ISSN 0031- 0204

Transactions and Proceedingsof thePalaeontological Society of Japan
New Series

No.

150

Palaeontological Society of Japan
June 30. 1988

Co-Editors

Hisayoshi IGO and Tsunemasa SAITO

Editorial Board: Yoshikazu HASEGAWA, Itaru HAYAMI, Hisayoshi IGO (chief), Makoto KATO,
Itaru KOIZUMI , Yasumochi MATOBA, Kei MORI, Hiroshi NODA, Kazunari TANABE,
Tsunemasa SAITO, Kazuhiko UEMURA, Akira YAO
Officers for 1987-1988
President : Tatsuaki KIMURA
Honorary President: Teiichi KOBAYASHI
Councillors : Kiyotaka CHINZEI , Takashi HAMADA, Yoshikazu HASEGAWA , Itaru HAYAMI,
Hisayoshi IGO, Junji ITOIGAWA , Tadao KAMEl , Tatsuaki KIMURA, Tamio KOTAKA ,Kei MORI , Ikuwo OBATA, Tsunemasa SAITO, Yokichi TAKAYANAGI, Kazushige
TANABE , Toshimasa TANAIMembers of Standing Committee : Kiyotaka CHINZEI (Membership), Takashi HAMADA (Foreign Affairs), Itaru HAYAMI (Finance), Hisayoshi IGO (Co-Editor of Transactions),
Ikuwo OBATA (General Affairs), Sumio SAKAGAMI (Co-Editor of Special Paper),Kazushige TANABE (Planning), Yokichi TAKAYANAGI (Editor of "Fossils"), Juichi
YANAGIDA (Co-Editor of Special Paper)
Secretaries: Katsumi ABE (Planning), Takeshi ISHIBASHI (Special Paper), Kunihiro ISHIZAKI("Fossils"), Tomoki KASE (General Affairs and Membership), Hiroshi NODA (Editorof Transactions), Terufumi OHNO (Membership), Tatsuo On (Planning), Kazuhiko
UEMURA (General Affairs), Toshiyuki YAMAGUCHI (Finance)
Auditor : Noriyuki IKEYAThe fossil on the cover is Vicarya yokoyamai Takeyama, an Early Middle
Miocene gastropod from the Kurosedani Formation at Kakehata, Yatsuo-cho,
Nei-gun, Toyama Prefecture, central Japan (Collected by T. Kotaka and KOgasawara, IGPS No. 99075, photo by S. Ohtomo and Y. Kikuchi, xO.9).

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Trans. Proc. Palaeont. Soc. Japan, N.S., No. 150, pp. 435-452,7 Figs., June 30, 1988

856. LATE PALEOZOIC FORAMINIFERS
OF THE OGAWADANI FORMATION,
SOUTHERN KWANTO MOUNTAINS, JAP AN*
FUMIO KOBAYASHI
Yanagikubo, 2-64-1011, Higashi-Kurume 203, Tokyo

Abstract. Forty-seven species of Middle Carboniferous to Middle Permian foraminifers
are discriminated from the limestone blocks of the Ogawadani Formation, distributed in ~heSouthern Belt of the Chichibu Terrane in the Kwanto Mountains. Among them, mne
fusulinacean species belonging to five genera are described with brief geologic note of the
Ogawadani Formation.

Introduction

Ogawadani Formation proposed by Ozawa andKobayashi (l986).
Through a detailed field work in thesouthern part of Kwanto Mountains, I newly
obtained many fusulinaceans and other foraminifers from the limestone blocks contained in the
Ogawadani Formation. Total number of foraminiferal species attains to 47 referable to 32
genera. They came from 24 localities of myown collection and also of previous workers.
Nine fusulinacean species of them are describedherein. All materials described and cited arestored in Department of Geology, National
Science Museum, Tokyo.

Huzimoto (l932) established a fault-bounded
unit, the Shiromaru Paleozoic Belt, within
Jurassic formations near Shiromaru in thesouthern part of the Kwanto Mountains. Four
fusulinacean species, such as Fusulina girtyi(Dunbar and Condra), Pseudofusulina ambigua(Deprat)?, Pseudofusulina kraffti (Schellwien)
and Cancellina primigena (Hayden), were described from Unazawa, Otakezawa and Komyosan within this belt (Huzimoto, 1936). He also
introduced the Tamagawa Group for the unit
containing Jurassic Torinosu-type fossiliferous
limestones and Jurassic radiolarian cherts, which
is distributed in the west of the Shiromaru
Paleozoic Belt (Huzimoto, 1939). Subsequently,
Kobayashi (1939) found Neoschwagerina(Yabeina?) sp. from Aterazawa, north of
Okutama (Hikawa), and he doubted Huzimoto'sview of the Tamagawa Group.
Recently, Hisada (l984) listed Triticites? sp.,
Pseudoschwagerina sp., Acervoschwagerina sp.,
Pseudofusulina sp. and Schwagerina? sp. fromthe limestone blocks exposed at Kawanoridani
and Ogawadani. These blocks are included in the

Geologic setting
The Tamagawa Group is composed of four
formations, such as the Unazawa, Ogawadani,
Hikawa and Gozenyama Formations (Ozawa andKobayashi, 1986). This group is complexly
folded and faulted, but it generally strikes
northwest to southeast and steeply dips northeast.
The Ogawadani Formation, typically crops
out in the Ogawadani valley, a tributary of the
Nippara River, is discontinuously distributed
more than 14 km in length and about 2 km in* Received May 12, 1987; revised manuscript accepted
May 30, 1988.

435

Fumio KOBA YASH!

436

~1
~2
~3
r:::::::l 4
Cd' ",- 5"'...', , "

Ea
L:J 6
......

I,[Q7

Figure 1. Geological map of the Southern Belt of the Chichibu Terrane in the southern part of the
Kwanto Mountains. 1-5: Southern Belt of the Chichibu Terrane composed of the Tamagawa Group; 1:
sandstone and shale of the Unazawa Formation, 2: chert and siliceous shale of the Unazaw a Formation, 3:
Ogawadani Formation , 4 : Hikawa Formation, 5 : Gozenyama Formation, 6: Middle Belt of the Chichibu
Terrane, 7: Shimanto T errane.

the maximum width. This formation is in a fault
contact with the Unazawa Formation (Figure 1).
The Ogawadani is characterized by various sized
and shaped blocks of basaltic rocks, limestones
and cherts which are chaotically embedded
within arenaceous and sheared pelitic rocks,
Longer diameter of blocks attains more than 50
m. The age of limestones is Middle Carboniferous

to Middle Permian given by foraminifers, whereas
the age of cherts mostly indicates Late Triassic
by conodonts. These blocks are considered to be
exotic and arenaceous and pelitic rocks arematrix of the Ogawadani Formation. The pelitic
matrix is assigned to Jurassic on the basis ofradiolarians from the Ogawadani valley (Hisada,1984).

856. Paleozoic Foraminifers of Ogawadani Formation
Limestones of this formation commonlyoccur in association with basaltic rocks and/or as
small blocks within mafic hyaloc1astite. Most ofthem are lithologically micritic limestone. Someof the micritic limestones contain siliceous

437

concretions or radiolarian remains replaced bycalcite, and alternating beds of chert andmicritic limestone. Encrinal, algal, oolitic andpisolitic limestones are also recognized.
Table 1 shows the Late Paleozoic foraminifers
discriminated from the limestone blocks of the
Ogawadani Formation. Fossil localities are shownin Figure 2.

Mt. Tenmoku
A

N

MitakeAMt.Mitake

5 Km

Figure 2. Localities of the Late Paleozoic foraminifers. Shaded area shows the distribution of the
Ogawadani Formation.

Fumio KOBA YASHI

438

Table 1. Late Paleozoic foraminifers of the Ogawadani Formation. Species shown by -1, -2 and-3
are based on Hisada (1984), Huzimoto (1936) and Kobayashi (1939), respectively.

--------

Locali ty
1 2 345 6 7 B 9 10 1112131415 16 171B 1920 21222324
X X X X X
X X X
X
X
X X
X
X X
X
X
X X

Tubertinina spp.
Radiosphaera sp.
Pachyphloia ovata Lange
Palaeo textularia sp. A
P. sp.B
sp.C
P.
X
Cribrogenerina? sp.
X
X X
X
X
Palaeotextularidae gen. et sp. indet.
Tetrataxis conica Ehrenberg
X
X
sp. A
T.
sp.B
X
T.
X
spp.
X
X X
T.
X
Abadehella coniformis Okimura& Ishii
X
Globivalvulina spp.
X
X
X
X
X X X
X
X X
X
X
X
Endothyra spp.
Kahlerina sp.
X
Bradyina? sp.
XPamirina? sp.
X~
Rauserella sp.
X
Beedeina higoensis(Kanmer a)
X X
X
Fusulinella sp.
X
Fusulinidae gen. et sp. indet.
X
X
Schubert ella sp.
X
X
Neofusul inella sp.
?
Yangchienia compressa(Ozawa)
X
Dunbarula schubertellaeformis Sheng
X X
sp.A
D.
X
sp. B
X
D.
Acervoschwagerina sp. -1
X
Chusenella spp.
X
X
X
'Parafusulina"gigantea(Deprat)XP.
hirayuensis Igo
X
P.? sp.
X
X
Pseudofusulina kraffti(Schellwien) - 2
X
P. spp,X
X
X
X
X
X
Pseudoschwagerina sp. -1
X
Tri ticites? sp.
X
X
Schwagerinidae gen.et sp. indet.
X
X
Verbeekina verbeeki(Gein itz)
X
X
V.
sp.
X
Pseudodol iolina pseudolepida(Depr at)
X
X
X
X
Neoschwagerina craticulifera(Schwager)
X
X X
N. haydeni Dutkevich& KhabakovXsimp/ex Ozawa
N.
sp. A
X
N.
spp.
X
X
X
N.
X
Yabeina g/obosa (Yabe) -3
XX
X X
Agathammina spp,
X
Baisalina sp. cf. B.9lOboSawanr
Hemigordius? sp.
X
X
Fisherinidae gen, et sp. indeq

I856. Paleozoic Foraminifers of Ogawadani Formation
Systematic description
Family Fusulinidae von Moller, 1878
Genus Beedeina Galloway, 1933 emend. Ishii,
1958

Beedeina higoensis (Kanmera)
Figures 4-7-17
Fusulina higoensis Kanmera, 1954, p. 133-136, pI. 14,
figs. 1-11.
Beedeina higoensis doii Ishii, 1958, pI. 3, fig. 1 (notdescribed) .
Beedeina higoensis (Kanmera); Suyari, 1962, p. 8, pI. 4,
figs. 6, 7; Ozawa, 1975, pI. 8, figs. 14, 15 (notdescribed); Ishibashi, 1984, p. 204-206, pI. 23, figs.
7-11, pI. 24, figs. 1-8, pI. 25, figs. 1-4.

Description:-Shell relatively large, inflated
fusiform in shape with straight axis of coiling,arched to broadly arched periphery, almost
straight lateral sides and bluntly pointed poles.
Mature specimens of 9 volutions, more than 6
mm in axial length and more than 2.5 mm inmedian width, giving approximate form ratio of
2.5.
Proloculus spherical to subspherical and 160
to 210 pm in longer diameter. Length and width
gradually increase in inner three to four
volutions, becoming nearly constant in succeeding ones, and decreasing in the outermost
one. Inner and outer volutions nearly the same intheir outlines, but with sharply pointed poles in
the former.
Spirotheca thin, approximately 30 pm inouter volutions, composed of tectum, diaphanotheca and inner and outer tectoria.
Septa narrowly spaced and intensely fluted
throughout shell, especially in polar regions. In
tunnel regions, they are unfluted and plane in
inner two to three volutions, and weakly flutedand coated with dense calcareous materials inouter ones. Septal fluting rather regular, half tothree fourth as high as chamber height, reaching
top of chambers in polar regions and producing
combination of adjacent septa. Septal countfrom the fourth to seventh volutions, 20(?), 22,
27 and 32, respectively.
Tunnel generally high and narrow, bordered439

by massive chomata. Its path rather straight, andits angle less than 20 degrees.
Remarks: - Although generic validity ofBeedeina was denied by Rozovskaya (1975) andRoss (1979), I am of an opinion that Beedeina is
phylogenetically distinguishable from Fusulina as
Ishii (1958) concluded.
The materials identified with Fusulina girtyi
from Unazawa by Huzimoto (1936) are different
from the original ones from the Middle
Pennsylvanian Brereton Limestone, Illinois ofDunbar and Condra (1928) in shape of shell andweaker septal fluting. Although any additional
materials have not been obtained from Unazawa,
Huzimoto's ones would be belonged to either
Beedeina schellwieni (Staff) or the present
species.
Occurrence:- Rare in dark gray micritic
limestone at Locs. 1 and 2 (Kawanoridani) andvery rare in light gray algal sparitic limestone at
Loc. 21 (450 m east of Mt. Komyosan).
Family Schwagerinidae Dunbar andHenbest, 1930
Genus Parafusulina Dunbar andSkinner, 1931

"Parafusulina" gigantea (Deprat)
Figure 4-18
Fusulina gigantea Deprat, 1913, p. 29, 30, pI. 1, figs.
1-6.
Schellwienia gigantea (Deprat); Ozawa, 1925, p. 32-33,
pI. 4, fig. 9.
Parafusulina gigantea (Deprat); Toriyama, 1958, p.
200-203, pI. 36, figs. 2-11; Toriyama and Sugi,
1959, p. 19-21, pI. 1, figs. 1-5; Sheng, 1963, p. 73,
201, pI. 20, figs. 1-5,9,11, pI. 21, figs. 3-5; Leven,
1967, p. 171, pI. 24, figs. 2, 3,5; Toriyama andPitakpaivan, 1973, p. 48-51, pI. 5, fIgs. 13-20; Linet al., 1977, p. 70, pI. 19, fig. 4; Toriyama andKanmera, 1979, p. 44-46, pI. 5, figs. 10-13, pI. 6,
figs. 1-6.
Pseudofusulina gigantea (Deprat); Hasegawa et al., 1979,
pI. 81, fig. 1 (not described).

Remarks:-Morphologic variation of thepresent material is uncertain because of a small
number of well-oriented sections. The illustrated
specimen is characterized by a large sub spherical

440

Fumio KOBA YASHI

856. Paleozoic Foraminifers of Ogawadani Formation
proloculus with more than 0.8 mm in its longer
diameter, thick spirotheca with very coarse
alveolar keriotheca, thick septa, somewhat
regular and high septal fold. Thick septa are due
to secondary coating of dark calcareous material.
Among the described species, the present
material is the closest to ''Parafusulina'' gigantea(Deprat), widely distributed in Southeast Asia,
South China and Pamir. In Japan, the present
species has been exclusively found in the
Akiyoshi Limestone. "P." gigantea was originallydescribed from the upper Middle Permian of
Laos (Deprat, 1913), where it occurs inassociation with Yabeina globosa (Yabe) andothers. Subsequent workers, above mentioned,
showed that this species occurred throughout
Middle Permian.
Morphologic characters, such as thick spirotheca and septa of this species are dissimilar to
those of the type species of Parafusulina.
Although this species would be referable to othergenus, the conclusion is reserved. Schwagerina
ibukiensis Kobayashi from the Ibukiyama Limestone (Kobayashi, 1957) is similar to the present
species rather than Schwagerina chiapasensis
Thompson and Miller. However, S. ibukiensis has
more regular and intense septal fold and thinnerspirotheca than those of the present species.
Occurrence:-Rare in conglomeratic limestone
at Loc. 18 (Mt. Komyosan).

~441

Parafusulina hirayuensis Igo
Figures 5-1,2

Parafusulina hirayuensis Igo, 1959, p. 250-252, pI. 4,
figs. 1-3.

