.ce in one specimen and isalso dissimilar between individuals. being
most commonly two to five except in theproximal and distal parts. The numberof the shorter pore alternating with thelonger pore:; is usually one, but with
only one exception two.
The present species is clearly distinguished from the two Japanese contemporary species, 1/eteraster nexilis NISI·Y AMA and H. yuasensis (TAN AKA andOKUBO) by the more posteriorly eccentric
position of the apical system. the longer,
deeper anterior sulcus and the features-of pore pairs in the anterior ambulacrum.
In addition, there are some other differences mentioned below. The outline ofthe periproct is longitudinally oval in//.
macroholcus. while transversely oval in
H. nexilis. In H. yuasensis the depressed
anterior paired ambulacra are more
petaloid, the posterior ambulacra are
more pctaloid. less flexuous and morenarrowly divergent and the peristome isless deeply sunken than in H. macroholcus. The species here described isfairly close to H. oblongus (BIWNGNIART)
from the Barremian of France and theAptian of the Circum-:\lediterranean region in general features of the test. But it
differs from the latter in that the apicalsystem is far backward. the peristome
is transversely oval in outline and the
periproct is longitudinally oval.
fl.
macroholcus is furthermore distinguishedfrom the two foreign Neocomian species,
H. couloni (AGASSIZ) and H. cesarensis·COOKE by the position of the apic::ll

system, the outline of the peristome, etc.
It should be noticed that the species
here described exhibits nearly symmetrical disposition of the sternal plates,
which is regarded as being a much advanced character in the evolution ofplastron in toxasterids by DEVRIES (1960),
like the contemporary H. yuasensis described below, although it is an earlier
representative of the genus Heteraster.
Occurrence :-Loc. 6, Ishido formation.
siltstone, Neocomian (some specimens deposited in the Institute of Geology andr-.Iineralogy, Tol<yo University of Education. coil. by Y. YABE).
1/eteraster cL nexilis NISIYAMA
Pl. 16. fig. 5Compared with:1950. 1/eteraster nexilis NI:;IYA:\IA. Short
Papers JGPS. No. 1, p. 42. text-figs.
1-3.
195-l. Enallaster cf. ne:r:ilis, TAl'AK.-\ andOJ<t'no. jour. Ceo/. Soc. japan. Vol. 60.
No. 705, p. 224, pl. 7. lig. 7. text-fig. 7.

Remarks :-The two specimens at handarc fairly similar to Heteraster nexilis~ISIYAMA in general features of the test.
although they are deformed and fragmentary. Jvloreover, paying special attention to the shape and arrangement ofpore pairs in the anLerior ambulacrum,
one may can refer these specimens to
H. nexilis. A peculiar feature of porepairs is observed in one of the specimens(GSj. 6105): two long pairs alternatewith a short pair four times in the anterior poriferous zone of the left anterolateral ambulacrum. Such an abnormality
in the arrangement of pore pairs in theanterior paired petals is known also incertain foreign species. As a result of
the writer's subsequent observation of
the two specimens from the Arita for-

KeisaJcu. T.4:VAKA.
malion (GS]. 6006, 6032) which are identical with 1/eteraster nexilis by thewriter's reexamination, it is made clearthat in H. nexilis the apical system is
ethmophract and the posterior genital
plates are in contact, thus not separated
by the madreporite (Text-fig. 5). The

Fig. 5. /letl!raster nexilis NISIY A~lA.
Apical system. x 10. (GSJ. 6006. Ari ta
formation).

above-mentioned structure of the apicalsystem is observable also in one of thespecimens from the Sanchu graben (GS].
6127). It is furthermore noted that in
Heterasler nexilis the pore pairs of theanterior ambulacrum line up in four
files, thus showing the disposition of
Enal/asler type. The larger of thespecimens at hand is a little more than
'1 em in length.
Occurrence :-Loc. 2. lshido formation,
sandy siltstone. Neocomian (GSJ. 6127.
coli. by M. AlBA); loc. 7. lshido formation, siltstone. Neocomian (GSJ. 6105.
coli. by Y. YARE).

Heleraster yuasensis (TA!'\AKA
and OKUBO)
Pl. 16. figs. 6a-c. 7: Text-figs. 6a-d
1954. Enallasteryuasensis. TANAKA andjour. Geol. Soc. japan. Vol. 60,
No. 705. p. 223, pl. 7, fig. 6, text-fig. 7.

Ol<Ul!o,Type SjHJcimens :-This species wasestablished on several syntypes. The
lectotype, here designated. is GSJ. 6007.

from loc. 1. Arita formation. Wakayama.
Prefecture (TAI\'AKA ancl OKuBo. 1954,.
pl. 7. fig. 6).
Description :-Test medium-sized, nearly circular. slightly cordiform, nearly as
wide as long. rather low. widest somewhat in front of the center. not greatly
contracted behind ; adapical surface rather
ftat·topped, highest at the apical system,
sloping gently in front. truncated behind;adoral surface nearly ftattish.
Apicalsystem behind the center, with four
genital pores. ethmophract. Anteriorsulcus rather shallow, distinct throughabout two-thirds the way to the margin,
becoming much shallower, indistinct to·ward the anterior margin, thus the anterior notch. if any, very indistinct.
Anterior ambulacrum lodged in theshallow anterior sulcus. slighlly wider
than the paired ambulacra, subpetaloid;
petaloid part about two·thirds the way
to the anterior margin, poriferous zones
somewhat narrower than the interporiferous zones. Ncar the middle part apair of elongated oval. closely spaced
pores alternates regularly with a pair oflong slit-like, widely spaced pores, thus
pore pairs lining up in four files: outerpore longer than inner in each pair.
Near the proximal and distal parts longpair decreases in number, thus a longpair alternating with several short pairs.
Anterior paired ambulacra longer, slightly wider than the posterior paired ambulacra, flexuous. slightly sunken, subpetaloid: petaloid part about two·thirds
the way to the margin; porifcrous zones
much unequal. anterior zones much narrower than the posterior zones. nearly
half the width of the latter. Pores elongated oval. opposite. close together in
the anterior zones, while in the posteriorzones slit-like, opposite. widely set, theouter pores longer than the inner. lnterporiferous zones somewhat narrower than

494.