Description:-Shelliarge, elongate fusiform to
sub cylindrical in shape with nearly straight axisof coiling, broadly arched to straight periphery,almost straight lateral sides and rounded tobluntly pointed poles. Mature specimens of 8 to
9 volutions, 14.5 to 15 mm in axial length and 4
to 4.5 mm in median width, giving form ratio
about 3.5.
Proloculus subspherical and 275 to 383 ,urn intheir longer diameter. The first volution oval to
inflated fusiform with rounded poles. Succeeding
three to four volutions elongate fusiform withsharply pointed poles. Radius vector 0.28, 0.42,
0.60, 0.86, 1.14, 1.45, 1.81 and 2.11 mm fromthe first to eighth volutions in the specimen
illustrated in Figure 5-1; 0.20, 0.32, 0.47, 0.69,
1.02, 1.29, 1.57, 1.91 and 2.27 mm from thefirst to nineth ones in Figure 5-2, respectively.
Spiro theca composed of thin tectum and finealveolar keriotheca. Spirothecal thickness 29, 46,
64, 77, 95, 126, 110 and 91 ,urn from the first to
eighth volutions in Figure 5-1; 28, 39, 49, 75, 97,
101, 98, 110 and 72 ,urn from the first to nineth
ones in Figure 5-2, respectively.
Septa intensely fluted throughout shell, andcoated by dark calcareous materials. Septal
folding somewhat regular and about half as highas chambers in median part of shell, but becomes
irregular and higher toward poles and highly

Figure 3. 1, 3,4. Tubertinina spp. lateral sections, 1: Loc. 10, MPC 3775, x 60; 3,4: Loc. 21, MPC 3692,
x 80.2. Radiosphaera sp., lateral section, Loc. 18, MPC 3764, x 60. 5, 6. Palaeo textularia sp. A, Loc. 21,5: MPC
3693; 6: MPC 3695, x 30. 7, 10, 12. Palaeo textularia sp. C, lateral sections, 7, 10: Loc. 13, MPC 3716, MPC
3669, x 30; x 40; 12: Loc. 14, MPC 3652, x 20. 8, 9. Cribrogenerina? sp. 8: lateral section; 9: transverse section,
both Loc. 13, MPC 3667, 8, 9a: x 30; 9b: x 40. 11. Palaeo textularia sp. B, lateral section, Loc. 2, MPC 3807, x
20. 13, 14. Abadehella coniformis Okimura and Ishii, lateral sections, Loc. 13, 13: MPC 3670; 14:
MPC 3669, x 35. 15. Pachyphloia ovata Lange, lateral section, Loc. 13, MPC 3732, x 40. 16. Fisherinidae gen. et
sp. indet., lateral section, Loc. 10, MPC 3781, x 30.17,19. Tetrataxis sp. A, lateral sections, Loc. 21,17,19:
MPC 3692, x 25. 18. Tetrataxis sp. B, lateral section, Loc. 14, MPC 3653, x 40. 20. ·Tetrataxis conica Ehrenberg,
lateral section, Loc. 14, MPC 3653, x 40. 21. Baisalina sp. cf. B. globosa Wang, lateral section, Loc. 13, MPC
3731, x 40. 22. Agathammina sp., lateral section, Loc. 12, MPC 3681, x 40. 23,24. Endothyra sp., 23: parallel
section, Loc. 10, MPC 3782, x 40; 24: tangential section, Loc. 21, MPC 3693, x 60. 25, 26. Rauserella sp.,
oblique sections, Loe. 15,25: MPC 3708; 26: MPC 3707, x 25. 27. Hemigordius? sp., lateral section, Loc. 13,
MPC 3730,.x 40.

442

Fumio KOBA YASHI

...

..

~

,~A\

', '

•

•

r-J;I

DW

~

. . . ...... .

_..

... •• ,,;

•

•

....

......... ; 4, iiI!......

,~":.:....:>-":

-

•

;.

. " -..... '1i~,.:-"";,'./ ..
• ".,.

~

,t'o

.

19

20

>

856. Paleozoic Foraminifers of Ogawadani Formation
complicated in polar regions.
Tunnel low, narrow in inner volutions, but
broad in outer ones. Rudimentary chomata
present and restricted in inner two volutions.
Lateral sides toward polar regions of inner five
volutions filled with dense deposits.
Remarks:-The present materials show considerably wide morphologic variation in size of
proloculus, radius vector, septal fluting andothers. Among the described materials, thepresent ones are the closest to Parafusulina
hirayuensis Igo, originally described from theHirayu Pass, east of Takeyama, northermost partof the Mino Terrane. The original and the present
specimens are common in large sub cylindricalshell, development of septal fluting, axial filling,
and broad and low tunnel in outer volutions.
P. hirayuensisis is similar to such forms of
Parafusulina as P. subextensa Chen, P. iisakai Igo
and Ogawa and P. hayashii Igo. From the
Akasaka Limestone, Morikawa (1958) proposed
many new species referable to Parafusulina, someof which are allied to hirayuensis. However, mostof them are insufficient to compare theirmorphologic characters in specific level.
Occurrence:-Rare in gray micritic limestone
at Loc. 15 (430 m northwest ofMt. Komyosan).
Family Verbeekinidae Staff and
Wedekind, 1910
Subfamily Verbeekininae Staff and
Wedekind, 1910
Genus Verbeekina Staff, 1909

Verbeekina verbeeki (Geinitz)
Figures 5-3,4Remarks:-This species is one of the mostwell-known fusulinacean species in the Tethyan~

443

Province. The following synonym list of thisspecies is presented after Toriyama and Kanmera(1977);
Lin et al., 1977, p. 83, pI. 25, fig. 9; Liu et al., 1978, p.
81, pI. 18, fig. 17; Ding, 1978, pI. 100, fig. 2 (notdescribed); Kobayashi, 1979, pI. 4, figs. 9, 10 (notdescribed); Hasegawa et ai., 1979, pI. 85, figs. 1-5,7(not described); Tien, 1979, p. 130-132, pI. 21, figs.
3-9; Wang et ai., 1981, p. 58, 59, pI. 19, fig. 6;
Wang et ai., 1982, p. 99, pI. 27, figs. 1,2; Xie, 1982,
pI. 32, fig. 3 (not described); Sun et ai., 1983, p. 33,
pI. 9, fig. 5; Ishibashi, 1986, p. 105-107, pI. 15, figs.
2-8, pI. 16, figs. 1-3; Kobayashi, 1986, p. 145, pI.
4, fig. 8, pI. 9, fig. 6.

Occurrence:-Rare in gray sparitic limestone
at Loc. 13 (Mitsugo Limestone Cave) andconglomeratic limestone at Loc. 18 (Mt.
Komyosan).
Subfamily Misellininae
Miklukho-Maklay, 1958
Genus Pseudodoliolina Yabe and Hanzawa,
1932

Pseudodoliolina pseudolepida (Deprat)
Figures 6-1a-8

Remarks:-The present materials are identicalwith the original ones by Deprat (1912) except
for higher and narrower parachomata of theformer. Small and narrow calcareous deposits
occasionally present at the top of chamber inouter volutions.
Pseudodoliolina pseudolepida is widespread,especially in Japan, South China and Southeast
Asia. After the description of this species by
Toriyama and Kanmera (1977), the synonym listof this species is as follows:
Liu et ai., 1978, p. 83, pI. 20, fig. 5; Ding, 1978, p. 288,
pI. 98, fig. 6; Toriyama and Kanmera, 1979, p.

Figure 4. 1,2. Dunbaruia schubertellaeformis Sheng, 1: axial section, Loc. 12, MPC 3681; 2: tangential
section, Loc. 13, MPC 3668, both x 40. 3,5. Neofusulinella sp., 3: tangential section, MPC 3635, x 40; 5:parallel section, MPC 3765, x 30 both Loc. 18.4. Dunbarula? sp., tangential section, Loc. 14, MPC 3653, x 40.
6. Yangchienia compressa (Ozawa), axial section, Loc. 18, MPC 3632, x 15. 7-17. Beedeina higoensis (Kanmera)
7,10,11,16: tangential sections; 8,12-15,17: oblique sections; 9: sagittal section, 7: Loc. 1; 8-10,12-16;
Loc. 2; 11, 17: Loc. 21, 7-17: MPC 3822; 3828; 3828; 2823; 3691; 3826; 3828; 3825; 3824; 3827; 3693, 7: x
IS; 8-10,12,14-16: x 11; 11, 13, 17: x 10.18. "Parafusulina" gigantea (Deprat), axial section, Loc. 18, MPC
3630, x 10. 19,20. Chusenella spp., 19: tangential section, Loc. 13; MPC 3728; 20: sagittal section, Loc. 18,
MPC 3765, both x 10.

444

Fumio KOBA YA SH!

Figure 5. 1 , 2. ParafllslIlina hiraY lIensis [go, axial sec tions, Loc. 15 , 1: MPC 3707; 2: MPC 3708 , x 10. 3,
4. Verbeekina verbeeki (G einitz) , 3 : tangential section, MPC 3715 ; 4 : axial section, MPC 37 16 , both Loc. 13 , x
10.

856. Paleozoic Foraminifers ofOgawadani Formation
54-56, pI. 8, figs. 7-13; Hasegawa et aZ., 1979, pI.
83, figs. 1, 2, 4 (not described); Tien, 1979, p.
132-134, pI. 20, figs. 4-6; Li et aZ., 1979, pI. 2, fig.
5 (not described, the same as PI. 2, fig. 2 of Han,
1985); Sun et aZ., 1983, p. 37, pI. 9, fig. 3; Han,
1985, p. 684, pI. 2, figs. 2-4.

Occurrence:-Conunon in gray sparitic limestone at Loc. 13 (Mitsugo Limestone Cave) andrare in conglomeratic limestone at Loc. 18 (Mt.
Komyosan).
Family Neoschwagerinidae Dunbar andCondra, 1928
Subfamily Neoschwagerininae Dunbar andCondra, 1928
Genus Neoschwagerina Yabe, 1903

N eoschwagerina craticulifera (Schwager)
Figures 6-13-16, 18, 19; 7-1

Remarks:-The present specimens resemble
most of those described from the various
localities within the Tethyan Province. However,those described from Jilin, Northeast China(Han, 1980) and from Xizang (Tibet) (Chu,1982) ·are excluded from this species. Two
illustrations (PI. 33, figs. 9, 10) among the three(PI. 33, figs. 9-11) from Jilin are referable to
the genus Lepidolina, and the other would be
assignable to other species of Neoschwagerina.
The Xizang material is also referable to the genus
Lepidolina. The following synonym list of thisspecies is followed by Toriyama and Kanmera(1977):
Lin et aZ., 1977, p. 90, pI. 28, fig. 13; Liu et aZ., 1978, p.
89, pI. 21, fig. 11; Toriyama and Kanmera, 1979, p.
74-77, pI. 12, figs. 11-18; Kobayashi, 1979, pI. 4,
figs. 6-8 (not described); Hasegawa et aZ., 1979, pI.
84, figs. 9-17 (not described); Wang etaZ., 1982, p.
105, pI. 29, fig. 7; Xie, 1982, p. 69, pI. 33, fig. 12;
Sun et aZ., 1983, p. 38, pI. 10, figs. 2, 12; Ishibashi,
1983, pI. 13, figs. 10-12 (not described); Ishibashi,
1986, p. 108, 109, pI. 17, figs. 1-12.

Occurrence:-Conunon in gray micritic limestone at Loc. 7 (280 m SSW of Mt. Shiroyama),
very rare in gray oolitic limestone at Loc. 9 (1.8km WNW of Mt. Mitake) and conunon in
conglomeratic limestone at Loc. 18 (Mt.

445

Komyosan).

N eoschwagerina haydeni Du tkevich andKhabakov
Figures 7-2a-b-11

Neoschwagerina craticulifera haydeni Dutkevich andKhabakov; Thompson, 1946, p. 155, 156, pI. 23,
figs. 12, 13; Kanmera, 1957, pI. 19, fig. 24 (notdescribed; the same as Thompson, 1946, pI. 23, fig.
12); Toriyama, 1958, p. 220-223, pI. 41, figs. 6-8;
Suyari, 1962, p. 35, 36, pI. 11, fig. 5; Ishizaki 1962,
p. 173-175, pI. 12, figs. 4-6.
Neoschwagerina haydeni Dutkevich and Khabakov;
Honjo, 1959, p. 147-149, pI. 3, fig. 10; Minato andHonjo, 1959, pI. 3, fig. 2 (not described); Sheng,
1963, p. 103, 104,236,237, pI. 32, figs. 1-8; Zhang
and Wang, 1974, p. 292, pI. 151, fig. 7; Liu et aZ.,
1978, p. 89, pI. 21, fig. 6; Toriyama and Kanmera,
1979, p. 77 -80, pI. 12, figs. 19-22, pI. 13, figs.
1-8; Hasegawa et aZ., 1979, pI. 84, figs. 1-8 (notdescribed); Wang et aZ., 1981, p. 63, pI. 15, figs. 1, 2,
5, 7; Wang et aZ., 1982, p. 106, pI. 30, fig. 7; Sun etaZ., 1983, p. 39, pI. 10, fig. 13.
Neoschwagerina cf. haydeni Dutkevich and Khabakov;
Ding, 1978, pI. 101, fig. 2 (not described).

Description:-Shell inflated fusiform withnearly straight axis of coiling, broadly archedperiphery, straight lateral sides and roundedpoles. Mature shell of 14 to 15 volutions,approximately 6 to 8 nun in axial length and 4.4
to 5.5 nun in median width, giving form ratio
about 1.4.
Proloculus spherical, minute and about 40 to
90 pm in diameter. The first one to one and ahalf volutions ellipsoidal with short axis ofcoiling. The second to seventh volutions fusiform
to inflated fusiform with pointed to bluntly
pOinted poles, gradually increasing their height
and width. Beyond the eighth volution, height ofvolution becomes nearly the same. From the firstto eleventh volutions of the specimen illustrated
in Figure 7-2a-b, axial length 0.03, ?, 0.15, 0.26,
0.41, 0.64, 0.90, 1.20, 1.56, 1.81 and 2.07 nun;radius vector 0.07,0.09,0.15,0.22, 0.31, 0.45,
0.63,0.81, 1.01, 1.23 and 1.44 nun, respectively.
From the first to twelveth volutions of thespecimen illustrated in Figure 7-3, axial length
0.05, 0.14, 0.23, 0.43, 0.59, 0.80, 0.98, 1.17,
1.47, 1.77, 2.06 and 2.29 nun; radius vector

446

Fumio KOBA YA SHI

856. Paleozoic Foraminifers o[ Ogawadani Formation
0.08, 0.12, 0.20, 0.29, 0.41, 0.55, 0.68, 0.84,
1.04, 1.25, 1.47 and 1.68 rnm, respectively.
Spirotheca composed of tectum and thickfinely alveolar keriotheca except for juvenile
volutions. Spirothecal thickness from the third toeleventh volutions 22, 26, 35, 48, 74, 62, 111,
51 and 65 pm in the specimen illustrated in
Figure 7-2a-b. Septal count attains 30 to 34 in
the tenth volution. Between the adjacent septa,
axial septula well developed. Axial septula first
appear in the fifty vol uti on. Their number
gradually increases ontogenetically. Two, rarely
one, axial septula regularly arranged between
adjacent septa in the thirteenth and later ones.
Primary transverse septula well developed
throughout shell except for juvenile volutions.
They are broad and triangular or fan-shaped incross section. Combination of well-developed
primary transverse septula and axial septula
subdivides each chamber into ellipsoidal torectangular chamberlets. Secondary transverse
septula first appeared in peripheral parts of thethirteenth volution, but absent in median part ofshell.
Parachomata massive and high, more than half
as high as chambers in places. In such cases,
parachomata are connected with lower end ofprimary transverse septula. Foramina elliptical tocircular, open at basal part of septa in crosssections.
Remarks:-Among the described materials,
the Chinese ones from the Maokou Limestone of
Guizhou (Sheng, 1963) most closely resembles
the present ones in shape and size of shell,
development of septula and parachomata.
N. haydeni is closely related to N. craticuli[era, but the former can be distinguished fromthe latter in having larger shell, more number ofvolutions and well-developed septula. N. haydeni
is allied to N. margaritae Deprat in development447

of both axial and transverse septula. The two
occur nearly the same stratigraphic level. The
former is easily distinguished from the latter instraight lateral sides and more pointed poles ofeach volution.
Occurrence:-Cornmon to rate in graymicritic, partly dolomitic, limestone at Loc. 12(Otakezawa Limestone Cave) and abundant tocommon in gray micritic and sparitic limestones
at Loc. 13 (Mitsugo Limestone Cave).

Neoschwagerina simplex Ozawa
Figure 6-17

Neoschwagerina simplex Ozawa, 1927, p. 153, 154, pl.
34, figs. 7-11, 22, 23, pI. 37, figs. 3a, 6a; Chen,
1956, p. 55, 56, pI. 12, figs. 13-16; Honjo, 1959, p.
139-142, pI. 3, figs. 1, 4, 5, pI. 4; Minato andHonjo, 1959, pI. 1, fig. 2 (not described); Suyari,
1962, p. 36, pI. 11, fig. 1; Kanmera, 1963, p. 112,
113, pI. 13, figs. 1-6, pI. 14, figs. 1-6, pI. 19, fig.
15; Leven, 1967, p. 189, 190, pI. 32, figs. 8-10;
Ozawa, 1970, pI. 4, figs. 9 (the same as pI. 10, fig. 16
of Ozawa, 1975), 10 (not described); Lin et al.,
1977, p. 91, pI. 28, fig. 3; Liu et al., 1978, p. 90, pI.
21, fig. 8; Sashida, 1980, p. 305, 306, pI. 35, figs.
8-10.
Neoschwagerina cf. simplex Ozawa; Kanmera, 1957, pl.
20, fig. 1 (not described); Kanuma, 1960, p. 67,68,
pl. 11, figs. 1, 10, 11.
Neoschwagerina sphaerica (Maklay); Honjo, 1959, p.
159, pI. 3, fig. 3.
Neoschwagerina simplex simplex Ozawa; Toriyama,
1975, p. 99-101, pl. 19, figs. 25-28, pl. 20, figs.
1-21.
Neoschwagerina simplex tenuis Toriyama and Kanmera;
Toriyama, 1975, p. 97 -99, pI. 19, figs. 14-24.
Neoschwagerina cf. simplex tenuis Toriyama andKanmera; Toriyama and Kanmera, 1979, p. 74, pI.
12, fig. 10.
? Neoschwagerina simplex simplex Ozawa; Li et al.,
1979, pI. 2, fig. 8 (not described, the same as PI. 2,
fig. 11 of Han, 1985, p. 685).
non. Neoschwagerina simplex Ozawa; Han, 1980, p. 90,
pI. 33, figs. 7, 8.