1:n

Cretaceous echinoids--,

the posterior end.

Measurements (in mm.) :-~-GSJ. 6108
LengthWidth
HeightFigs. 6a-d. Heteraster yuasensis (TAand OKUBO). 6a. Anterior ambulacrum, x 12. 6b. Right anterior paired
ambulacra. x9. 6c. Right posterior paired
ambulacra. x9 (GS]. 6108). 6d. Plastron.
x0.9. (GSJ. 6007, Arita formation).
XAKA

the posterior poriferous zones, dottedwith tubercles. Posterior paired ambulacra shorter, less flexuous than the anterior ambulacra, very slightly sunken
or nearly flush, subpetaloid ; petaloid
part halfway, somewhat narrower thanthat in the anterior paired ambulacra.
somewhat closed at the end; anterior
poriferous zones narrower than the posterior; pores slit-like. opposite. widelyset, slightly longer in the outer row thanin the inner row; interporiferous zones
somewhat narrower than the poriferous,
dotted with tubercles.
Peristome transversely oval. situatedat about one fourth the length from thefrontal margin, shallowly sunken. Plastron amphisternous; labrum slightly
emarginate; sternal plates nearly symmetrical, equal in size and shape. Periproct longitudinally oval, well up on theposterior truncated surface. Tubercles
small, perforate, more closely spaced on
both sides of the anterior sulcus and on
the plastron than elsewhere; tubercles
on the plastron slightly larger, arranged
in a concentric form with the center at

No fascioles.

23.0
23.6
8.8

The largest of all the specimens at
hand including those from the Yuasa
area attains a little more than 4 em inlength.
Remarks:-The description of thisspecies is based on observations of thespecimens from the Yuasa area in addition to those from the Sanchu graben.
The present species is clearly distinguished from the contemporary Heleraster
nexilis NISIY AMA in many respects. In
the latter the anterior sulcus is rather
deep, the anterior notch is distinct, thepaired ambulacra are superficial and lhe
periproct is transversely oval. Heterasler
yuasensis has more petaloid paired ambulacra and less flexuous. more closed
posterior paired ambulacra than H.
nexilis. The distinction is moreover recognized in the features of pore pairs inall the ambulacra. 1!. yuasensis is also
different from the contemporary H.
macroholcus and the comparisons withthat species are as described above.
This species resembles Heteraster obliquatus (CLARK) from the Albian ofTexas in the slightly depressed paired
ambulacra and the mode of alternationof pore pairs in the anterior ambubcrum.
But it differs from that species in having
a very indistinct anterior notch and alongitudinally oval periproct. Further,H. yuasensis is distinguished from H.
obliqualus by the shape of pore pairs inall the ambulacra. The species here described is similar also to H. _tiflolll·Keisak1~ TA:V.4KA

138(DESOR) from the Aptian of Switzerland
and England in the slightly depressedpaired ambulacra and the shape of porepairs in the anterior ambulacrum. However, there are distinct differences withregard to the shape of pore pairs in thepaired ambulacra between the two species. Furthermore, Heteras/er yuasensis
is easily distinguished from the foreign
Neocomian species, H. couloni (AGASSIZ),
H. oblongus (BIWNGNIART) and H. cesarensis CooKE, the second of which occurs-also in the Aptian, by its general features of the test.
It draws one's attention that the species here described shows almost symmetrical disposition of the sternal plates.
which is regarded as being a much advanced character in the evolution ofplastron in toxasterids by DEVRIES (1960),
although it is an earlier representativeof the genus Heteraster.
Occurrence :-Loc. 2, Ishida formation,
sandy siltstone, Neocomian (GSJ. 6108,·coli. by K. TANAKA, GSJ. 6123, coli. by
M. HoRIGUCHI; loc. 3, Ishida formation,
sandy siltstone, Neocomian (some specimens deposited in the Department ofEarth Science, Saitama University, coli.
by K. WAN113UCI11).
Genus W ashitaster LAJ'v!BERT, 1927
lVashitaster (?) sp.
Pl. 16. figs. 8, 9: Text-figs. 7a-c

Description:- The two specimens at
hand are considerably deformed or fragmentary. It. however. seems very likelythat the horizontal outline of the test islonger than wide, the apical system issituated far backward and the anteriorsulcus is long and deep.
Anterior ambulacrum lodged in theanterior sulcus, long, wide; poriferous

zones broader than half the width of
the interporiferous zones. Pores slit-likein the outer row. while round to ovalin the inner; pores of each pair opposite,rather close together. Paired ambulacravery unequal, flexuous, open distally.
Anterior paired ambulacra very long,considerably narrow almost throughout
the way, but rapidly widening near theambitus, very slightly sunken or nearlyftush, diverging at a smaller angle thanthe posterior paired ambulacra then turnforwards and laterally, becoming almost
straight, and then diverge laterally andcross the ambitus far anteriorly. An·
terior poriferous zones very narrow;pores minute. round, near together. Posterior zones much wider than the anterior zones; pores oval in the inner