+- Figure 6. la-8. Pseudodoliolina pseudolepida (Deprat), 1,2,7: axial sections; 3: sagittal section; 4,5:
tangential sections; 6: parallel section; 8: oblique section, 1-6: Loc. 13; 7, 8: Loc. 18, 1-8: MPC 3666; 3722;
3665; 3668; 3723; 3724; 3729; 3633, all x 10 except for 1b: x 20. 9-12. Neoschwagerina sp. A, axial sections,Loc. 18,9-12: MPC 3761; 3764; 3762; 3631, x 10. 13-16,18,19. Neoschwagerina craticulifera (Schwager),13, 16: oblique sections; 14, 15: axial sections; 18, 19; sagittal sections, all from Loc. 18 except for 19: Loc. 9,13-16: MPC 3634; 3629; 3628; 3763; 18: MPC 3627; 19: MPC 3801, x 10. 17. Neoschwagerina simplex Ozawa,
tangential section, Loc. 18, MPC 3760, x 10.

448

Fumio KOBA YASHI

856. Paleozoic Foraminifers of Ogawadani Formation
Remarks:-Honjo (1959) described the topotype materials of this species. He designated thelectotype for the specimen illustrated as fig. 8 of
PI. 34 (incomplete axial section) of Ozawa(1927), and also noticed the absence of
secondary transverse septula of this species.
Whereas, the terms of "septa", "axial septula"and "secondary axial septUla" of Honjo (1959)
were in confusion in his description. His"secondary axial septUla" should be restrictedly
defined as axial septula according to his not
fully-grown sagittal section (Honjo, 1959, PI. 3,
fig. 5). This is also comprehensible from Ozawa's
original description, in which mentioned is"auxiliary meridional septa rarely found in later
whorls".
Simple framework of septula, rather thickspirotheca and prominent parachomata of the
Ogawadani materials are similar to Neoschwagerina simplex rather than N. craticulifera.
However, the present materials have larger shellthan original ones. Specific as well as genericassignment is doubtful of the specimen identified
with Cancellina primigena (Hayden) by Huzimoto (1936) from Mt. Komyosan. The illustrated specimen has stout and short primarytransverse septUla, massive parachomata andrather thick spirotheca. These characters are
diagnostic to Maklaya or primitive species of
Neoschwagerina rather than Cancellina. Morenumber of specimens are required for further
comparisons.
N. spherica (Maklay) described from the
Akasaka Limestone (Honjo, 1959) and N.
simplex tenuis Toriyama and Kanmera from theRat Buri Limestone of Thailand (Toriyama,1975) are considered to be junior synonym of
the present species based on their stratigraphic
occurrences and morphologic characters. Two
illustrated specimens described from Northeast
China by Han (1980) are slightly deformed andabraded in their outer volutions. Han's materials are not referable to N. simplex on the449basis of their well-developed transverse septula.
Occurrence:-Rare in conglomeratic limestone
at Loc. 18 (Mt. Komyosan).

N eoschwagerina sp. A
Figures 6-9-12

Remarks:-Development and shape of septula
and parachomata and thin spirotheca of thepresent materials resemble those of such speciesof Cancellina as C. tenuitesta Kanmera and C.
akasakensis (Morikawa and Suzuki). The former
species was described from the Kozaki F ormation in association with Neoschwagerina simplex
Ozawa (Kanmera, 1963). The latter species was
proposed by Morikawa and Suzuki (1961) as
Neoschwagerina akasakensis from the sixth zone
(Neoschwagerina rotunda Zone) of the Akasaka
Limestone which was subdivided into fifteen
fusulinacean zones by Morikawa (1958).
On the contrary, endothyroid coiling in initialstage of the present materials is diagnostic to
Neoschwagerininae. Endothyroid coiling is lackin genera referable to Lepidolininae including
Cancellina except for their microspheric forms.
This unnamed species is, accordingly, notassignable to Cancellina but Neoschwagerina.
The present materials may be representative of
inner volutions of N. craticulifera. However, it isless possible on the basis that they are notco-existed with N. craticulifera in the same
limestone block. Spirothecal thickness, shape of
septUla and parachomata are different between
the two.
Occurrence:-Common to rare in conglomeratic limestone at Loc. 18 (Mt. Komyosan).
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Chu, S. F. (1982): Lower Permian fusulinids fromLhunzhub County, Xizang (Tibet). Contrib. Geol.

+- Figure 7. 1. Neoschwagerina craticulifera (Schwager), enlarged photograph of Fig. 6-15, x 20. 2a-I1.
Neoschwagerina haydeni Dutkevich and Khabakov, 2-7: axial sections; 8.10,11: sagittal sections; 9: parallel
section, Loc. 13,2-11: MPC 3720; 3721; 3717; 3714; 3664; 3725; 3727; 3712; 3719; 3663, all x 10 except for
2a and 3a: x 20.

450

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Fusulinids from Xizang of China. In, Nanjing Inst.
Geol. Paleont. ed., Paleontology of Xizang, Book3, p. 1-80, pIs. 1-21. Scientific Publishing House,
Beijing. (in Chinese with English abstract)
Xie, S. G. (1982): Protozoa. In, Geol. Bureau, Hunaned., The Palaeontological Atlas of Hunan, Geol.
Mem., Ser. 2, no. 1, p. 2-73, pIs. 1-35. Geological
Publishing House, Beijing. (in Chinese)
Zhang, L. X. and Wang, Y. J. (1974): Permian
Fusulinida. In, Nanjing Inst. Geol. Paleont. ed.,Stratigraphical and Paleontological Atlas of WestSouth China, p. 289-296, pIs. 150-153. Scientific
Publishing House, Beijing. (in Chinese)

Akasaka w-iffi., Akiyoshi tktf, Aterazawa ~~rR, Chichibu fJ(X, Gozenyama 1alJiltrilJ, Hikawa
7kJII, Hirayu -'f~, Ibukiyama {jI"(;!(:ilJ, Kawanoridani JII~~, Komyosan ~!lJlilJ, Kozaki 'NiIf,
Mino ~., Mitake 1alJ-ffi. Mitsugo =:",m. Nippara SW-. Ogawadani 'NII~. Okutama ~~ ••Otakezawa ::k-ffirR. Shiromaru 811.. Shiroyama ~ilJ. Takayama ~ilJ. Tamagawa ~.JlI.
Torinosu ~/:ll. Unazawa #ii:rR.

~JRilJj-1!!l¥H'fll'NlI~)jggO)J5"1:.f(:~JtIl1HL~ ftE : ~JRilJ!l!!0)fJ(X1IH¥Hi1~.Rl1:-t 7.> 'NII~)jO)
EEJ(!67 P ", !ltJ-t:J. 32~47~O)EER*C<PJtIl~--:'}v.l>.*c<pJtIlO)fifL~ftEtJ~~liU~.ht.:o ::.ht:J~ !! A r -t 7.> C c t tc:. 7 ;;<:: !! T~f4tc:. ~ i .h 7.> 5 ~ 9 ~ : Beedeina higoensis (Kanmera).

"Para/usulina" gigantea (Deprat). P. hirayuensis Igo. Verbeekina uerbeeki (Geinitz).
Pseudodoliolina pseudolepida (Deprat). Neoschwagerina craticuli/era (Schwager). N.
haydeni Dutkevich and Khabakov. N. simplex Ozawa. N. sp. A ~~tIt L. t.:o'N*X7cTrans. Proc. Palaeont. Soc. Japan, N.S., No. 150, pp. 453-464,7 Figs., June 30, 1988

857. PERMIAN SPIDNCTOZOAN SPONGES FROM THE
ICHINOTANI FORMATION, HIDA MASSIF,CENTRAL JAPANHISA YOSHI IGO
Institute of Geoscience, University of Tsukuba, Ibaraki 305

HISAHARU IGO
Department of Astronomy and Earth Sciences,
Tokyo Gakugei University, Koganei, Tokyo 184
andSHUKO ADACHI
Institute of Geoscience, University of Tsukuba, Ibaraki 305

Abstract. Two new Permian sphinctozoan sponges, Cystauletes kingi and Amblysiphonella hidensis are described from the uppermost part of the Ichinotani Formation whichcrops out in the Mizuyagadani valley, Fukuji, Hida Massif, central Japan. The genus Cystauletes
was first introduced by King from the Desmoinesian of Oklahoma, U.S.A. and Cystauletes
mammilosus King was described as a mono typic species of this genus. The present new species ischaracterized by larger size than the American species. Amblysiphonella hidensis ischaracterized by high chambers with rather thin exowalls as compared with other species of thisgenus.

Introduction

additional regions, such as Sicily, Italy (Parona,1933); Karawanken, Austria (peltzmann, 1930);
Kwangsi, China (Yii, 1935); Texas and otherstates of U.S.A. (King, 1933, 1943, etc.)_
After World War II, Termier and Termier(1955, 1977), Termier, Termier and Vachard(1977) contributed to the study of Upper
Paleozoic sponges on the basis of rich collections
from Tunisia. Finks (1960) also published acomprehensive monographic study of Upper
Paleozoic siliceous sponges from the Texas
region, and he (Finks, 1970) also discussed someinteresting problems concerning evolution andhistory of Paleozoic sponges. Seilacher (1962)
proposed a new major classification of calcareous

Upper Paleozoic sponges were introduced by
the classical works of Zittel (1877, 1878),
Steinmann (1882), Waagen and Wentzel (1887),
and Hinde (1888). Subsequently, Girty (1908)
described Permian sponges from the Guadalupe
Mountains of Texas and he proposed several new
genera. Mansuy (1913, 1914) described some
Permian sponges from Indochina. Gerth (1929)
introduced a rich Permian sponge fauna from
Timor including several new genera and species.
In the 1930's to 1940's Carboniferous andPermian sponges were described from various* Received December 17,1987; accepted May 30, 1988
453

454

Hisayoshi IGO et al.

sponges.
Recently, Permian sponges have been described from China (Deng, 1981, 1982) and
Venezuela (Rigby, 1984). Rigby and Potter(1986) reported an interesting Ordovician sponge
fauna from northern California and theydescribed many new forms and discussed
phylogeny of the Lower and Middle Paleozoic
genera. Their report is also very informative in
discussions of phylogeny of Upper Paleozoic
forms. Aleotti, Dieci and Russo (1986) restudied
Permian sphinctozoan sponges from Sicily thatwere previously reported by Parona (1933).
These current studies, mentioned above, contributed to our understanding of many paleontological problems of the Upper Paleozoic sphinctozoan sponge faunas. However, our knowledge
concerning sponge faunas, in general, is still
limited when compared with most of other
Upper Paleozoic invertebrate fossil groups.
Common occurrences of fossil sponges havebeen known from Japanese Upper Paleozoic
limestones and coherent sedimentary rocks,
however, these fossils were largely ignored bymost Japanese paleontologists. Yabe (1902) firstpointed out the occurrence of Permian calcareous sponges from Japan. Subsequently,
Hayasaka (1918, 1923) studied some Upper
Paleozoic calcareous sponges collected from
China and Japan. Yabe and Sugiyama (1934)
described two new species of Amblysiphonella
and proposed a new genus, Rhabdactinia, from
Permian rocks of Shikoku. The same authors
described several species of what they termed
stromatoporoids from Permian of Japan (Yabeand Sugiyama, 1930, 1933). Some of these are
now known not to be stromatoporoids (Mori,
1980), and some of them seem to be calcareoussponges. Inai (1936) proposed a new Carboniferous genus, Discosiphonella, from northeast
China. Akagi (1958) described a new Permian
species from west Japan. Most of the described
Upper Paleozoic sponges in Japan are species of

Amblysiphonella.
As will be mentioned later, our material wascollected from the Lower Permian of theuppermost Ichinotani Formation exposed in the

Fukuji area, Hida Massif, central Japan. It
includes a new species of Cystauletes, which until
now has been known only from the Pennsylvanian of Oklahoma, U.S.A. This paper is, thus,
the second report of the occurrence of thisgenus, which seems to be noteworthy. The othersphinctozoan sponge associated with this new
species is a new species of Amblysiphonella,
which is the most commonly reported genus in
Permian rocks of Japan and the Tethyan faunal
realm.
Acknowledgment
We thank Professor J. Keith Rigby, Department of Geology, Brigham Young University,
Provo, Utah, who read the manuscript andoffered many helpful comments. We acknowledge the support of this research by the
Grant-in-Aid for Scientific Research from the
Ministry of Education, Science and Culture,
Japanese Government (No. 62540597).
Geologic setting
The Ichinotani Formation crops out along the
Ichinotani, Mizuyagadani and Mizuboradani
valleys, in the Fukuji area, Hida Massif, central
Japan. This formation consists mainly of
limestone and subordinate shale and tuff. Mostof the limestones are fossiliferous, well bedded
and dark gray to black, with interbeds of pale
gray, massive to thickly bedded limestones.
Stratigraphic and paleontologic investigations
have previously concerned fusulinaceans, smaller
foraminifers, corals, cephalopods, calcareous
algae and other minor groups. They have beenstudied by several specialists, such as Igo (1957),
Kato (1959), Niikawa (1978), Adachi (1985),
Niko (1986), Niko and Hamada (1987) andmany others. These studies proved that thegeologic age of the Ichinotani Formation ranges
from the latest Visean through the Early Permian
Asselian.
The present sponges came from the uppermost part of the Ichinotani Formation whichcrops out along the lower reaches of theMizuyagadani valley (Figure 1). Limestone beds

857. Permian sponges from Hida

Figure 1.

at this outcrop are abundantly fossiliferous,
thickly bedded to massive and mostly pale gray,but frequently include pale red and pale green
muddy material, and are approximately 5mthick. They yield abundant calcareous algae,
fusulinaceans, smaller foraminifers, sponges,
bryozoans and crinoid stems, with subordinate
associations of pelecypods, gastropods, nautiloids, and brachiopods. The gelogic age of theselimestone beds is thought to be Asselian on thebasis of the occurrence of Quasifusulina longissima ultima Kanmera. Furthermore, these beds
immediately overlie limestones containing
Pseudoschwagerina morikawai Igo, which is themost characteristic species of the basal Permianof the Ichinotani Formation. The beds also areconformably overlain by the Mizuyagadani
Formation which consists of calcareous tuff, andalternating sandstone, shale and siliceous tuff.
The Mizuyagadani Formation yields corals,

455

Locality map.

brachiopods, orthoceratids and radiolarians
which indicate a Sakmarian age (Igo, 1959, Nikoetal., 1987, Niko, 1987).
Sphinctozoan sponges are particularly abundant approximately in the middle of the 5 meters
limestone beds, but they are very difficult toseparate from limestone. Most specimens on theweathered surface show pale red because they areowing coated by oxidized muddy material.
Sponge bodies are filled with calcareous mud,including fragments of various fossils. Central
tubes of some specimens were partly filled withsparry calcite and lime mud, showing geopetal
structures. Sessile foraminifers, Tuberitina, andcalcareous algae are attached to endowall
surfaces of some specimens. The sedimentary
environments of this limestone are thought to bevery shallow back reef lagoonal sea on the basisof limestone lithology and paleontologic evidence.

Hisayoshi IGO et al.

456

B
A
Figures 2A, B. Cystauletes kingi Igo, Igo and Adachi, n. sp. A, a part of the body
restored from the serial sections of paratype; B, branched bodies restored from the holotype; scale bar is 1 cm.

Description of species
Class Calcarea Bowerbank, 1884
Order Sphinctozoa Steinmann, 1882
Suborder Porata Seilacher, 1962
Family Cystothalamiidae Girty, 1908
Genus Cystauletes King, 1943
Cystauletes kingi Igo, Igo and Adachi, n. sp.
Figures 2A-B; 4-1a-2c; 5-1a-3; 6-1a-3b

Diagnosis.-Cystauletes having a large bifurcated cylindrical body, about 3 cm in diameter.
Entire body dendroid and may be about 10 cm
long. Central tube also large, about 1.5 cm indiameter. Spherical to sub spherical and glome rated chambers diagonally arranged and partly
overlapping, and about 1.0 em in diameter. Wall
perforated by numerous pores of about 0.4 mm
in diameter.
Description.-Sponges consist of almost
straight or slightly sinuous and distally branching

Figure 3. Amblysiphonella hidensis,
Igo, Igo and Adachi, n. sp. A part of the
body restored from the holotype; scalebar is 1 cm.

cylindrical bodies 2.5 to 3.5 cm in diameter.
Proximal portion of sponge is more or lesstapered and its diameter increases slightly with---+ Figure 4. Cystauletes king; Igo, Igo and Adachi, n. sp. la-2c, holotype, Reg. no. IGUT 5380; laolongitudinal section of bifurcated bodies; lb, enlarged from a part of right body of la showing meshwork andvermiform patterns of endopores; 2a, horizontal section of bifurcated bodies; 2b, enlarged from a part of middle
body showing detailed feature of pores of wall; 2e, enlarged from a part of upper right body of 2a showing
structure of exowall and endowall; white lines enclosed in la and 2a indicate enlarged portion; all scale bars are
5.0mm.