~~--~

~lc

Figs. 7a-c. Washilaster (?) sp. 7a,Anterior ambulacrum. x 10.
7b. Right
anterior paired ambulacra. x 10. 7c. Right
posterior paired ambulacra, x 10. (GSJ.
6116).

row, while elongated oval in the outerrow; pores of each pair opposite, rather
widely set. Interporiferous zones nearly
equal to the poriferous zones in width
near the midway between the apicalsystem and the ambitus. Posterior paired ambulacra shortest, wide, flush, diverging at a very large angle and thenconverge laterally. Anterior poriferous
zones much narrower than the posterior494.

Cretar:eons cchinoids

zones, composed of minute round poresclosely spaced. Posterior poriferous zones
composed of oval inner pores and slitlike outer ones; pores of each pair opposite, rather widely set. lnterporiferous
zones w·ider than the posterior pori ferous
zones.
Peristome very eccentric in front, poorly preserved; periproct not preserved.
Tubercles small, of varing sizes. perforate. crenulate; the largest scatteredin the anterior interambulacral areas,
widely scrobiculate; interporiferous zones
in the paired ambulacra dotted withtubercles: numerous microscopic granules
between tubercles. Comparatively welldefined narrow peripetalous fasciole (orbetter to say pseudo- fasciole) observable,
crossing the anterior paired ambulacraat about one-fourth Lhe way from theambitus.
Length attains about 5.8 em.
Remarks :-Although structure of theapical system and outline of the peristome can not be ascertained due to illpreservation of the test, the presence ofperi petalous fasciole and many otherpeculiar features mentioned above may
remined us of JVashitaster. However, inthe specimens at hand the pores in theanterior ambulacrum are oval in the
inner row, while slit-like in the outerrow, the pores of each pair are notseparated by a granule and the peripetalous fasciole is not multiple but
single. These features prevent us fromidentification of the present form with
Washitaster. On the other hand, differing from Heteraster the pores in theanterior ambulacrum are aligned ineach of the outer and inner rows as in
Washitaster. There are. however. recognized abnormal disposition of theouter pores in the anterior ambulacrum
in one of the specimens (GSj. 6116).
That is. in each of the two poriferous

139

zones where pores are count about 40
pairs in the preserved middle and proximal parts respectively, the inner poresaligned, while among the outer pores
only one shorter pore is placed somewhat
inward or quite inward beyond theothers, thus the pores therein lining up
in three files as in Heteraster. Such arrangement of pores in the anterior ambulacrum is in this case regarded as
being quite anomalous and exceptional
for this individual. To sum up, the present form is here provisionally referred
to Washitaster on the general featuresof the test, although it is better to establish a new separated genus for theform when more specimens are obtained.
This form closely resembles Washitaster japonicus TA:\AKA and OKUBO
from the Albian Yatsushiro formationin middle Kyushu in general features of
the test, but is distinguished from thatspecies especially by the course of theperipetalous fasciole. In the former the
peripetalous fasciole crosses the anterior
paired ambulacra much less distally thanin the latter. The present form is tosome extent similar to the two Albian
species of Texas, Washitaster longisulcus':ADKINS and WINTON) and ll". riot:istae(ADKINS). But it is distinguished fromW. longisulcus by the much larger sizeof the test, the larger number of porepairs in the ambulacra and the greater
dissimilarity in shape of pore pairs in
the anterior ambulacrum. Comparison
with W. riovistae are given belo\v. ln
the specimens here described the peripetalous fasciole is not multiple but
single, and the pores of each pair in theanterior ambulacrum are very unequalin shape and are not separated by agranule. Furthermore. it attracts one's
attention that the anterior paired ambulacra are considerably narrow in thepresent form as well as in 1-F. japonicus

KeisaJw TANAKA

140

and TV. longisulcus.
Occurrence :-Loc. I. Ishido formation.
sandy siltstone, Neocomian la specimen
deposited in the Chichibu National Sci·
ence Museum, coli. by K. T AKEI) ; loc. 7.
Ishido formation. siltstone, Neocomian(GS]. 6116, 6117, coli. by K. TAN AKA
and Y. YABE).
References
ADKI:-;s, W.S. (1928): Handbook of the
Texas Cretaceous fossils. Texas Unill.
Bull., no. 2838, 385 p., 37 pis.
- - and Wr1'TON. W. M. (1920): Palaeontological correlation of the Fredericksburg
and Washita formation in 1\orth Texas.
Ibid., no. 1945, 84 p., 21 pis.
ARAI, F .. TAKE!, K., I!OSOYA, s .. IIAYASHI,
S. and TAKAHASHI. K. (1958) : Descriptions and some considerations concerning ripple marks discovered in the Sanchu graben. Chikyulwgaku, no. 40. p. 112 (in japanese with English abstract).
CLARK, \V. B. (1893): The Mesozoic Echinodermata of the United States. Bull.
U.S. Ceo/. Surv.. no. 97. 207 p., 50 pis.

CooKE, C. W. (1955): Some Cretaceous echinoids from Americas. U.S. Ceo/. Surv.,
Proj. Paper, 264-E. p. 87-l12. pis. 18-29.
text-figs. 1-1.
CorrEAU, G. II., PEROK. A. and GAUTHIER.
V. (1876-188-l):
Echinides fossiles de!'Algerie: Description des especes recueillies dans ce pays et considerations
sur leur position stratigraphique. ;1nn.
Soc. Ceo/. vol. 4. no. 6, p. 1-30, pis. l-2;
ibid., vol. 6, no. 4, p. 1-91, pis. l-8.
Df:NrzoT. G. (1934): Description des Massif
de Marseilleverge et de Puget.
Ann.
Mus. d'hist. nat. Marseille, mern. 5, vol.
26. p. 140-1·12, pl. 5.
Di,SOR, E. (1855-58): Synopsis des echinides
fossiles. 490 p., 44 pis.
DEVRIES. A. (1955) : Etudes sur Toxastert•i/lei (GAUTIIIER sp.). Pub/. Serv. Carte
Ceo/. Algerie (nouv. serie), bull .. no. 5, p.
127-155, pis. 1-2.
- - (1955) : Note sur le genre Helerasler.
Bull. Soc. Ceo/. France, 6 ser., vol. 5, p.
315-323. text-figs. 1-2.
- - (1960): Contribution a !'etude de quelques groupes d'echinides fossiles !•Algerie.
Pub/. Serv. Carte Ceo/. Algerie (nouv.
serie). mem., no. 3. p. 1-278. pis. 1-39.

Explanation of Plate 15
Figs. la-c. Pygurus (Pygurus) complanafus n. sp.
1a. 1\dapical side, x2. lb. Adoral side, x2. lc. Left lateral side. x2. Presumed Ishidaformation. (Holotype. GSJ. 6090).
Figs. 2a-c. Pygurus (l'ygurus) comp/analus n. sp.
2a, Adapical side, x2. 2b. Adoral side, x2. 2c. Left lateral side. x2. Presumed Ishido
formation. (Paratype. GSJ. 6091).
Figs. 3a-d. f'seudholastrr n. sp. ( ?)3a, Adapical side. x 1.5. 3b. Adoral side. x 1.5. 3c. Left lateral side. x 1.5. 3d, Anterior
side. x 1.5. Ishido formation. (GS,J. 60,16).
Figs. 4a-c. Pseudholaster n. sp. ( ?)4a, Adapical side, x 1.5. 4b. Adoral side. x 1.5. k, Posterior side. x 1.5. Ishida formation. (GSJ. 6050).
Figs. 5a. b. Toxaster sanchuensis n. sp.
5a, 1\dapical side. x 1.2. 5b, Adoral side. x 1.2. Ishido formation. (Holotype, GSJ. 612,1).
Figs. 6a, b. Toxasler sancfwensis n. sp.
6a, Adapical side, x 1.2. 6b. Adoral side, x 1.2. Ishido formation. (Paratype. GSJ. 6110).
All specimens here illustrated are internal moulds.

TANA.KA. : Cretaceous echinoids

Plate 15

494.

Ct·eta.ceous ech:inoids

DuNcA:x. P.M. (1889): A revision of thegenera and great groups of the EchiJJOidea. }our. Linn. Soc. London. Zoology,
vol. 23, 311 p.
KIER, P.M. (1962): Re\·ision of the Cas.
siduloid echinoids. Smithsmt. Misc. Col/.,
vol. 1H. no. 3. publ. 4500. ?62 p .. 4-t pls ..
184 text-figs.
LA~tBERT, J. (1926): Considerations sur lesechinides de Ia Commanche serie duTexas. Br1ll. Soc. Ceo/. France. 4 ser ..
vol. 26. p. 263-278. text-figs. 1-2.
- - (1931) : Etudes sur echinides fossiles
du ~ord de !'Afrique. AUm. Soc. Ceo/.
France. N. S., vol. 7. no. 16. p. 1-228. pis.
1-8.
--and TII!EI~Y. P. (1924): Essai de nomenclature raisonnee des cchinides. fasc. 6-9,
p. 385-607, pis. 10-15.
Lm~IOL, P. de (1873): Echinologie helvetique: Description des Oursins fossiles deIa Suisse. Part 2, Echinides de Ia periode
cretace. Mater. Pal. Suisse. 6 ser., p. 1398. pis. 1-33.
MoRTE~SI·:N. Th. (1948):
A monograph of
the Echinoidea. IV-1. llolectypoida. Cas.
siduloida.
- - (1950): A monograph of the Echinoidea.
V, Spatang11ida.
N1s1Y A~IA, S. (1950) : Two new species of
the Toxasteridae from japan. Shm·t
Papers, Inst. Ceo/. Pal. Tohoku Univ .. no.
1. p. 42-47, figs. 1-6.
ORBIG:-.Y. A. d' (1853-56): Pali:ontologie
fran~aise: Description des animaux in.