857. Pem1ian sponges from Hida

45 7

458

Hisayoshi [GO et al.

growth. Branching is bifurcate at about 10
degrees. Thrice-bifurcate branching is observed in
the holotype, but the last bifurcation isrepresented by a small incipient bud. Complete
sponges are unknown in our collection, but total
lengths may attain about 10 cm.
Chambers are numerous, spherical to subspherical, glomerated and diagonally arranged.
They partly overlap each other, therefore,chambers appear in two rows in the horizontal
section and in three rows in most tangential
sections. Diameters of chambers are 0.8 to 1.1
cm, measured at right angles to the long axis.
Exowalls and interwalls of chambers are
perforated by numerous exopores and interpores,
0.35 to 0.50 mm in diameter. Exopores aredensely disposed and are mostly circular pits
surrounded by low rims on weathered surfaces ofchambers. Exopores and interpores are notsimple pores, but some of them bifurcate withinwalls or others irregularly penetrate into walls.
The retrosiphonate central tube is almost
straight or slightly sinuous. It ranges 1.0 to 1.3
em in diameter and does not have any partitions.
The endowall is 1.0 to 1.8 mm thick andperforated by numerous endopores. Endoporesare almost the same size as the exopores andinterpores, but are more densely and irregularly
disposed. Endopores appear as vermiform andmeshwork patterns in sections of the walls.
Exowalls and endowalls consist of mosaics ofsparry calcite and their surfaces are coated byvery thin dark layers.
Remarks.-All the specimens could not be
separated from the enclosing matrix, therefore,
we prepared thin and polished sections, including
several serial sections. The present new species issimilar to Cystauletes mammilosus King, which
was described from the Pawnee Limestone,
Marmaton Group, Desmoinesian Series, Pennsylvanian of Oklahoma, U.S.A. However, thisAmerican species was not well illustrated anddetailed comparison of the internal structuresand branching of the body is difficult. However,the present new species has a much larger body,chamber and central tube than in the American
species. Also the chambers of our Japanese species
are more spherical than those in C. mammilosus.
The species is named in honor of Ralph H.
King who established this genus in 1943.
Material.-The holotype, Reg. no. IGUT
5380, and 5 paratypes, Reg. nos. IGUT 5381 5385, are all stored at the Institute of
Geoscience, University of Tsukuba. All specimens were collected from the uppermost part of
the Ichinotani Formation, the Mizuyagadani
valley, Fukuji, Gifu Prefecture.
Family Sebargasiidae Steinmann, 1882
Genus Amblysiphonella Steinmann, 1882

Amblysiphonella hidensis Igo, Igo andAdachi, n. sp.
Figures 3; 7-la-3b

Diagnosis.-Amblysiphonella having a weakly
annulated, large cylindrical and branching body,
1.6 to 2.0 cm in diameter and may be up to 10.0
cm in long. Retrosiphonate central tube 4.0 to
7.0 mm in diameter and surrounded by annularlarge chambers. Rather large hemisphericalvesiculae developed in both chambers and central
tube. Perforated walls rather thin, less than 1.0mm thick.
Description:-Sponges having cylindrical,
slightly annulated and almost straight body anddistally branching. Entire body is not preserved,
but tapers slightly proximaly and ranges from 1.6·to 2.4 cm in diameter and may be more than 8.0
em long. Branching is bifurcate at rather narrowangles of about 10 degrees. Our specimens
branch only once.
A retrosiphonate central tube extends
throughout the sponge and is almost straight or~ Figure 5.
Cystauletes kingi Igo, Igo and Adachi, n. sp. la-2b, paratype, Reg. no. IGUT 5381; la, 2a, twohorizontal sections of the same individual showing geopetal texture; Ib, 2b, enlarged from a part of body of laand 2b showing detailed feature of pores of wall; 3, paratype, Reg. no. IGUT 5382; oblique horizontal andlongitudinal sections of the same individual; white lines enclosed in la and 2a indicate enlarged portion; all scalebars are 5.0 mm.

857. Permian sponges from Hida

459

460

Hisayoshi leo et al.

857. Permian sponges from Hida
slightly sinuous, with a diameter of 5.3 to 7.7
mm. The endowall is more or less variable inthickness and is 0.30 to 0.60 mm thick.
Chambers around the central tube are weakly
annulated. They are high and subquadrate incross section with a slightly arched top and basein longitudinal section. They are 5.0 to 7.0 mm
wide and 7.6 to 9.2 mm high. Rather large
hemispherical vesicles are developed in chambers
and have a thin dark inner layer. Rather stout
exaules are developed on the surface of exowall.
Basal diameters of exaules are about 1.0 mm andare covered with a cribribulla, but its length isuncertain.
Exowalls and interwalls are rather thincompared with the size of sponge body, for they
are only 0.63 to 1.00 mm thick. They are
perforated by numerous pores, 0.20 to 0.26 mm
in diameter. These pores are circular to
subcircular and some exopores have a low rim.
Endopores are almost the same size and shape as
the exopores.
Remarks.-The present new species is similar
to Amhlysiphonella dichotoma (Y abe) describedfrom Kobama and Yakejima of Okatsu, southern
Kitakami Mountains (Yabe, 1902; Hayasaka,1918), but the former has a larger body, thinnerwalls and higher chambers. Furthermore, A.
dichotoma has well developed diaphragms in thecentral tube and chambers. Amhlysiphonellasikokuensis Yabe and Sugiyama, reported from
Mimikiri, Sakawa of Kochi Prefecture (Yabe andSugiyama, 1934), also resembles the present new
species, but the former has well developed
diaphragms and smaller chambers and central
tube. Walls of the two previously known species
have a median dark line, but the present new
species has a dark thin inner layer.
Amhlysiphonella asiatica Vii, described from
En-young-hsien, Kwangsi Province, southern
China, is similar to the present Japanese species,
but the former has a larger body and traces of+-- Figure 6.

461

horizontal diaphragms in the central tube. A.
vesiculosa Waagen and Wentzel, described fromthe Salt Range (Waagen and Wentzel, 1887) andGuangxi, China (Deng, 1981), resembles thepresent new species. However, the former has alarger body and thicker walls and morewell-developed vesiculae. A. jiaojiaensis Deng(1982), reported from southwest China, is similar
to our present species in dimensions, however,the former has a slightly larger body and lower
chambers than in our species. The diameter ofcentral tube of A. jiaojiaensis is characteristicallysmall in comparison to the diameter of body. A.
markamensis Deng, introduced from the same
locality, is also similar to our species, however,the latter has a more slender central tube andhigher chambers.
Material.-The holotype, IGUT 5386, and oneparatype IGUT 5387, stored at the Institute of
Geoscience, University of Tsukuba. All specimens were collected from the uppermost part of
the Ichinotani Formation, the Mizuyagadani
valley, Fukuji, Gifu Prefecture.
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462

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no. IGUT 5387; 2a, horizontal section of bifurcated bodies; 2b, enlarged from a part of right body; white lines
enclosed indicate enlarged portion; all scale bars are 5.0 mm.

HisayoshiIGO et aZ.

464

Anthracolithic fauna of Japan. Jour. Geol. Soc.
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- - and - - (1933): Discovery of Amphipora andClathrodictyon in the Permian of Japan. Ibid., vol.
11, nos. 1-2, p. 19-23, 3 fIgs.
and - - (1934): Amblysiphonella and Rhadactinia gen. et sp. nov. from the Upper Paleozoic
limestone of Mimikiri, near Sakawa-machi, Tosa

Provo Sikoku, Japan. Ibid., vol. 11, nos. 3-4, p.
175 -180, pis. 20-22.
Yu, C. C. (1935): On Amblysiphonella asiatica sp. nov.
a remarkable sponge. Geol. Soc. China, Bull., vol.
14, p. 57-59.
Zittel, K. A., von (1877): Studien uber fossile Spongien.
i. Hexa-actinellidae. Abh. K. Bayerische Akad.
Wiss.,Math. Phys. Kl., vol. 13, p. 1-63.
--(1878): Ditto, Zweiter Abthilung. Lithistidae.
Dritte Abteilung. Monactinellidae, Tetractinellidae
und Calcispongiae. Ibid., vol. 13, p. 65-154, pis.

1-12.

Fukuji m!tB, Ichinotani -(I):;:;:, Hida j\tW, Kitakami ~U:, Kobama I}~, Mizuboradani 7.KliOJ:;:;:, Mizuyagadani 7.K.§! tl:;:;: , Okatsu (Ogatsu) .~, Sakawa fteJli, Yakejima j\:ll{,IlI;.

j\twW!tB-(I):;:;:~.(I)~~Ae~1~~{t~: • • • ~.m~~Hm!tB(I)7.K.§!.:;:;:Kalli~~­(I):;:;:~~~$(I)~)jl(!fhH)liflj1:ff~~t.c ~ 1 ~ ~{t~;6~.lli~ ~o ~ (I);il~~Jt~Ii1fM~*~

fF JIX. L t::. ~<*,Cystauletes kingi, Amblysiphonella hidensis (I) 2 ~ fi ;6~ ~ ZU ~ h t::.
Cystauletes ~li19431f. King t;:: J: '? "{, 7 ~ !J ~it*l@* 9:7;1< "1"'I(I)*$~ ~ ~ /lo{.:. T*;6,0

I? mono typic -c'tJEP~ ~ht::. ~ (I)-e~ ~o A,@](I)~fili': (I)~(I) .lli¥IH!r'!:: L"( Ii i!tJi!. -C' 2 J.t §-e, l:~tj:\;;~(I) mammilosus J: fJ ~~,*t;::*~\,'*~~~,?o Amblysiphonella hidensislit't*9;oI?h"{\,,~~(I)J: fJ chamberil~~<, m;;6~~\',.:.!::-eIRZU~h~o~#JIIl~l!t - ~#JIIlMEl . :tcjl~TTrans. Proc. Palaeont. Soc. Japan, N.S., No. 150, pp. 465-475,4 Figs., June 30, 1988

858. A SPHENODISCID AMMONITE ACQUIRED RARELYFROM THE CRETACEOUS OF JAPAN*
TATSURO MATSUMOTO
c/o Department of Geology, Kyushu University 33, Fukuoka 812
and

YOSHIRO MOROZUMIDivision of Bunkanomori, Tokushima Prefectural Office, Tokushima 770

Abstract. This paper is the first record of a sphenodiscid ammonite from Japan. Whileammonite faunas from the Upper Campanian and Maastrichtian strata of Japan have recently
been under intensive investigation, Mr. Masahiko Takada fortunately found a sphenodiscidammonite from the Zone of Pachydiscus awajiensis in the Izumi Group of Awaji Island and has
kindly provided it through Mr. Masahiro Sato for our study. It is fairly large and characterized
by the mediolateral and ventrolateral nodes, low fastigiate to nearly tabulate venter of the
middle-aged whorl and a nearly smooth, adult body-chamber with the spirally extended
mediolateral zone of inflation, shallowly concave spiral zone outside the inflation and broadly
rounded venter. Although sutures are not well exposed, it represents a new species, which isallied to Libycoceras afikpoense Reyment but distinguished by its more numerous nodes andless acute venter of the phragmocone than those of that Reyment's species.
Morozumi's tentative correlation of the Zone of P. awajiensis to the upper Upper
Campanian is approved on the ground of this ammonite and restudied P. awajiensis itself.

the westerly contiguous hills of Awaji Island has
been proved to be of late Campanian to
Maastrichtian age on the evidence of ammonite
faunas (Matsumoto and Morozumi, 1980; Morozumi, 1985). It is one of the major stratigraphic
units from which a discovery of sphenodiscids could be expected, although ammonite
species recorded so far from the Izumi and
Awaji areas are mainly those of the Pachydiscidae,
Phylloceratidae, Tetragonitidae, Gaudryceratidae,
Nostoceratidae, Baculitidae and a rare species of
the Scaphitidae.
Meanwhile, Mr. Masahiko Takada fortunately
found an ammonite from Awaji which was
unfamiliar to him and provided it through Mr.
Masahiro Sato for our study. This is the firstrecord of a sphenodiscid ammonite from Japan.

Introduction
In spite of the fairly intensive investigations ofammonite faunas from the Upper Campanian and
Maastrichtian of Japan, no species of theSphenodiscidae has been described. This may be
due to the general scarcity of pseudoceratitic
ammonites in the Upper Cretaceous of Japan andmay be interesting from the viewpoint ofpalaeobiogeography or palaeoecology. For thebiostratigraphic purpose, however, it is desirable
to get members of the superfamilies Hoplitaceae
and Acanthocerataceae at successive stratigraphic
levels.
The Izumi Group of the Izumi Mountains and* Received March 15, 1988; accepted May 30, 1988.
465

Tatsuro MATSUMOTO and Yoshiro MOROZUMI

466

Although it is a single specimen, we describe it inthis paper to stimulate people for further
hunting.
Palaeontological descriptions
Family Sphenodiscidae Hyatt, 1900

Remarks:-Succeeding to Wright (1957, p.
L437), Howarth (1965) reviewed comprehensively the family Sphenodiscidae, giving diagnosisof the included genera and their geological ages.
More recently Zaborski (1982) has proposed thefamily Libycoceratidae for the two genera
Libycoceras Hyatt, 1900 and Indoceras Noetling,
1897. Zaborski says that the origin of these twogenera is different from that of Sphenodiscus
etc., although he does not indicate what it is.
Furthermore, he suggests, though with a query,that the origin of Sphenodiscus may lie either in
Lenticeratinae or in Placenticeras. In the lattercase the Sphenodiscidae should be transferred to
the Hoplitaceae. Anyhow, the Sphenodiscidae inthis paper is treated provisionally in a broad
sense as in Howarth (1965).

Awaji Island. This was in a calcareous nodule indark grey sandy siltstone; altered test is preserved
for the major parts, except for a peculiarly
damaged part on the right side. The specimen iscross-cut to two pieces in a natural state throughthe point close to the umbilicus. A cross-sectionof the inner whorls is visible obscurely on the
cutting plane.
Description :-The shell is fairly large. The
actually measured dimensions are shown in Table
1. The specimen is probably adult. The last
septum is at about d::::145 mm. The bodychamber can be assumed as long as 180·; thenthe entire shell diameter would be about 220

Genus Libycoceras Hyatt, 1900

Type species:-Sphenodiscus ismaelis Zittel, 1884.
Libycoceras awajiense sp. nov.
Figures 1,2

Holotype:-A specimen found by Masahiko
Takada from the Zone of Pachydiscus awajiensis
at loco Aw 7 (Nagata) of Morozumi (1985),mm.
The shell is discoidal and involute, with a very
narrow, almost closed umbilicus. The whorl ismuch higher than long, with its height increasing
at a moderate ratio. There is a spiral zone ofelevation at the level about the middle of flanksslightly closer to the umbilicus; that is the zoneof the maximum whorl-breadth. From this zone
the inner part of flank slopes down toward theumbilicus and the outer flanks converge toward
the venter.
In the observable part of the phragmocone
nodes are aligned on this elevated zone at wide
intervals, numbering 7 per half whorl. Also there
are nodes on the ventrolateral shoulder, normally
two ventrolateral nodes corresponding to one
mediolateral node. The venter is narrow, almost
tabulate or low fastigate, with a reduced keel on
the siphonal line. The venter of the next inner

Table 1.
Position

DiameterM
M-90·

180 (1)148 (1)

M-180·

Umbilicus

Height (H)Breadth (B)

B/H

H/h

109 (.61)
90 (.61)46 (.26)
39 (.26)

.42

1. 56

.43

70

32 (ic)35 (c).46.50

Height = Whorl-height; Breadth = Whorl-breadth; M = Measured position indicated in Fig. 1; h =whorl-height at
180· adapically from M; c = costal; ic =intercostal.
~ Figure 1.
Libycoceras awajiense sp. nov.
Holotype from loco Aw 7 (Nagata), Awaji Island (M. Takada Coll.). Left lateral (A), ventral (B) and frontal (C)views, x 0.8. Scale bar =20 mm. M: measured position, Arrow: position of the last septum.
Photos by courtesy of Dr. M. Noda.