A ritarntrChichibu-gun~ 5(1!1\
I-Iikage
8~
Ilonya~Minamimaki-cho Iff~ !!If
Minamisaku-gun iYHt.:?..llh
Myoke
I!JJ
Nakazato.mura'-fl ![ .f.f
Ogano-chotJ-1/'[!l!fiOJ

*

*

141

vertebres. Terrain cretace: Echinides.
Yo I. 6 ( 1853-60), p. 1-595. pis. 801-1006.
SztiRE"lYI, E. (1955): Echinides cretaces de
Ia Bakony. Geo/. Hung .. Ser. Palaeont ..
fasc. 27. p. 1-332. pis. 1-22. text-figs. 1-45.
TAKEI. K. (1963) : Stratigraphy and geologi·
cal structure of the Cretaceous Systemin the eastern part of the Sanchu graben,
Kwanto mountainland. foul'. Ceo/. Soc.
japan. vol. 69, no. 810. p. 130-146 (injapanese with English abstract).
TA:XAKA. K. and OKL'BO, M. (1954): On
some echinoids from the Paleocretaceousof the Yuasa district in the Kii Peninsula and the Yatsushiro district in Kyu.
shu. Ibid., vol. 60, no. 705. p. 215-227,
pl. 7. text-figs. 1-7.
- - and SHIBATA. M. (1961): A new speciesof Aphelaster from the Lower Cretaceou;,of japan. Tra11s. Proc. Palaeont. Soc.
japan. N. S .. no. 42. p. 68-72. pl. 10. text·
figs. 1-2.
ToKUNAGA, S. (1903) : On Lhe fossil echi·noids of japan. jour. Col/. Sci. Imp.
Uniu. Tokyo, vol. 17, art. 12, p. 1-27. pis.
1-4.

WRIGHT. T. (1864-82): Monograph of the
British fossil Echinodermata from theCretaceous formations.
/'a/aeon/. Soc.
London, 371 p., 80 pis.
YABE. Y .. KAl"EKO, S. and AKAGI, S. (1955):
On the Lower Cretaceous deposits in thenortheastern border of the Sanchu graben.
jour. Ceo/. Soc. japan, vol. 61. no. 721. p.
503-505 (in Japanese).

Onozawa
Saku-choSanyamaSebayashi
Shigaraki-gun
ShiroiTano-gunUeno.muraYuasa* !llf9.. lllfiR.
(1,:

~

lfli

Ill
.f+;

11' ~ l!Y.
r'ttl'
~ !llf Uti
1.: !!lf H

l'Ll

t~

142

Keisaku TANAKA-------

Explan::tion of Plate 16
Figs. la-c. Toxasler sanchuensis n. sp.
Ia, Ada pica I side, x 1.5. l b, Adoral side. x 1.5. lc. Left lateral side. x 1.5. Ishido formation. (Paratype, GSJ. 6042).
Figs. 2a-c. Toxas/er sanchuensis n. sp.
2a, Ad apical side. x 1.5. 2b, Adorsal side, x 1.5. 2c, Left lateral side, x 1.5. Ishido formation. (Paratype, GSJ. {i041).
Fig. 3. 1/eleras/er macroholws (NtstYAMA)
Adapical side. x 1. lshido formation.
Figs. -la, b. Heleraster macroholcus (:\'ISIYAl.IA)
4a, Adapical side. xI. 41.>. Adoral side. xl. Arita formation.
Fig. 5. Heleraster cf. nexilis NtsiYA~IA
Adapical side, x 1.5. Ishido formation. (GS]. 6105).
Figs. 6a-c. Heterasler yuasensis (T Al\AKA and OKUBO)
G:~. Adapical side. x 1.5. 6b. Adoral side, x 1.5. 6c. Right lateral side, x 1.5. Ishido formation. (GSJ. 6108).
Fig. 7. Heleraster yuasensis (TA=":\KA and 0Kuno)
Adapical side, xl.5. Ishido formation. (GSJ. 6123).
Fig. 8. I.Vashitaster (?) sp.
Ada pica] side, x 1.2. Ishido formation. (GSJ. 6116).
Fig. 9. IVashitaster ( ?) sp.
Adapical side, x 1.5. Ishido formation. (GSJ. 6117).
All specimens here illustrated are internal moulds.

TAN AKA :Cretaceous echinoids

Plate 16

14:3
PROCEEDINGS OF THE PALAEONTOLOGICAL SOCIETY
OF JAPAN

El;f;i51=.!ft.r~~?g 9o rm~J~.i>J:.a r~t!li.lilrJJ~~) !1:-::>~'"'l...................... ;kJi¥.

~

c:fl·l.·c l..d.:JT1:.ttf&~O)i5.1tlJJ!l!c ti1:.!1mO)~i'lH:£
c l"Ci5kti'lful!¥~<fr.t:·IC)J IC"?P"L 0),.., :/:f.:/ '7
Ali 1965 1F 6 Jj 20 B ( B ) ~IR;k~Jl!l *ml.ltl!~"t­

A new species of a whale tympanic tone
from Taiwan, China (ftf.?'E) ........... .
.......................... Tunyow HuA:-<G-*!<::~nr::toP<::I~fH!li~ttt..: (~1m~ 22 ~L

1.\wi'Dif<illl!O)~tJt;fl;c ~ O)~M1F1t.Planktonic Foraminifera from Oga Peninsula. Akita Prefecture (f\';Mc) ........ .
.. Yokichi TAKAYANAGI & Tadamichi 0BA
Asanonella shozii, n. gen., n. sp., (Family
Discorbidae) from Tokunoshima, Kagoshima Prefecture, japan (it~1C) ....... .
.......................... Tun yow HUAJ'\G
Carboniferous conodonts from the Atetsu
Limestone .. Toshio KorKE & Hisayoshi !Go·On the Daone/la and llalobia bearing facies
in the Malayan Peninsula ............. .
. . Teiichi KoBAYASIII & Akira Tor..:uvA:>.IA·On a Lower Cretaceous pelecypod, ·• Cyrena
naumanni ", from Japan ............... .
.............. ltaru HAY AMI & !sao NAKAI
i/t.::fO) Pterotrigonia 11:-::>~ 'L ........ llfiiB!!Y~?'jff/:XmO)<frJTIY:1JJM0 .f.lftEllf.m(t;iij s i!VJ:tl-rr......... .

. . . . . . . . . . . . . . . . . . . . . . . . jjj;t-J:!m=. • ;;f:~J.I)~
A Mesozoic Ammonite from the Island of
Curacao, West Indies (ft~O ....... · · · · ·...... Tatsuro MATSU~IOTO & D. J. BEETS
3RjljitlJ.ItlJi!fi.::~ v:. 7 ........ !J-g§{ij!=. • ;kt-J'a.JHt
Two Fo~;si 1 Species of Discinisca (Brachio·poda) from North Honshu (ftMc) ...
........ Kotora HATAI & Shozo HAYASAKA
Planktonic Foraminifera from the Somachi
Formation, Kikai-jima. Kogoshima Prefecture (ft~) ............ Tunyow HUANG
S/ './:f.:/ t7 A

I Jt!li.ltl!:f-J~<j:r.[> c l f:_ ~1=_f\';i&$0)i5.1tlJll!lc~~~O)~~<j:r .(..!1:) J~tMiJi!rJJ~~==-~•1!
rf!~llM1tEEE~$.o<±ct--r~~!lmllf.~............... *e~~:7c.................. TfjJII i!lt~-f*ftE 11: J:. ~a~ffO) t£i! .......... t~.fitf~r-li'ii\Lll~.f1!!0)mJl!lE1\Ei~i!H$: · · · · · · · · · · · .J!i#BB=.

News
<)

?f! 2 [ill['!<i~:ffi~"f'0~ (2nd International Conference on Palynology) li 1966 ¥8 Jj 29 B J:.
IJ 9 Jj 3 13 i"Z: ::t 7 './ JfO) Utrecht "Z?!m1!fi~tLll'f71-A«i\J:tO)ft!!, ~O);j;jiiufi~7'Jiftit.:;tt~"j·}E"Z?j).Oo
Palaeophytic: Mesophytic; Upper Cretaceous and Tertiary: Pollen and Spore Morphology
and Pollen Dispersal; Palynomixtum.
l!!~$t:lilXO)Jffi 1) 0<)

Secretariat Working Committee. 2nd International Conference on Palynology.
cfo Royal Netherlands Industries Fair. Vredenburg, Utrecht, Netherland
i:i!J~r!"i1=.~~)l!!-8' (International Palaeontological Union) 0)~-3-li 1964 ~ 12 Jj 16 13-21 8 iC-1''./ f-'0)~ ~ -7•J --z:IU~iJ.n"f:ie!0$ll'i7'J::>iMtt-nL1) ~ :!Jl:: M.R. Sahni (-1' './ r)
aiU0~:

13. Boucek ( 'T"' 7 :::1 7. t1 ... '""-\") ; C. L. Arambourg ( 7 7 './ 7.) ; K. M. Sultanov( '/ )!!!)~$:

B.S. Tewari (-1' './ r)~ ~·: A. L. McAlester (7 ;J 'J :h-2':!'/t~)
tflfj~Jil. 9 ~0)? '!::> R;f;J:.IJ li, t~;f;~f$ · 'J;;ff;_R-iitiitl'iJ~~:bu l n'oc

144
2)

tll:WJ/HI<I~ 5 f:fllX!R!C]}Ift.:o

1 -a-t=~.,_,, (?71vic)
2 7 ;;73 7 ;1 1) ;tJ (ffi;ft)
4 7 7 1) ;tJ
5 .:t -1:7"" 7

1'2!.t M. Lecompte (77:/7.:): 1,it-"$ R. Coni! (77:/'A)
CF.I*): ~$ il%JH-::: (D;t:)Wells (-8-*~) : ;;tt-$ A. R. Palmar ((t~!Jil)~ft: H. Hollard ( 'E: a ._, :::1) : (¢$ lVI. S. Willefert ( -r o .7 :::1)
1.';=;{i; C. A. Fleming (:=.,-;; -7 :/ r) : (it$ G. I{. Stevens.
~N: ·H*~--~ft: ]. W.

(-"'~-:/-7:/!-')

3)~O)t'Jl~ (JftJ':J:.;?~t;') )J.:::J'j,~_l;l_1',;~~lLld:o

I Palaeontologia Universalis ;_;j'l,K R. Dehm ( !-' -f 'Y)
2 Directory of the Palaeontologists of the World ~f!ft: L. G. Love ( 1 ilf 1) .;;~.)
2 Palaeoecology ~~ft N.D. Newell (g.*ft;j)
Sub·Committee-Reef Building Organisms
4 Palaeobiogeography ~J':l.R C. J. Stubblefield ( 1 ilf 1) .;;~.) ;_;ft<jl(;:: llI) !l!!fh!f:tttJt*,t~1JUVt'P~,

Sub.Committee-Migralion

5 Evolution ;_;ft_R 0. H. Schindewolf ( ~-1 ·:1)~' Z>o4)@~f!<j:>!C B*.t I)H}!~IIP~j;:;R;¥~/Jil L "L

Sub-Committee-Biometrics: Sexual dimorphism in fossils: Ontogeny an~
phylogeny.
llil~~{i!i~lo®J~:i!J!&,(;J:I'mll!'i!Jt!!~i!l!tr JJ.;:Jf!;l~!:t¥JJ"ri!l!-8'0 filli/iiC::)JUHQ.-t ~ f.l!fl{ () c!: tJ. -?t::.o