858. Sphenodiscid Ammonite from Japan

467

468

Tatsuro MATSUMOTO and Yoshiro MOROZUMI

whorl is similarly low fastigiate and never soacute as to be called lanceolate. The ventrolateral
nodes are somewhat clavate, whereas themediolateral ones are subrounded but low. Bothnodes are rather blunt on the visible outer whorl
and disappear on the main part of thebody-chamber.
The low fastigiate shape of the venter is
obscured in the last part of the septate whorl
and the venter of the body-chamber isbroadly rounded, without angulation at theventrolateral shoulders. A very faint trace of the
reduced keel may be discernible along themedian line of the gently arched venter in somefavourable light, but speaking generally there isno keel on the venter of body-chamber. The
sRiral zone of elevation at about the middle offlank broadens and the body-chamber is gently
inflated there, whereas there appears a zone ofshallow depression outside the inflated zone.
The external surface of the body-chamber isnearly smooth and fine and dense lirae(growth-lines?) or striae are discernible where thepreservation is favourable. The lirae are gently
sigmoidal on the flank, shOWing a gentle
convexity on the middle part of flank and amoderate projection on the ventrolateral part,passing across the venter vertically. Similar radiallines or striae are also discernible on the surfaceof the phragmocone, whereas the ribs are
scarcely developed.
Comparison:-This specimen resembles ingross morphology and ornamentation the holotype and other examples of Libycoceras
afikpoense Reyment (1955, p. 89) (see also
Zaborski) (1982, p. 308), L. crossense Zaborski(1982, p. 309) and L. dandense (Howarth)(1965, p. 396 under Nenambolites) (seeZaborski, 1982, p. 313), from the Upper
Campanian of West Africa (Angola or Nigeria,
or both), but is not identical with any of them. It
is larger than the largest examples of them.
With respect to the shell-form with the
maximum breadth of whorl at the level of themediolateral tubercles, L. afikpoense is theclosest one among the three mentioned above tothe present species, but its mediolateral tubercles

are disposed at much wider intervals andaccordingly less numerous (4 per half whorl)
than those of our species. This is applied also to
the ventrolateral tubercles. Moreover, thesetubercles, particularly the ventrolateral ones, areprominent and persist well to the adult outerwhorl in that Nigerian species, whereas the
tubercles are blunt and disappear on the mainpart of the adult body-chamber in our species.
The existence of a spiral zone of shallow
depression outside the mediolateral zone ofgentle inflation on the body-chamber seems to be
characteristic of our species. According toZaborski (1982, p. 309), L. afikpoense shows
little variation. Therefore we regard the above
differences of our form to be sufficient for
specific separation.
Lewy (1977, p. 247) observed a certain extent
of variation in what he regarded as L. afikpoense
with respect to the stage at which the venter isflattening or broadening and also to the ratio ofthe distance between the mediolateral tubercle
and the umbilical seam and that between theventrolateral and the mediolateral tubercles.
Zaborski (1982) calls the forms from the Middle
East L. afikpoense-like. The specimens illustrated
by Lewy (1977, pI. 1, figs. 1-6 under L.
afikpoense and figs. 9-12 under L. ismaele) havemediolateral tubercles nearly as numerous as
those in our form but less numerous and much
more distant ventrolateral tubercles than those in
our form. There is, thus, a possibility thatsub specific distinctions could exist between
populations of separate provinces. This idea
should be examined on the basis of sufficientmaterial. At this moment we describe thespecimen from Awaji under a new specific name.
In L. crossense the tubercles are subdued andfinally disappear on the said adult whorl, which
is much smaller than that of ours. Also theinterspaces between the tubercles in that species
are as wide as those of L. afikpoense. The rib-likestructures extend inward from the tubercles in
the middle aged shell of L. crossense, but such
structures are scarcely seen in our form.
With respect to the low fastigiate venter in the
middle aged whorl and the broadly rounded858. Sphenodiscid Ammonite from Japan

469

Figure 2. Ubyco ceras awajiel1se sp. nov.
Righ t side of the ho iotyp e, showing an injur y and peculiar trace mark s, x 0.94.
Pho tos by courtesy of Dr. M. Noda.

venter in later whorl, L. crossense is similar to
our form, but its whorl is more compressed thanthat of ours.
The outer whorl of L. dandense has low ribson the outer flanks and ventrolateral clavi at theend of the ribs , but the mediolateral tubercles arelost or remain as slight elevations on the ribs.
This ornamentation is different from that of ourform. An example of L. dandense illustrated by
Zaborski (19 82, fig. 17) is fairly large, about 140

470

Tatsuro MATSUMOTO and Yoshiro MOROZUMI

mm in diameter at the end of the phragmocone,and may be nearly comparable in size with ourform, but the former is evidently more compressed than the latter.
The venter of our form in the middle aged
shell, with diameters from about 50 mm to 100
mm, is low fastigiate, but its summit is not so
acute as that of L. afikpoense or L. dandense at
the corresponding growth stages. In this respect
our form seems to approach to Indocerasbalchistanense Noetling (1897, p. 74), in which
the siphonal keel disappears at the diameter
about 70 mm in the middle-aged shell. That
species differs from ours in the absence of themediolateral tubercles and the presence of very
faint ribs on the outer flank in the major part ofthe phragmocone.
On the ground of the above comparisons, weare inclined to conclude that the specimen from
Awaji represents a new species of Libycoceras,
although a single specimen is available so far.
For more precise comparison and discussion,
the ontogenic change of every character should
be investigated. It is indeed too bad that we are
not successful to expose the full pattern of thesuture. However, we dare to describe it as a new
species for the moment to stimulate people tohunt for additional, more favourably preserved
specimens.
Occurrence:-Loc. Aw 7 (Nagata) of Morozumi (1985), exactly 1.5 km east of Nagata,
Midori-cho, Mihara-gun, Hyogo Prefecture. The
specimen occurs in fine-sandy siltstone of the
Seidan Forma tion.
National Highway No. 28 was under construction in the year 1985-1987, passing through'Figure 3. Map showing the details around the fossiliocality, marked by x, Inset is the index map of Awaji(Y. Morozumi delin.)
Island, with dotted pattern outlining the distributional area of Cretaceous strata.

858. Sphenodiscid Ammonite from JapanAw 7. The outcrop of Aw 7 was enlarged
and numerous (more than 100) fossil specimens
were collected there (Fig. 3). The great majorityof them belongs to Pachydiscus awajiensis
Morozumi and the rest consists of a single
sphenodiscid ammonite described above, an
example of Neophylloceras aff. mikobokense(Collignon) (see Morozumi, 1985), several
specimens of Baculites inornatus Meek (Obata
and Matsumoto, 1963), "Anisomyon" problematicus (Nagao et Otatume) and Yaadia
obsoleta (Kobayashi et Amano). This fossiliferous exposure is the stratotype of the Zone of
Pachydiscus awajiensis proposed by Morozumi(1985, p. 13). It is stratigraphically about 200 m
above the base of the Izumi Group in this area.

Biostratigraphic correlation
On account of the palaeogeographic separation, marine faunas of the Campanian and
Maastrichtian ages in the Japanese province areconsiderably different from those in West Europe
where stratotypes of the stages exist. Species
which are common between the two provinces
are very few. For this reason it is difficult todraw precisely the Campanian-Maastrichtianboundary in the stratigraphic sections in theJapanese province.
The late Cretaceous Izumi Group, which
extends from east to west for about 300 km in
Southwest Japan, consists of thick piles of theturbidite facies for the major part (see Tanaka,1965). There is, however, in the basal part of thegroup, a unit of muddy sediments which containfossiliferous nodules. It probably represents a
neritic shelf facies. This unit is diachronous,
becoming gradually younger from west to east, as
evidenced by the tracing of key tuff beds or
tuffite in geological mapping (e.g., Suyari, 1973)
and also by guide species occurring in several
places (see Matsumoto, 1980; Morozumi, 1985,
figs. 12, 13).
At a locality (numbered here 1) in the city ofMatsuyama near the western end of theoutcropping belt of the basal unit of the Izumi
Group, Sphenoceramus schmidti (Michael), S.

471

sachalinensis (Sokolow), Gaudryceras striatum(Jimbo) etc. form a characteristic assemblage. In
the coastal area (2) facing the Seto Inland Sea,
about 40 km to the east from Matsuyama,
Bevahites aff. B. lapparenti Collignon (Matsumoto and Obata, 1963) and Delawarella sp.
(Inami and Ochi, 1986) were obtained together
with Inoceramus (Endocostea) sp. These species
from the two places (1, 2) in the northwesternpart (Ehime Prefecture) of Shikoku indicate theupper part of the Lower Campanian in a
bipartite scheme.
At several localities (3), about 70 to 80 km
east of (2) in the Sanuki (or Asan by somepeople) Mountains, northeastern part (Kagawa
Prefecture) of Shikoku, Metaplacenticeras subtilistriatum (Jimbo) occurs characteristically(Bando and Hashimoto, 1984). This species is
associated with Hoplitoplacenticeras monju Matsumoto, H. fugen Matsumoto and many otherammonites in the type locality and adjacent areaof northern Hokkaido, indicating the lower
Upper Campanian (Matsumoto and Miyauchi,1984). The ammonite faunule from the basal
siltstone in the eastern part (4) of the Sanuki
Mountains, easterly contiguous to (3), has yet tobe worked out, for only Baculites kotanii wasdescribed clearly (Matsumoto et al., 1980)
among others, which occur at several levels
higher than the Zone of M. subtilistriatum.
Further to the east in the Island of Awaji,
Morozumi (1985, p. 4-13, especially tables 1,2
and figs. 1-3) has shown that the siltstone in thebasal unit (which he called the Seidan Formation) becomes younger eastwards and distinguished the following zones in the Awaji
section of the Izumi Group in ascending order(with numbered type locality in parentheses):
Zone of Didymoceras awajiense (5, Anaga)
Zone of Pravitoceras sigmoidale (6, Minato)
Zone of Pachydiscus awajiensis (7, Nagata)
Zone of Nostoceras hetonaiense (8, Mitsugawa)
Zone of Pachydiscus aff. subcompressus (9,Yamamoto)(Numbers follow those in Shikoku as
explained above. See Fig. 4).

"""
tv

-...l

I noceramids
x-Inoceramus shikotanensist - Sphenoceramus schmidti
Ammonites
v- Pachydiscus aft. flexuosus~- Pachydiscus att. subcompressus
A- Nostoceras hetonaiensec- Pachydiscus awajiensis• - Pravitoceras sigmoidal eo-Didymoceras awajiense. - Didymoceras sp.
IA-Baculites kotanii+- Metaplacenticeras
subtil istriatumN~+:c:!;J~~
':0

~

~
Cl

~
~

~

..

0

o 1:1

C3
I::>

."

;::s
I::>...

3,oN-l

~

">

~

a-

~

SHIKOKU

:..:,
0
N

~
.....

I>

PACIFIC OCEANoI

Figure 4.

50km
I

Map showing selected fossil localities of the Izumi Group with zonal indices. Dotted area indicates the distribution of the Izumi Group. M. T.
(Adopted from Morozumi, 1985, fig. 12)

L.: Median Tectonic Line.

858. Sphenodiscid Ammonite from Japan
In addition to the domestic correlation,
Morozumi (1985, p. 46-53) tentatively attempted at international correlation, with thelower three zones (5, 6, 7) being correlated to
the Upper Campanian and the upper two (8,9)
to the Maastrichtian. To draw the stage boundary
between the Zone of Pachydiscus awajiensis andthe Zone of Nostoceras hetonaiense is quite
tentative as the author himself repeatedly
remarked.
It should be noted that P. awajiensis
Morozumi, 1985 is fairly similar to P. koeneni deGrossouvre, 1894, which occurs commonly inGermany, Switzerland, Austria, Poland, Donbas,
Kopet Dag etc. In the former, represented by theholotype (Morozumi, 1985, text-fig. 4 and pI. 2,
fig. 1) and the paratype (Ditto, pI. 2, fig. 2), theribs are narrow and separated by broader
interspaces, the longer ribs are gently flexuous,
showing a concave curve at about the umbilicalshoulder and another concavity on the outerflank. Such a biconcave flexuosity may occasionally appear on some of the longer ribs in thelatter species but normally the long ribs arealmost rectiradiate on the inner flank, startingfrom the umbilical bullae, as seen in thelectotype designated by Kennedy and Summesberger (1984, pI. 14, fig. 2 = Ammonites
galicianus of Schluter, 1872, pI. 19, fig. 3) andmany other examples (e.g. illustrated by Moberg,
1885 under Amm. oldhami; Blaszkiewicz, 1980;
Kennedy and Summesberger, 1984). Also theribs look somewhat coarser and are separated bynarrower interspaces in P. koeneni than in P.
awajiensis, but this may be due to the state ofpreservation in that many examples from Europe
are internal moulds, whereas the shell ispreserved in the specimens from Awaji.
The above mentioned differences seem tooccur constantly but are by no means great.
Therefore, someone may consider P. awajiensis asa geographical subspecies of P. koeneni of the
Boreal region.
Incidentally, Kennedy and Summesberger(1984, p. 158) regarded P. koeneni as macroconchs and the bituberculate Amm. heldemsis
Schluter, 1867 (p. 19, pI. 3, fig. 1) as

473

rnicroconchs of one and the same species. They
are so confident that they put P. koeneni deGrossouvre, 1894 as a junior synonym of P.
haldemsis (Schluter, 1867). This could be so, but
may give a difficulty. From the Zone of P.
awajiensis no example of the small, bituberculate
counterpart has been obtained. Without getting
an adequate microconch, we hesitate to state
either that P. awajiensis is closely allied to P.
haldemsis or that it may be a subspecies of P.
haldemsis. Apart from the nomenclatorial difficulty, the close resemblance between P. awajiensis and P. koeneni would support the tentative
conclusion of Morozumi (1985) to refer theZone of P. awajiensis to the Upper Campanianinstead of the Lower Maastrichtian.
The sphenodiscid ammonite obtained fromthe type locality of P. awajiensis is a new species
and cannot work as a direct indicator of age. Itis, however, allied to Libycoceras afikpoense, as
we have described above. That species occurs
abundantly in the basal part of the Nkporo Shaleof Nigeria. Reyment (1955) ascribed the age ofthis formation to the Maastrichtian, but now
Zaborski (1982, 1985) has shown with sufficientevidence that the lower part of the Nkporo
Shale, which contains L. afikpoense, Sphenodiscus lobatus lobatus (Tuomey, 1856) (seeZaborski, 1982, p. 316) and certain otherammonites, is referred to the Upper Campanian(Zaborski, 1982, fig. 36; 1985, p. 61). Therefore,
we can state that Libycoceras awajiense approves
in~irectly Morozumi's assignment of the Zone of
Pachydiscus awajiensis to the upper Upper
Campanian.
Acknowledgments
We wish to thank Messrs Masahiro Sato and
Masahiko Takada for their generosities inproviding the valuable specimen for this study.
We very much appreciate Mr. Takada's keen sightin hunting this rare ammonite. Thanks areextended to Mr. P. M. P. Zaborski for hiskindness in giving to one of us (T. M.)
unpublished information, to Dr. Ikuwo Obata forstimulating discussion, to Dr. Masayuki Noda for474

Tatsuro MATSUMOTO and Yoshiro MOROZUMI

his friendly help in taking photographs, and toMiss Yoshirni Tanigawa for her assistance inpreparing the typescript. We are much obliged to
two anonymous referees for improving themanuscript.
References cited
Bando, Y. and Hashimoto, H. (1984): Biostratigraphy
and ammonite fauna of the Izumi Group (Late
Cretaceous) in the Asan Mountains. Mem Fac.
Educ., Kagawa Univ., Ser. 2, vol. 34, no. 1, p.
11-39 (in Japanese with Engl. abstract).
Blaszkiewicz, A. (1980): Campanian and Maastrichtianammonites of the middle Vistula river valley,
Poland: A stratigraphic-paleontological study.
Prace Instytutu Geologicznego, no. 92, p. 1-63,
pis. I-56, Warszawa.
Grossouvre, A. de (1894): Recherches sur la Craie
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Howarth, M. K. (1965): Cretaceous ammonites andnautiloids from Angola. Bull. Brit. Mus. (Nat.
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Hyatt, A. (1900): Cephalopoda. In Zittel, K.A.-Eastman, C. R.: Textbook of Paloeontology, 1st Engl.
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159-161 (in Japanese).
Kennedy, W. J. and Summesberger, H. (1984): Upper
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Korea, vol. 10, no. 4, p. 239-244.
- - , Furuichi, M. and Hashimoto, H. (1980): An
interesting species of Baculites (Ammonoidea)from the Cretaceous Izumi Group of Shikoku.
Proc. Japan A cad. , vol. 56, Ser. B, p. 408-413.
--and Miyauchi, T. (1984): Some ammonites fromthe Campanian (Upper Cretaceous) of northern
Hokkaido. Palaeont. Soc. Japan, Spec. Pap., no.
27,93 pp., 31 pis.
--and Morozumi, Y. (1980): Late Cretaceousammonites from the Izumi Mountains, Southwest

Japan. Bull. Osaka Mus. Nat. Hist., no. 33, p.
1-31, pis. 1-16.
--and Obata, I. (1963): Bevahites (Cretaceousammonite) from Shikoku. Bull. Natn. Sci Mus.,
Tokyo, vol. 6, no. 4, p. 405-410, pI. 6.
Moberg, J. C. (1885): Cephalopoderna Sveriges
Kritsystem. II. Artbeskrifning. Sver. Geol. Unders.,
Ser. C, no. 73, p. 1-64, pis. 1-6.
Morozumi, Y. (1985): Late Cretaceous (Campanian and
Maastrichtian) ammonites from Awaji Island,Southwest Japan. Bull Osaka Mus. Nat. Hist., no.
39, p. 1-58, pis. 1-18.
Noetling, F. (1897): Fauna of the Upper Cretaceous(Maastrichtian) beds of the Mari Hills. Mem Geol.
Surv. India, Palaeont. Indica, Ser. 16 (Fauna of theBalchistan), vol. 1, pt. 3, p. 1-79, pis. 1-23.
Obata, I. and Matsumoto, T. (1963): A monograph of
the Baculitidae from Japan. Part II. Somebaculitids from Honshu. Mem. Fac. Sci. Kyushu
Univ. Ser. D, vol. 13, no. 1, p. 75-92, pis. 22-27.
Reyment, R. A. (1955): The Cretaceous Ammonoidea
of southern Nigeria and the southern Cameroon.
Geol. Surv. Nigeria, Bull no. 25, p. 1-112, pis.
1-25.
Schliiter, C. (1867): Beitrag zur Kenntnis der jungsten
Ammoneen Norddeutschlands, 36 pp., 6 pis., A.
Henry, Bonn.
--(1871-1872): Cephalopod en der oberen deutschen Kreide. I. Theil. Palaeontographica, vol. 21,
p. 1-120, pis. 1-35.
Suyari, K. (1973): On the lithofacies and correlation of
the Izumi Group of the Asan mountain range,
Shikoku. Sci Rept., Tohoku Univ., 2nd Ser.
(Geol.), Spec. Vol. no. 6, p. 489-495 (in Japanesewith Engl. abstract).
Tanaka, K. (1965): Izumi Group in the central part of
the Izumi Mountain Range, Southwest Japan, withspecial reference to its sedimentary facies andcyclic sedimentation. Geol. Surv. Japan, Report,
no. 212, 34 pp., 8 pis.
Tuomey, M. (1856): Description of some new fossils
from the Cretaceous rocks of the southern states.
Proc. Acad. Nat. Sci., Philad., vol. 7, p. 162-172.
Wright, C. W. (1957): In Moore, R. C. (ed.) Treatise on
Invertebrate Paleontology, Part L, Mollusca 4,
Cephalopoda, Ammonoidea. xxii + 490 pp. Geol.
Soc. Amer. & Univ. Kansas Press, New York &Lawrence.
Zaborski, P. M. P. (1982): Campanian and Maastrichtian
sphenodiscid ammonites from southern Nigeria.
Bull Brit. Mus. (Nat. Hist.), Geol., vol. 36, no. 4,
p.303-332.
--(1985): Upper Cretaceous ammonites from theCalabar region, south-east Nigeria. Ibid., vol. 39,
no. 1, p. 1-72.