B*~i=f.f.j~,i~:k.lfi'(;~f:i.J!i!Vf~i!l!~~n~J: l) r:;Jl!CDill! IJ .lffi~:bl<fl IJ i U.:CD<:':I'.i~l?-rt Li-t":Jg llii:!l;;l~lflj:'f.•'Hf.if<,~!C:::t.;~'"L Divisional Meetings -rolirii)(.;E-}U~ Lt:.~'A{;l, ~)( · 1/'-;/Jv'A...;.-.;;~.I f'.;(O) Abstract ~HL-c. ll~1J.'l'l;f"OJ~~~l'illr~ (Section)!C::11lJifr L~l:~-·F~~',

it::.. IJtml?:J..~. Tours. '0~N''OY;I~:;t}'E~t.; LCV~iJn:f.l~iH). ID~~tl~OJ~"l:l~l'liSI"]!c11lJif! L}~.i1j.'f<5P.,

P"f1.t{>Af,(!CIIU IJ fJl<fl lJ i ]-OJ"C, .:C CV!fX~tit'lRli~;t}Hfllf'~IC-If; L "L j) IJ i "JJ·,,
fJ: ;j'j, i!i'!.(:.!ff!J"f:ml f~O) ~i~illlP'J (Section) (i)ifJJ6J\:;!i!tOit/llS;;!;:ll~f~.ll2\}''l!f!jjf:;k"f".Jl!!"f:li'lllt!!'rl't'-3':1,.{~m11 Ji•I::k Jl1'f"f'{f.T-1~J~. ~ 4 S~St"Jlt!!rr~r~r~~m~=t?J'.i-f" ~n!t ilftilllitYJ
1"Ci:J~o

ffi.i
iJ!.i
.li.
@ ~HEHH~ · Jl'lii$R~O)filli;fi:t 7 B tft'EI.I.t !J *~ 1 7' F.1 r::t)f:.IJ ...- 71 $!i1.JO).lik~ · i1 i1J11J•1:~1f..;E-:ff
fJ:P 8 B 1!1'1ilffltlii!Lt.:.
@) 4l;~fjifi~9HJI;!:'i!i~~~JVf~O)f.:;Jb7' ;/ ...-- ~ · .:t 7 :Y 1/' "'-JcJit 9 rJ J: 1lJilJ;£ Lt:.o@ 4l;ft~JIL.'.;!(tll!it/it~!h1Vf~0t.:~ 9 JH 1u*l~h(c]lttfl~ Lt.:.

1!

@)~H~*~J-;1J0)~~1:tJ: t?atr~Hiii'f:05t'fl:::i'ilt 7.>it!!f:f~I'0M6;}J l::)f L E1-*+1!~1'~Jt1J<~lj.
~tJ.f.:oshall call a Special ~Ieeting at the wriLLen request of more than one-third of
the members. The request shall be granted only if the written statement fully
explains the reasons for assemhly and items for discussion.
Article 19. Members unable to attend the General ~Ieeting may give an attending member
a wrinen statement signed by himself tru!Hing the bearer with the decisionof business matters. Only one attending member may represent one absentee.
Article 20. The decison of the General Meeting shall be by majority vote. When thenumber of votes is equal. the President shall cast the deciding vote.
Article 21. The President and Councillors shall compose the Council. The dicision of theGeneral Meeting concerning administration shall be considered and implemented
by the Council.
Article 22. The Executive Council shall carry out the decisions of the Council.
Article 23. The fiscal year of the Society shall begin on the first of January each year andend on the thirtylirst of December of the same year.
Arlicle 24. The amendments to the Constitution of the Society shall be decided at theGeneral M(~eting and must he approved by more than two-thirds of those members who arc in attendance.
Addendum l) Voting in the Council shall be by unsigned ballot.

_j

1m 00 Jtt!

-

1m

rut

~iJll:$.i.Hii!WB

f:l
---·

m 92 1m f~J --~
~-

'f· ~

-)..:_~"j:

1966tf~~ . ~·~:;

~I:

').;,

q: 1966 ~ 1 fJ 2·1. 25EJ 'l~;g 92@1§11~ (-=f-~:7;:~) :*1965 {r 11 JJ G, 1 n

1965 iflOfJ 10 131965 ij! 12 Jl 20 B

11 JJ 6 El ( ±.) !ftMY;; 1' &cJ'~'!ti:~fvJi 1 i'l=!f'IJ.J • .ff!ls!!0~ :.-' ,f!;; ~? .l· (lliil6A: m;;$:: II· DfJrn!'Y
t![l). lfUii911!f30.HUIJ!IfL tr-uu.&u 1-fi~llil·W~: H:Jilli-0, lfi&i&~: Jl!m7:/7oJ·i!J~I#oitL'IftOJ.A7-1'
ri~HliJ.

11 Jj 7 n ( 1:1) fi.IIA~~iWL lf·u(I91T'.f 30 01JIJIJf.lo-0-"J: =f~;I:"[;:;:FJ!·~::i$ (jllj-f·;il~lf(~I:Ul:J!t, -i;E~Iif:r)v{1·)~'1:/[igtit: t~IC3i.~.i!l!hlvJ.::.. ~ (iJiJLLI!'Yfll)~).