858. Sphenodiscid Ammonite from Japan

475

Asan lI"Jiii, Awaji ~Nt, Ehime ~~, Hokkaido ~trt!i~, Hyogo ~ 1$, Izumi '¥!l*,Kagawa 1!f

JII, Matsuyama f~l1l, Midori-cho ~PIJ, Mihara-gun =:J.ij(!B, Nagata :/jtffi, Sanuki iiillit, Seidan
l1§ ~, Seto ifip.

B*0) t::L!II!*i.P l?1ifflt~f4l?ht-:7- 7 ;r. / T' -{ 7- P' f47 /'.!£:-:;t-1 r : *fi30) 8.!11!*0)J\lJ:$i kli/'.!£:-:;t-1 r ~;6';P-C;6' I?~* L -C \, ,t-:. ::::. 0) vi C
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afikpoense ReymenO;:M{J;.l-t ~ tJ~, ~~-Cli~~tJ~ t "? tJA\',ra,~'(·~tJ..'tJ:\"tJ~:/jt f?~ L, it-:XiJ~9='1pW1O)7i-iIiitJ~~ <'!R "? -C \,,~ • .:to)ftl!0)~ t t~tJ: ~ O)'('~~ L. awajiense t -t~.

<::::'o)~*li'¥!l*~ml1§~~O)Pachydiscus awajiensis~~;:i£ Lt-:. 1i'iJ~li:fJ /',{.:=. 7 /' . ~ 7-r 1) ~ 7- 7 /'O)m~;:jIT <, Morozumi (1985) li!TtEl¥J~;::fJ /'.I{,:=, 7 /'J\lJ:$~;:%j.lt L t-:. L~li
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koeneni de Giossouvre ~~jIT{J;.l'('1>~. ::::'hI?O)$~li~ ~O)mtiltfU~3Z:~-t~ t \,,;t~.
~1ltJ:$~;: i -Cf?~-t ~;6~, L. afikpoenseli:fJ /' ,{.:=. 7 /' J:$~;:i£ L,

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Trans. Proc. Palaeont. Soc. Japan, N.S., No. 150, pp. 476-490, 7 Figs., June 30, 1988

859. FUNCTIONAL AND TAXONOMIC IMPLICATIONSOF INTERNAL RIBS OF PROPEAMUSSIUM*

ITARU HAYAMI
Geological Institute, University of Tokyo, Tokyo 113

Abstract. The macroscopic and microscopic features of internal ribs in several living andfossil pectinaceans from the western Pacific were observed, and their functional and taxonomic
significances were considered. Propeamussium shares internal ribs with Amusium and someother genera of the Pectinidae, but the resemblance must be superficial because theirfundamental structure is quite different. The commonly paired internal ribs of pectinids areformed by the thick secretion of outer foliated layer near the ventral margin and primarily serve
the tight interlocking of valve margins. On the other hand, each of the internal ribs ofpropeamussiids is represented by a lecticular core of fibrous prismatic (or foliated) calcite
almost imbedded in the inner layer of crossed lamellar aragonite. Genetically, the cores seemto have originated from the "middle layer" (a thin layer beneath the prismatic layer) in theright valve and from the outer layer in the left valve and to be produced by some patchy
isolation of shell-secreting mantle tissue. The distal ends of internal ribs are just apposed tothose of the counter valve so as to contact each other when the valves are tightly closed. Theinternal ribs of propeamussiids may be functionally analogous to the auricular crura offree-living pectinids; the distal ends probably serve as buttresses to counteract not only
external compressive stresss but also powerful contracting force of quick adductor muscle forswimming.

Introduction

characters and is rather similar to the Pernopectinidae from the Upper Paleozoic (Waller
1972, 1978; Newell and Boyd 1985). A distinct
family, Propeamussiidae Abbott, 1954, wasredefined and became widely accepted, whereas
Amusium remained in the Pectinidae because theshell microstructure and anatomical features are
typical of the family. Both the Pectinidae and
the Propeamussiidae mayor may not possessinternal ribs, and therefore homologous relationship of internal ribs between the two families
may be strongly doubted.
During the course of my extensive survey ofthe shell morphology and microstructure ofJapanese deep-sea pectinaceans, it was noticed
that the arrangement, developmental origin andfunction of internal ribs are considerably
different between the Pectinidae and thePrevious suprageneric classification of postPaleozoic pectinaceans seems to have attached
too much importance to the presence or absenceof internal ribs without considering theirdevelopmental background. Propeamussium andsome other related deep-sea genera, whichapparently share internal ribs with Amusium,
were commonly referred to the Amusiinae(Thiele 1935, Orlov 1960, etc.) or to theAmusium group of the Pectinidae (Hertlein in
Cox et al. 1969, Vokes 1980). Since Waller(1971) pointed out the primitive shell features ofPropeamussium, however, it has been recognizedthat this genus is fundamentally different from
Amusium and other pectinids in many essential*Received April 9, 1988; accepted May 30, 1988.
476

859. Internal ribs of Propeamussium
Propeamussiidae. This paper is mainly concernedwith functional and taxonomic evaluations of
this character on the basis of several CenozoicRecent species of the two families.
Internal ribs of the Pectinidae
In the Pectinidae conspicuous internal ribs
occur not only in Amusium but also in a numberof warm-water genera (e.g. Pecten, Aequipecten,
Annachlamys, Equichlamys and Amussiopecten).
In many cases the internal ribs are regularly
paired and occur along the margins of eachinternal elevation corresponding with an interval
between two external radial costae. As recognized well in articulated specimens of Pecten(especially in the full-grown stage), the outersides of the paired internal ribs are in contact
with those of the counter valve near the ventral
margin so as to ensure the tight interlocking of
disk margins (Fig. I-Sa).
The internal ribs of Amusium are notnecessarily stronger than those of Equichlamys
and A mussiopec ten, but have been noticed byprevious taxonomists because the externalsurface is nearly smooth. Contrary to expectation, their arrangement is discrepant between theright valve (RV) and the left valve (LV). In every
articulated specimen of Amusium japonicum andAmusium pleuronectes, so far examined, RV(yellowish valve) has more numerous and moreregularly paired internal ribs than LV (reddish
valve) of the same individual (Fig. 1-4a). Theinternal ribs must reinforce the relatively thinvalves to a certain extent, but it is unknown
whether this structure bears other functional
meaning or represents only a vestigial structure.
From the geographic and stratigraphic distributions I presume that Amusium was phylogenetically derived from Amussiopecten-like weakly
costate warm-water species (not from Lentipecten as considered by some previous authors),
and that the paired regularity of internal ribs aswell as the interlocking function was almost lostin accordance with the disappearance of radial
costae. The thin shells and smooth externalsurface of Amusium are no doubt advantageous477

for swimming habit, because they can minimize
the gravity and drag force.
In Amusium and some other free living
pectinids auricular crura, which are the distallyextended loci of auricular denticles, are welldeveloped (Figs. 1-4b, 5b). As was interpreted byWaller (1969), they are apposed rather thaninterlocking and seem to serve as buttresses
against compressive stresses, because the anterodorsal and postero-dorsal disk margins of suchpectinids are widely open even in tightly closed
condition. The internal ribs of the Pectinidae arealways formed by the thickening of outer
foliated calcite layer near the ventral margin andthen covered by the inner layer of crossed
lamellar aragonite. The auricular crura areprobably of different origin from the internal
ribs, because they are produced by the thicksecretion of the inner layer.
Shell structure of the Propeamussiidae
Although it is not the principal aim of thispaper to describe the shell microstructure,
appropriate knowledge of the characteristic
layering of propeamussiid valves seems to beindispensable for the consideration of thefunctional and evolutionary significances ofinternal ribs. Here, previous studies on thismatter are briefly reviewed, and some results of
my SEM observations are presented. About theterminology I follow Carter and Clark II (1985)
who presented a comprehensive classification
scheme of molluscan shell microstructure.
Previous studies. In spite of many outstanding
comprehensive studies on the shell microstructure of bivalves (e.g. Bf1lggild 1930, Taylor,
Kennedy and Hall 1969, 1971), the peculiarfeatures of Propeamussium had been unnoticed
until Waller (1971) pointed out its primitivenessand similarity to some Paleozoic pectinoids. As
successively studied by Waller (1972, 1978,
1984), the extant species of Propeamussium areclearly distinguishable from the Pectinidae bymany important characteristics. Among others,
the development of a simple prismatic calcite
layer on the greater part of the external surface

478

Itarn HA YAMI

859. Internal ribs ofPropeamussiumof RV until the latest growth stage, thedistribution of inner layer (crossed lamellar
aragonite) on the internal surface beyond thepallial myostracum, and the absence of true
ctenolium even in the early growth stage areenough to be regarded as family-level diagnostic
characters (Fig. 3).
In living specimens of Propeamussium, aspreviously noticed by Kuroda (1931), the ventral
area of RV, called flexible prismatic apron by
Newell and Boyd (1985) and marginal apron
here, easily becomes concave when the valves areclosed. The flexibility is of course due to thestructure of this area consisting of a single layerof simple prismatic calcite (Fig. 4). Discrepant
shell microstructure between RV and LV in someliving and fossil species of Propeamussium was,independently of Waller's works, pointed out by
Okubo and Inoue (1975), who showed some
SEM photographs of the natural, fracture andsectional surface for the first time. More recently
Newell and Boyd (1985) also observed someliving species of Propeamussium and compared
the microstructure with that of Pernopecten andother Late Paleozoic pectinoid genera.
The descriptions of shell microstructure bythese authors are not necessarily coincident with
one another. For example, the outer layer of LV
and the "middle layer" (a thin layer beneath theprismatic outer layer) of RV were described byWaller (1972) as composed of foliated calcite but~

479

assigned by Newell and Boyd (1985) to fibrousprismatic structure. The apparent discrepancy, I
think, may have arisen from the variable crystal
elongation of calcite laths among species (orobserved portions). Carter and Clark II (1985)
described the outer layer of LV of Propeamussium dalli as lath-type fibrous prismatic but
noted that regularly foliated structure (Gamma
135 blades) also occur in this species. Okubo andInoue (1975) considered that the outer foliatedlayer of LV of "Luteamussium sibogae" [=Propeamussium sibogai] is thinly covered with aporcellaneous layer and that there is a thinfibrous layer on the internal surface of both
valves. I presume that these thin surface layers
are not of original structure but products ofweathering, because their material was said to bedead shells.
Results of observations. I have carried out,
though still preliminarily, SEM observations ofshell microstructure on the basis of the following
nine propeamussiids:
Propeamussium caducum (Smith, 1885)
Propeamussium cmadoritinctum (Kuroda, 1931) [Figs.
2-1,2]

Propeamussium je!!reysi (Smith, 1885) [Fig. 2-3]
Propeamussium sibogai (Dautzenberg and Bavay, 1904)[Fig. 2-4]

Propeamussium watsoni (Smith, 1885) [Figs. 2-5,6]
Polynemamussium alaskense (Dall, 1872) [Fig. 1-3]
Polynemamussium intuscostatum (Yokoyama, 1920)[Figs. 1-1,2]

Figure 1.

Polynemamussium intuscostatum (Yokoyama, 1920)
1. Articulated valves (UMUT RM18274) x 4, from Sagami Bay (off Jogashima islet, 100m). la: RV withincomplete marginal apron, 1b: LV.
2. Articulated valves (UMUT RM18275) x 4, from the same locality. 2a: interior of RV without marginal apron,
2b: LV.
Polynemamussium alaskense (Dall, 1872)
3. Articulated valves (UMUT RM18276) x 1.5, from Japan Sea (off Otaru City of Hokkaido, 150m). 3a: RV
without marginal apron, 3b: interior of the same valve, 3c: LV, 3d: interior of the same valve.
Amusiumjaponicum (Gmelin, 1791)
4. Young articulated valves (UMUT RM18277) x 1.2, from Hyuga-nada (off Touriyama of east Kyushu). 4a:
discrepant internal ribs between RV (upper) and LV (lower), 4b: hinge areas showing apposed auricularcrura.
Pecten albicans (Schrater, 1802)
S_ Full-grown articulated valves (UMUT RM18278) x 0.8, from Tosa Bay (off Kochi City of Shikoku). Sa:interlocking internal ribs between RV (upper) and LV (lower), 5b: hinge areas showing apposed auricularcrura.

480[taru HA YAMI

859. Internal ribs of Propeamussium
Cyclopecten bistriatus (Oall, 1916)
Cyclopecten nakaiiOkutani, 1962 [Figs. 2-7,8)

Besides, the shell structure of Delectopecten
species was examined, because this deep-water
genus is also characterized by thin translucent
shells and was regarded by some Japanese
authors (e.g. Oyama 1944, Habe 1977) as related
to Propeamussium and Cyclopecten.
All of these examined species of Propeamussium, Polynemamussium and Cyclopecten
share the diagnostic characters of the Propeamussiidae defined by Waller (1972, 1978). On
the contrary, Delectopecten obviously belongs to
the Pectinidae, because of the presence of true
ctenolium and because the outer layer of RV and
LV are similarly composed of regularly foliatedcalcite except for the narrowly distributed simple
prismatic layer on the earliest dissoconch of RV[SEM photographs were already shown by
Hayami and Okamoto (1986)]. According to
Runnegar's (1984) crystallographic study offoliated calcite, the calcite laths of the outerlayer of Delectopecten are referable· to arhombohedral form (1012) [or Gamma 135
blades of Carter and Clark II (1985)].
The shell microstructures of these nine extant
propeamussiids are essentially similar, but there
are some minor variations. The crystal habit ofcalcite laths in the outer layer of LV and the"middle layer" of RV varies considerably not
only among species but also within the samelayer of an individual. In Propeamussium
watsoni, for example, the inner part of the outerlayer of LV reveals lath-type fibrous prismatic
structure (Fig. 5-3A), whereas its outer part isclearly composed of regularly foliated calcite(Gamma 135 blades) (Fig. 5-3B). Though
crystallographic relation between fibrous prismatic calcite and foliated calcite should befurther studied, the apparent difference between
the two microstructures, at least in this case, ismerely attributable to the variation in theelongation of laths. Lath-type fibrous prismatic
calcite often seems to change by gradation into
foliated calcite also in other species of thePropeamussium The growth direction of laths isinvariably almost radial (more precisely, orthogonal to growth increments) in fibrous prismatic
shell but often much fluctuated in foliated shell.
In Polynemamussium and Cyclopecten the outerlayer of LV and the "middle layer" of R V are
almost invariably composed of regularly foliatedcalcite.
In most propeamussiids the shell microstructure is similar between the outer layer of LV
and the "middle layer" of RV. Propeamussium
jeffreysi, however, represents an exception, in
which the outer layer of LV, unlike the regularly
foliated (or prismatic fibrous) "middle layer" of+- Figure 2.
Propeamussium cmadoritinctum (Kuroda, 1931)

481

. ,
1. Right valve without marginal apron (UMUT CM18279) x 2, from the Upper PleIstocene Wan FormatIOn at
the north of Kamikatetsu, Kikai Island. 1a: exterior, 1b: interior.
2. Left valve (UMUT CM18280) x 2, from the same locality. 2a: exterior, 2b: interior.
Propeamussium jeffreysi (Smith, 1885)
3. Articulated valves (UMUT RM18281) x 1.5, from Enshu-nada (ca. 300m). 3a: RV with incomplete marginal
apron, 3b: interior of the same valve, 3c: LV, 3d: interior of the same valve.
Propeamussium sibogai (Oautzenberg and Bavay, 1904)
4. Articulated valves '(UMUT RM18282) x 1.5, from Kumanonada (off Owase City of Kii Peninsula, 150m). 4a:
RV with incomplete marginal apron, 4b: interior of the same valve, 4c: LV, 4d: interior of the same valve.
Propeamussium watsoni (Smith, 1885).
5. Living specimen with injured-and-repaired valves (UMUT RM18283) x 1.5, from Hyuga Sea BaSin (KT-86-16,
St.02, 1650m). Left view.
6. Articulated valves (UMUT RM18284) x 1.2, from the same locality, 6a: interior of RV, 6b: interior of LV.
Cyclopecten nakaii Okutani, 1962
7. Living specimen (UMUT RM18285) x 2, from Izu Sea (KT-87-19, St.TW7, 1182-1215m). 7a: right view, 7b:
left view.
8. Articulated valves (UMUT RM18286) x 2, from the same locality. 8a: interior of RV, 8b: interior of LV.

ftaru HA YAMI

482

RV (Fig. 5-5A), reveals semifoliated microstructure in Carter and Clark II's (1985)
classification (Fig. 5-6).
In the Propeamussiidae the greater part of thedisk of RV is invariably covered with a prismatic
outer layer. Radial and other conspicuous
external sculptures never appear on the surfaceof this microstructure (Waller 1972). The prisms
are commonly polygonal and nearly perpendicular (or only slightly oblique) to the surface(Figs. 5-1,2B,4), but fine commarginal costellaeon the external surface of RV, if present, areconstructed by commarginal rows of radially[orthogonally] elongated prisms, as were described by Carter and Clark II (1985) in
Propeamussium dalli Therefore, the prismatic
layer is often represented by a zonal alternationof simple prisms and orthogonally elongatedprisms. In some species of Propeamussium andCyclopeeten faint intermittent orthogonal striae

are observed on the top of commarginal costellaeof RV. The orientation of the intermittent striae
is apparently similar to that of the "Camptoneetes striae" of the Pectinidae, but the
crystallographic background must be different(see also Hayami and Okamoto, 1986).
Waller (1976) mentioned, though briefly, thatfoliation actually occurs within the simple prisms
themselves in RV of the Propeamussiidae andsome other pteriomorph families. On this groundhe regarded the foliated structure in advanced
pteriomorphs as having evolved from simple
prismatic structure. Such foliated simple prisms
are clearly observable on the internal surface of
RV (only near the ventral periphery of marginal
apron) in Propeamussium watsoni and Cyclopee ten nakaii, and can be expected in otherspecies of this family as well (Fig. 5-2A).
However, the foliation in the prisms isundoubtedly of Gamma 120 blades, which

Left valve

Right valve

10mm

m
•

prismatic calcite

prismatic aragonite

ft:::rrrrN fibrous prismatic (or foliated) calciteDcrossed iamellar aragonite

Figure 3. Internal shell features of Propeamussium sibogai, drawn on the basis of an articulated
specimen (UMUT RM18282). RV looks somewhat smaller than LV, because of the incomplete marginal
apron. [adapted from Hayami 1988]

859. Internal ribs ofPropeamussium

Right valve

Left valve483

suggest the origin of foliated structure.

Taphonomic evaluation of marginal apron.

~

prismatic calcite

I?~{:::I

fibrous prismatic (or foliated) calciteDcrossed lamellar aragonite

Figure 4.

Some taxonomists (especially paleontologists)
regarded the relative length of internal ribs andsize discrepancy between the two valves as useful
criteria for subdivision of the Propeamussiidae.
Parvamussium, for instance, was often discrimi·
nated from Propeamussium by the distal ends ofinternal ribs approaching the "valve margin".
Many species of this family were described as"RV smaller than LV", or "internal ribs reaching
the valve margin in RV but not in LV". Suchdescriptions, as pOinted out by Newell and Boyd(1985), seem to have arisen from observations ofincomplete specimens.
I have collected many living specimens ofPropeamussium, Polynemamussium and Cyclopecten from the Japanese deep·waters by
dredging and trawling, but size discrepancy
between RV and LV has not been observed inany species. When the valves are closed, themarginal apron of RV, which is invariably
composed of a single layer of prismatic calcite, isalways reflex along the internal surface of LV(Fig. 4). The marginal apron is enough flexible inwet condition owing to the conchiolin filling theinterspace of prisms, but, if dried, it becomesvery fragile and is apt to be broken into pieces.
Since the marginal apron of RV is rarely
preserved in fossils (e.g. Figs. 2·la,b) and dried
museum specimens, taxonomists must be careful.

Schematic vertical section of Prope·amussium (along the top of an internal rib). When thevalves are closed, the marginal apron of RV becomes
concave, and the distal end of each internal rib is incontact with that of the counter valve. The convexity
and thickness of valves are much exaggerated. OL: outerlayer, ML: "middle layer", IL: inner layer, PM: pallial
myostracum, CR: core of internal rib, MA: marginal
apron, QM: quick adductor muscle.

represent the basal pinacoid (0001) of calcite(see Runnegar 1984). Therefore, the foliation in
the outer prismatic layer of RV is crystallographically different from that of other layers. I
presume that foliated structure is easily derived
from lath· type fibrous prismatic structure, but it
is doubtful whether such foliated prisms directlyInternal ribs of the Propeamussiidae

Structure of internal ribs. Internal ribs occur
in many species of the Propeamussiidae, though
undeveloped in Cyclopecten (Figs. 2.8a,b) andyoung valves of Polynemamussium (Figs. 1·2a,b,3b,d). Unlike the Pectinidae, they are neverpaired and have no relation to the external
SCUlpturing. For example, if a left valve of
Propeamussium jeffreysi is seen through, it isreadily recognized that the internal ribs slightly
curve outwards and are often more or lessoblique to the external radial costae in LV (Figs.
2·3c,d).
As diagrammatically shown by Waller (1972),

484

ftaru H A YAMI

859. Internal ribs of Propeamussium

485

Structure of internal ribs (right valve)