1ii· r'h :~ n ~~R JtHu .~;;@@

JJ;j:·:{;(~jJ;:1J:h;)jltlUJ~::U G~ li~ · .11!!\."t·:;;: • -'iJl<iliO ·~illlli.!: VC1lii~~n+:t.t-.J.'~- ·:Hi:Jl~~!ld.:.,ij] II ~lf'f~YJ}j]):~j,fi:ci1U.Kl11:tlOJc~•!J:.(-I;:.:-.~:Jcf~0l~f:Jt~. fllil1~·:j:(j:j~JJ.lli~~hfi1r 'i:J!I!f;M~0;;$::1il~i!VJ
irr~i!lt~rf]E;:,> 1::1\9d;j.:!J!JJ~I.llt1i#0l'Vf1\!~~ ~l~7.ljj£~ l., t.: 0@

lllH11 ·11 #'f!£fl.!Vfn~H~~~ff!l!:: ~:l:. l!f;1&L10rll~0f.~*~·~~~: L <:1'3~,:·.){!+! · ~.fi-;kM · WJ*!i(l\J!ii'l· w!I!F.J'm ·li'IHU!If!fj;; · WJ#It<It ·l~Jt!Ifl!i (7-1' ?~*t~fO >t-ff!i~ld.:. i\!B~f.l~-c~Jel.,t.:;:¥;.';20JWl~~ i'H::a. c uJ<Pt' 0 tiDJHfit.:~i~iJ:~I! at: El OJlfQ?;oiJ> ~Y:J t.: o

1 9 6 5 1f. 9 J.j25~1
19651f.9J.l30EJ

a *~~:tb~~fil\f ·It?¥ilf.w msg ~4 00 F3

I

'I
I

J

:Jlt);(:;k~~~iillJt!!'l'f~~~Pi

iiij

9]

*

fl*~~:tt~~~·

rr =Ifm(~ ~ p

*

:Jt:
~

m

ft
~

m

Jt! J.l{ 8 4 7 8 0 ~)J:iJ JliU =If J.!i 'llil *"~.! .u~ 1:{ ~ z ~t: 2 1 13::f:f,l1~ 11r-r:illii1J t~:l:\': ~ tt 1:~
Ill
5t:;

r

CONSTITUTION

of the
PALAEONTOLOGICAL SOCIETY OF JAPAN
Article I. The Society shall he known as the Palaeontological Society of Japan.
Article 2. The object of the Society is to promote the study and popularization of palaeon·
to logy and relal eel sciences.
Article 3. The Society, to execute Article 2, shall undertake the following business:
1. Issue the Society journal and other publications.
2. Hold or sponsor scientific le6tures and meetings.
3. Popularize the science by field trips, scientific lectures and other projects.
4. Aid and encourage research work; award outstanding contributions tol he Society: carry out the objectives stated in Article 2.
Article 4. To attain the object of the Society, the Society may, by decision of the General
Meeting, establish within it research committees.
Article 5. The society shall be composed of members who are active or interested inpalaeontology or related sciences.
Article G. The members shall be known as Regular .l'vlembers, Fellows. Pal ron and Honorary
Members.
Article 7. Persons desiring membership in the Society are requested to fill out the necessary application forms and receive the approval of the Council.
Article 8. Fellows are persons who have held Regular Membership in the Society for morethat ten years. have contributed to the science of palaeontology. have been
nominated by five Fellows and approved b~· the Council.
Article 9. Patrons are organizations supporting Article 2 and recommended by the Council.
Article 10. Honorary Members are persons of distinguished achie\•ernent in palaeontology.
They shall be recommended by the Council and approved by the General Meeting.
Article 11. The members of the Society shall be ohliged to pay the annual dues stated in
Article 12. Members shall enjoy the privilege of receiving the Society journaland participating in the activities stated under Article 3.
Article 12. The rates for annual dues shall be decided by the General Meeting. Rates forannual dues arc: Regular Members. Yen l,OOO; Fellows. Yen 1,500; and Foreign
1\·lernbers. $ 4.00. Patrons are organizations donating more than Yen 10.000 annually;
Honorary Members are free from obligations.
Article 13. The budget of the Society ;;hall be from membership dues, donations and be·stowals.
Article H. The Society. hy decision of the Council, may expel from membership persons
who have failed to pay the annual dues or those who have di~graced the Society.
Article 15. The otlicers of the Society shall be cnmpos,,d of one President and fifteen Councillors. among whom several shall be Executive Councillors. The term of office
is two years and thev may be eligible for re-election without limitation. The
Presiden.t may appoi~t se\·eral persons who shall be Secretaries and Assistant
Secretaries. An Executive Council shall be nominated and approved by theCouncil. Councillors shall be elected from Fellows by vote of returned mailunsigned ballot.
Article Hi. The President shall br a Fellow nominated and approved by l he Council. The
President shall represent the Society and supervise the business affairs. The
President may appoint a Vice-President when he is unable to perform his duties.
Article 17. The Societ}' may have the honarary President. The honorary President shall berecommended bv the council and approved by the General Meeting. The honor·
ary President ~ay participate in the Council.
Article 18. The Societ}' shall hold regularly one General Meeting a year. The President
shall be Chairman and preside over the administrative affairs. The program
for the General Meeting shall be decided by the Council. The President may
call a special meeting when he deems il necessary. The General Meeting re·quires the attendance of more than onc·tcnlh of the members. The President