_- IL

-CR
-- IL

~~~~--- ML
---OL

'CMR

Figure 6. Block diagram showing the structure of internal ribs in RVof
Propeamussium. The lenticular core of internal rib is sometimes not completely
separated from the "middle layer". The interval of internal ribs is not to scale.
OL: outer layer of prismatic calcite, ML: "middle layer" of fibrous prismatic (orfoliated) calcite, CR: core of internal rib (fibrous prismatic or foliated calcite),
IL: inner layer of crossed lamellar aragonite, CMR: commarginal rib ("radially"
elongate prismatic calcite).

~ Figure S.

Shell microstructure of propeamussiids. All are SEM photographs and show internal surface ofshell with growth direction downward, except for Fig. 5-1, which is an oblique view of fractured surface. Scaleunit in microns.
1-3. Propeamussium watsoni (Smith), from the same locality as Fig. 2-5. 1: Middle part of disk (RV) (UMUT
RMI8287). Slightly weathered outer surface, prismatic outer layer, fibrous prismatic "middle layer" and crossed
lamellar inner layer are observed from the upper to the lower. 2A: Foliated prisms near the periphery of
marginal apron (RY) (UMUT RMI8288). The foliation seems to be Gamma 120 blades. 2B: "Middle layer" offibrous prismatic calcite covering the eroded surface of prismatic outer layer (the same valve). 3A:Outer layer offibrous prismatic calcite partly covered with patches of crossed lamellar inner layer (Ly) (UMUT RMI8289).
3B: Outer layer of regularly foliated calcite (Gamma 135 blades) changed gradually from fibrous prismatic
calcite (the same valve).
4. Polynemamussium intuscostatum (Yokoyama, 1920) from the same locality as Fig. 1-1. "Middle layer" of
foliated calcite (Gamma 135 blades) covering the eroded surface of prismatic outer layer (Ry) (UMUT
RMI8290).
S-6. Propeamussium jeffreysi (Smith, 1885) from the same locality as Fig. 2-3. SA: "Middle layer" of fibrousprismatic calcite showing accretional growth (Ry) (UMUT RMI8291). SB: Distal end of an internal rib showing
accretional growth of the core (the same valve). 6: Outer layer of semifoliated calcite (LV) (UMUT RMI8292).

486

ftaru HAYAMI

Okubo and Inoue (1975) and also in this paper(Fig. 6), each internal rib bears a core of fibrousprismatic (or narrowly foliated) calcite, which isalmost imbedded in the inner layer of crossed
lamellar aragonite. The core is exposed on theinternal surface only at the distal end where its
accretional growth occurs (Figs. 3,5-5B). It must,
therefore, grow like the outer layer in spite of its
situation in the inner layer. In transverse sectionsof the middle part of the disk, each internal rib isrepresented by a lenticular core enclosed with
the inner layer. In ordindary bivalves (including
the Pectinidae) pallial myostracum is formed
along the boundary between the outer and inner
layers, but in propeamussiids, curiously enough,it lies within the inner layer. In Propeamussium
pallial myostracum is formed between the coresof internal ribs and the internal shell surface,broadly waving in accordance with the lenticularcores (Figs. 7-1B,2B).
In Propeamussium dalli from the Caribbean
Sea the internal ribs of LV commonly disappear
in the later growth stage, but such a tendency israrely observed in western Pacific species.
Moreover, the arrangement of internal ribs, inevery Japanese species of Propeamussium and
Polynemamussium so far examined, is perfectly
coincident between RV and LV. Insertion ofshort internal ribs occur simultaneously in thetwo valves. Though the internal ribs (and theircores) are generally thicker in RV than in LV,
their distribution pattern of one valve seen
through from the exterior agrees well with thaton the interior of the counter valve (e.g. Figs.
2-3a,b,c,d, 4a,b,c,d). The internal ribs neverextend beyond the margin of the distribution ofcrossed lamellar aragonite.
Function of internal ribs. Owing to thefleXibility of the marginal apron of RV, the distal
end of each internal rib can be directly in contact
with that of the counter valve, when the valves
are closed (Fig. 4). InPropeamussium sibogai andsome other species of this genus, the crossed
lamellar layer is more extensively distributed in
LV than in RV (Figs. 2-4b,d). Nevertheless, thecontact relation is maintained, because the distal
ends of internal ribs of RV almost reach themargin of the inflexible inner layer. This factstrongly suggests that the internal ribs serve not
only as a frame to support the thin and fragile
shell but also as solid buttresses to counteract
external and internal forces. In this respect thisstructure may be functionally (not genetically)analogous to the auricular crura of free living
pectinids. In Propeamussium the outermost
internal ribs (instead of auricular crura) commonly occur near the boundaries between thedisk and two auricles. They seem to be seriallyhomologous with other internal ribs, even though
two or more cores may be piled up therein.
Most of extant propeamussiids dwell on
deep-sea and low-energy muddy bottoms. It is
generally supposed that predation pressure ismuch weaker in comparison with shallow levelbottoms. Nevertheless, I occasionally meet withinjured-and-repaired shells of Propeamussiumthat indicate non-lethal attacks by some biting
predators (e.g. Fig. 2-5). Though the life mode of
propeamussiids is still poorly known, relatively
large species with internal ribs, except for the~ Figure 7. Transverse sections of the valves of Propeamussium watsoni (Smith, 1885) from the same
locality as Fig. 2-5. All are SEM photographs taken after one minute's etching by 10% acetic acid. Scale unit
in microns.
IA: Lenticular core of an internal rib in the dorsal part of disk near the demarcation line (RV) (UMUT
RM18293).
IB: Lenticular core of the same internal rib in the middle part of disk, not completely separated from the"middle layer".
Ie: Close-up of the same section. Pallial myostracum observed within the crossed lamellar inner layer between the core and the inner surface.
2A: Lenticular core of an internal rib in the dorsal part of disk near the demarcation line (LV) (UMUT
RM18294).
2B: Lenticular core of the same internal rib in the middle part of disk.
2C: Two lenticular cores in the anterodorsal part of the same valve immediately after their origination.

859. Internal ribs of Propeamussium

487

488

ItaruHAYAMI

early byssate stages, probably have swimming
ability to escape from predators.
Thayer (1972) examined the obliquity ofquick (striated) adductor muscle in various
monomyarian bivalves, and tested successfully
the hypothesis that oblique quick muscle isadvantageous for swimming habit because it
enables quicker clapping motion. The quickmuscle of Propeamussium is generally remarkably oblique as exemplified by P. dalli (Thayer
1972, fig. 4A) and P. sibogai (in this paper); theobliquity is comparable with or surpass thevalues in Placopecten magellanicus and Amusium
japonicum which are known as active swimmers.
The reduction of byssal notch with growth andthe widely gaped antero- and postero-dorsal disk
margins also suggest swimming habit.
Reinforcement of valves by internal ribs may
be effective in Propeamussium, because powerfulcontraction of quick adductor muscle forswimming must give considerable strain to thefragile valves. The thicker internal ribs in RV
appear to compensate the relative weakness ofshell strength of RV due to the prismatic calcite
and the absence of external radial SCUlpturing.
Origin of internal ribs. The internal ribs of thePectinidae may have developed as an auxiliary
structure for interlocking of valve margin (Fig.
1-5a). They must have occurred, at least
primarily, in relation to the external radial
SCUlpturing. Although internal shell features ofmany fossil pectinids remain undescribed, conspicuous internal ribs are scarcely known in
pre-Oligocene species. On the other hand,undoubted species of the Propeamussiidae with
distinct internal ribs already appeared in the
Middle Triassic (Nakazawa 1961) and commonlyoccur in Jurassic and later and Cenozoic
off-shore muddy sediments. The genus-levelclassification of fossil and extant propeamussiids
should be reexamined with considering thetaphonomy and differential preservation, but thebasic features appear to be quite conservative.
Internal ribs must have developed independently
in the Pectinidae and the Propeamussiidae,
because, as noted before, they are clearly
different in many essential characters.

As discussed by Waller (1971, 1972, 1978),the Propeamussiidae may have been derived fromthe Late Paleozoic family Pernopectinidae. The
discrepant shell microstructure between RV and
LV was previously described by Newell(1937-1938) in some species of Pernopecten;
the outer layer is prismatic in RV and fibrous in
LV, and the inner layer of both valves is crossed
lamellar. Recently Newell and Boyd (1985) also
described the shell structu.re of Pernopecten sp.
on the basis of some well preserved silicified
specimens. A marginal apron was probably
present also in Pernopecten, judging from the"discrepant" size and shape between the twovalves (e.g. Newell 1937, fig. 42). Internal ribs
are absent, and an ostracum corresponding to the"middle layer" of RV is still undescribed in
Pernopectinidae. This state, however, may not bemuch different from that of some extant speciesof Cyclopecten, in which the "middle layer" isthin in comparison with other layers. In theserespects, Cyclopecten seems to exhibit moreprimitive features than Propeamussium. I presume that Propeamussium (and some related
genera with internal ribs) originated from
Pernopecten through some undescribed Cyclopecten-like species. The development of internal
ribs is probably related to the swimming strategy,
because they are scarcely coexistent with byssal
notch and pseudoctenolium.
In RV of Propeamussium the lenticular coresof internal ribs share common shell microstructure with the "middle layer" (Figs. 5-5A,
5B). Both of them grow accretionally only on
the extra-pallial internal surface and are similarlycomposed of lath-type fibrous prismatic (orregularly foliated) calcite. The "middle layer" issometimes more or less thickened just along theinternal ribs, as recognized in the transverse
sections. Moreover, in serial transverse sections of
RV of Propeamussium watsoni and P. sibogai, it
is actually observed that the cores are sometimes
not completely separated from the "middle
layer" (Fig. 7-1B). Little has been known about
the mechanism producing such a composite shelllayering. Yet, the observed facts seem to indicatethat the internal ribs are produced by some859. Internal ribs of Propeamussium
patchy cells which were inwardly isolated fromthe mantle tissue secreting the "middle layer".
In LV of Propeamussium similar developmental relation may exist between the cores ofinternal ribs and the outer layer of fibrousprismatic (or foliated) calcite. Though theresemblance of shell microstructure is not so
decisive as that in RV, the lenticular core
originates at first from a point adjacent to theouter layer, as exemplified in the transverse
section of early disk of Propeamussium watsoni(Fig. 7-2C).
Conclusion
As the result of this comparative study, thefollowing conclusions were obtained about thestructure, function and development of theinternal ribs of Propeamussium.
1. Each internal rib bears a lenticular core oflath-type fibrous prismatic (or narrowly foliated)calcite, which grows accretionally only at the
distal end in spite of its situation in the inner
layer of crossed lamellar aragonite.
2. Owing to the flexible marginal apron of
RV, the distal ends of internal ribs are just incontact with those of the counter valve when thevalves are closed. They serve solid buttresses tocounteract the destructive force produced by thepowerful contraction of qUick adductor muscle
for swimming.
3. The cores of internal ribs share similar
fibrous prismatic (or foliated) microstructurewith the "middle layer" in RV and with theouter layer in LV. Developmentally, they weremost certainly differentiated from these layers
by some patchy isolation of shell-secreting
mantle tissue.
Homeomorphic relation between Amusium
and Propeamussium can be realized by thedifferent developmental background and primaryfunction of internal ribs as well as many otherbasic features. The Propeamussiidae, which
include Po[ynemamussium and Cyclopecten in
addition to Propeamussium, are commonly
characterized by the striking inequivalveness not
only in the shape and sculpturing but also in the489

shell microstructure. This family should be
regarded as a significant example of "living
fossils", because such strikingly discrepant valves
are common in Paleozoic pectinoids but
unknown in other living pteriomorph families.
The suprageneric classification of the Pectinacea is still in great confusion. It is largely due
to insufficient evaluation of taxonomic characters. As were clarified by Waller (1972, 1984)
and also in this paper, the limit and diagnostic
characters of the Propeamussiidae are very clear
regardless of the presence or absence of internal
ribs, even though their discrimination from the
Pernopectinidae depends on further studies.
Although there are a few fossil genera of dubious
familial position, they are probably not intermediate between the Pectinidae and the Propeamussiidae. Further studies of the shell
crystallography, anatomy, development andecology of propeamussiids would lead us tobetter understanding of the evolution of thesuborder Pectinina.
Acknowledgments
I am very grateful to Dr. Thomas R. Waller(Smithsonian Institution) and Dr. Norman D.
Newell (American Museum of Natural History)
for various stimulation, to Mr. Shoichiro Hayashi(Isshiki Town), Mr. Eiji Tsuchida (Oceanogr.
Inst., University of Tokyo) and Dr. Kenji
Mochizuki (Univ. Mus., University of Tokyo) for
their kind supply of materials, and also to Miss
Tomoko Yamashita and Mr. Akira Tsukagoshi
for their assistance in scanning electron microscopy.

References
B!6ggild, o. B. (1930): The shell structure of themollusks. Mem. A cad. Roy. Sci. Lett. Danmark,sec. Sci., Ser. 9, vol. 2, no. 2, p. 235 -326, pIs.
1-15.
Carter, J. G. and Clark II, G. R. (1985): Classificationand phylogenetic significance of molluscan shell
microstructure. In Broadhead, T. W. (ed.) Molluscs,
notes for a short course. Univ. Tennessee, Dept.
Geol. Sci., Studies in Geology, vol. 13, p. 50-71.

490[taru HA YAMI

Cox, L. R. et al. (1969): Treatise on invertebrate
paleontology, Part N, Mollusca 6. Bivalvia, Vol. 1.
489p. Geol. Soc. America and Kansas Univ. Press.
Habe, T. (1977): Systematics of Mollusca in Japan.
Bivalvia and Scaphopoda. 372p. Hokuryukan,
Tokyo. (in Japanese)
Hayami, I. (1988): Taxonomic characters of propeamussiids from Japan. Venus, vol. 47, p. 71-82.(inJapanese)--and Okamoto, T. (1986): Geometric regularity ofsome oblique sculptures in pectinid and otherbivalves: recognition by computer simulations.
Paleobiology, vol. 13, p. 433-449.
Kuroda, T. (1931): An illustrated catalogue of theJapanese shells (9). Venus, vol. 3, appendix p.
77 -86. (in Japanese)
Nakazawa, K. (1961): Early and Middle Triassic
pelecypod-fossils from the Maizuru Zone, Southwest Japan. Mem Coli. Sci, Univ. Kyoto, Ser. B,
vol. 27, p. 249-279, pIs. 12-14.
Newell, N. D. (1937-1938): Late Paleozoic pelecypods:
Pectinacea. Univ. Kansas, State Geol. Surv. Kansas,
vol. 10, p. 1-123 [1937], pIs. 1-20 [1938).
--and Boyd, D. W. (1985): Notes on micro-fabric in
Upper Paleozoic scallops. Amer. Mus., No vita tes,
no. 2816, p. 1-6.
Okubo, M. and Inoue, T. (1975): Electron microscopyof the geological materials. Part 2. The shellstructure of "Propeamussium ". Mem. Fac. Lit.
Sci, Shimane Univ., Nat. Sci, vol. 9, p. 133-141.
(in Japanese)
Orlov, J. A. (1960 ed.): Osnovy Paleontologii.
Mollusca-Loricata, Bivalvia, Scaphopoda. 300p.
Acad. Nauka, Moscow. (in Russian)Oyama, K. (1944): Classification of Propeamussium.
Venus, vol. 13, p. 240-254. (in Japanese)
Runnegar, B. (1984): Crystallography of the foliatedcalcite shell layers of bivalve molluscs. Alcheringa,
vol. 8, p. 273-290.
Taylor, J. D., Kennedy, W. J. and Hall, A. (1969): The
shell structure and mineralogy of the Bivalvia.

Introduction, Nuculacea-Trigonacea. Bull. Brit.
Mus. (Nat. Hist.), Zool., suppl. 3, p. 1-125, pIs.
1-29.
- - , - - and - - (1971): The shell structure andmineralogy of the Bivalvia. II. Lucina~ea­
Clavagellacea, Conclusions. Ibid., vol. 22, p.
253-294, pIs. 1-15.
Thayer, C. W. (1972): Adaptive features of swimmingmonomyarian bivalves (Mollusca). Forma etFunctio, vol. 5, p. 1-32.
Thiele, J. (1935): Handbuch der systematischen
Weichtierkunde. Band 2, p. 779-1154. Gustav
Fischer, Jena.
Vokes, H. E. (1980): Genera of the Bivalvia: asystematic and bibliographic catalogue (revised andupdated). 307p. Paleont. Res. Inst., Ithaca, N. Y.
Waller, T. R. (1969): The evolution of the Argopecten
gibbus stock (Mollusca: Bivalvia), with emphasis on
the Tertiary and Quaternary species of eastern
North America. Jour. Paleontol.. vol. 43, no. 5,
suppl., p. 1-125, pIs. 1-8.
- - (1971): The glass scallop Propeamussium, a living
relict of the past. A mer. Malacol. Union, Ann.
Rept. for 1970, p. 5-7.
- - (1972): The functional significance of some shell
microstructure in the Pectinacea (Mollusca: Bivalvia). 24th Intern. Geol. Congr. Montreal, Sec. 7, p.
48-56.
- - (1976): The origin of foliated-calcite shell microstructure in the subclass Pteriomorphia (Mollusca:
Bivalvia). Bull. A mer. Malacol. Union, for 1975, p.
57-58.
--(1978): Morphology, morphoclines and a newclassification of the Pteriomorphia (Mollusca:
Bivalvia). Phi/os. Trans. Roy. Soc. London, Ser. B,
vol. 284, p. 345-365.
- - (1984): The ctenolium of scallop shells: functional
morphology and evolution of a key family-level
character in the Pectinacea (Mollusca: Bivalvia).
Malacologia, vol. 25, p. 203-219.

Propeamussium O)P3}jjJO)~~I¥J:to.t lf7t~$I¥J:t~ : =~*ct).lltf;~i'3I!$O)lJe;fln::.~\', '7 ~ 'f::z';I "'" 1::. i1'1 ,j, CPropeamussium) Ii, ';I "'" 1::. i1'1 ,j, CAmusium) .!: ~b'0"O)J:-C'P3}jjJ~~1f-r ~b!, *tiftl¥Jt;::'li~ <14t.c IJ, i!l1=.f(;~JtIlt::.**- t:: Pernopectinidae 0)~11~ .!: cllb ~ i1=. ~ t:: H::fiJ .!: L -etl:§ ~.n~7t~tW-cil>~o Propeamussium o)l:1b, Polynemamussium, Cyclopectenb~ Propeamussiidae 0)~11~~1f-r ~o A,@], -gg:;t(-'HftiBJl,ilZO):m1=.:to J: lff[::fi 1 ~ -V iJ1 J:fll-O)~~t;::,··:)\,'-e, P3}jjJO)gtl'l.l¥J' a.\'ttl'l.l¥J~I1~l!l~L, .:to)~~1¥J . 7t~$I¥J;!;~~~~ Lt::oAmusium ~*td ~ -V iN f40) P3}jjJli , Ill~~ <O)?,\-II-C·?'\-~!(O)1&M}jjJt;::.~ L. -eM$;~.n, ;;$:
*lilll~O)ptJ;.~b-l!t~lit~t;::.-r ~ffll!liJl¥J~i1IU~*t:: L -e \" ~o ;::. .nt;::.)tf L"'C, PropeamussiumO)P3}jjJ~,~m~mBO)P3110)~~~.~mB~ffl-r~~~~0)::z7~~?-eM$;~.n,.:tO)*iIIffi$-C#:hQ$;*-r~o ;::'0)::z7ItjG1=.l¥Jt;::'lt, ti1i.\l:-cltftHtll·jl[rO) "~II" b'6, ti:jj;\!:-C
IUi·llb' 67tf[: Lt::.!: ~ *- 6.n~o P3}jjJ 0) *iIIffi It jilijjj;\!: 0) F,,'-C)tf1i: L. jj;\!:~rtJ L. t::lJi!ft;::.1[H;::.~-r~ J:? t;::.-c~-e\',~o :to.:t6
1ii7kO)t::IlbO)5!lljJt.crtJ1i.\l:WJO)~Nrr1iil~rJJj1{O)jj;\!:t;::.~*-~IilIi*jJ~~61f ~J~ ':I~ AO)~i1IU~:lIU:: L -e\',~ c~ *-~;::. iI!-C~ ~oi!7.\( frr

r

<.

c

Trans. Proc. Palaeont. Soc. Japan, N.S., No. 150, pp. 491-500,3 Figs., June 30,1988

860. LARVAL PALEOECOLOGY OF FIVE BIVALVE SPECIESFROM THE UPPER PLIOCENE OF SOUTHWEST JAPAN*
KAZUSHIGE TANABE
Geological Institute, University of Tokyo, Tokyo 113
and

YOSHIKI ZUSHI
Niihama-Nishi Junior High School, Niihama 792

Abstract Juvenile shells of five bivalve species, Glycymeris rotunda, Limopsis tajimae,
Oblimopa japonica, Crenulilimopsis oblonga and Venericardia panda from the Upper Pliocene
deposits of Kakegawa, Miyazaki and Okinawajima regions, southwest Japan retain theprodissoconch in their initial shell portion. Based on comparison of their prodissoconchmorphology and morphometry with those of modern species hitherto investigated,developmental types of the five species were presumed: direct development for V. panda having
a relatively large (185 -259 pm in length) prodissoconch, and lecithotrophic with a shortnon-feeding pelagic stage for other four species characterized by relatively large (ca. 150-200
pm in length) prodissoconch I and well-marked prodissoconch II. C. oblonga and L. tajimaeboth show remarkable intraspecific variation in prodissoconch II size, and the specimens fromthe northern region generally possess larger prodissoconch II than those from the southern
region.
Judging from the knowledge on larval history of some Recent bivalves in relation to watertemperature and the paleooceanographic setting of the study areas in late Pliocene age, thelatitude dependent variation of prodissoconch size observed in the two species may reflect thedifference in durations of larval stage depending on the changes in temperature of marine
environments.

Introduction

Chanley, 1965, 1966, 1969; Chanley andChanley, 1970; Turner and Johnson, 1971).
These works make it possible to infer. thedevelopmental type of a giwn species from larvalshell morphology with some confidence.
Prodissoconch and early dissoconch morphology can be readily observed in many wellpreserved bivalves with an aid of the scanningelectron microscope (SEM). Comparative analysis
of early developmental stages of living .and fossil
bivalves will, therefore, provide reliable information to understand the evolutionary history,
paleobiogeography and paleoecology of theorganism (Jablonski and Lutz, 1983). In spite ofBivalves secrete a peculiar calcified shell,
named prodissoconch in the early growth stageprior to metamorphosis (Thorson, 1950; Ockelmann, 1965; Jablonski and Lutz, 1980, 1983).
The relationships of prodissoconch morphology,
developmental types, egg and hatching sizes anddurations of embryonic and larval stages in
Recent bivalves have been investigated by anumber of researchers (e.g. Loosanoff et al.,1951; Yoshida, 1953; Loosanoff and Davis,
1963; Ockelmann, 1965; Sastry, 1965, 1979;*Received May 12, 1988; accepted June 10, 1988.

491

Kazushige TANABE and Yoshiki Z USHI

492

this, studies on fossil material are rare (LaBarbera, 1974; Lutz and Jablonski, 1978; Jablonski
and Lutz, 1978). This probably because of the
difficulty in determining the exact taxonomic
positions of fossil larval shells.
This paper describes prodissoconch morphology of five bivalve species from the Upper
Pliocene deposits of the Pacific coastal regions ofsouthwest Japan, and discusses its larval paleoecological implications.

Well-preserved juvenile shells of the following
five bivalve species from these groups are treatedin this paper: G/ycymeris rotunda (Dunker),
Limopsis tajimae Sowerby, Oblimopa japonica(A. Adams), Crenulilimopis ob/onga (A. Adams)
and Venericardia panda (Yokoyama) (Table 1).
These species occur commonly in the study
areas, but specimens retaining the prodissoconch
stage are extremely rare. The juvenile shells
utilized were collected from several localitiesof the Kakegawa, Miyazaki and Okinawa-jimaareas (Fig. 1). According to the previous
planktonic foraminiferal biostratigraphic works(Tsuchi and Ib araki , 1979; Natori, 1979; Tanaka
and Ujiie, 1984), the fossil localities are all
included in the zones of N .19 to N .21 of theUpper Pliocene age (2-3 Ma). The molluscan
assemblages from the Kakegawa, Miyazaki and
Shimajiri Groups are characterized by upper
sublittoral to the upper bathyal associations, andare summarized as the Kakegawa Fauna (Chinzei,

Material and methods

Materia/:-Pliocene marine fossiliferous deposits are sporadically distributed along
the Pacific coastal regions of southwest Japan.
They crop out extensively in the Kakegawa(central Japan), Miyazaki (eastern Kyushu) andsouthern Okinawa-jima regions and the sedimentsin these regions are called the Kakegawa,Miyazaki and Shimajiri Groups respectively.
36"N

126"

132"

134"

136"

138"[

Jr~--~--~~--+-

32" -I---J-+'---¥!~

0)"
30"

. .~g

1-----:1------.1..

')dr........
........

oI---;:~ ....
5km

Takanabe:T.

"~

Figure 1. Map of southwest Japan, showing the fossil localities of the bivalve samples studied.
Pliocene outcrops are horizontally lined (adapted from Tanaka and UjiiG (1984) for Okinawa-jima Island).

860. Larval paleoecology of Pliocene bivalves

493

Table 1. List of material studied. Number of specim~ns used for measurements is shown in parentheses.
Shimajiri Group

Recent

KS1

TS1

St. A

1 (1) 44(36)

4 (4)

3 (3)

3 (3)

13 (5)3 (3)Kakegawa G.
Species

FamilyGlycymerididae

Glycymeris rotunda (Dunker)

Limopsidae

Limopsis tajimae Sower by

OlC

OlK

9 (2)

Miyazaki G.
3805

KT30

16 (3)
16(11)

9 (4)

7 (7)

Oblimopa japonica (A. Adams) 20(16)Crenulilimopsis oblonga(A. Adams)
Cardiidae

Venericardia panda(Yokoyama)

13 (7)

1978, 1986).
In addition to these fossil samples, juvenile
shells of C. oblonga collected from off Osezaki,
northeastern Suruga Bay (Station A, 200-300 m
deep: lat. 35°05'N, long. 138°45'E) were used
for comparison of prodissoconch size. Amongthe five species examined, V. panda is an extinct
species, while others are still living in therelatively deeper environments off southwest
Japan (Habe, 1977). All specimens studied arestored in the University Museum of the
University of Tokyo.
Methods:-Fossil-bearing, silty to fine sandy
sediments were sieved using a Imm mesh screen,
and juvenile shells were extracted from residues
under a binocular microscope. Taxonomic
positions of the juvenile specimens were
determined from comparison of surface ornament and hinge structure with the medium tolarge specimens from the same fossil localities.
Observations of early shell morphology weremade with scanning electron microscopy(Hitachi, S-430), and the dimensions of the larvalstages were measured using a digital micrometer(accuracy ± 1 pm; calibrated by a standard
sample for IC measurement) of the image
processor (Hitachi, EP 1050) attached to theSEM. We followed Werner (1939) and Rees
(1950) for the terminology of bivalve larvalshells.
Prodissoconch morphology
As in other bivalve larvae described previously(Werner, 1939; Rees, 1950; Ockelmann, 1965;
Chanley and Andrews, 1971; Jablonski and Lutz,
1980; among others), the prodissoconch in thefive species examined is divided into two
ecologically and morphologically well defined
stages, prodissoconch I (pd I) and prodissoconch
II (Pd II) (Figs. 2-3). Prodissoconch I is an
initial shell secreted by the shell gland andmantle epithelium during the stage developingfrom the non-shelled trochophore (Carriker andPalmer, 1979). It is fairly similar among thespecies examined in having a D-shaped outline
with a straight hinge line and a coarse andirregularly punctate surface under the SEM (Figs.
2-3). The only difference is that the prodissoconch I in Venericardia panda is less inflated andmore broadly rounded than those of other four
species.
Prodissoconch II is deposited by the mantle
edge along the shell margin and inside theprodissoconch I during the veliger stage (Ockelmann, 1965; Carriker and Palmer, 1979). This
stage is well developed in Limopsis tajimae,
Oblimopa japonica, Crenu1ilimopsis oblonga and
Glycymeris rotunda, but it is absent in V. panda(Figs. 2A-B). In the former four species the Pd I
- Pd II boundary is clearly marked because
concentric growth lines first appear in the Pd II
stage (Figs. 2-3). The growth lines are dense,
fine and regular-spaced in L. tajimae (Figs.
3A-D) , C. oblonga (Figs. 3E-I) and G. rotunda(Fig. 2C), while those in O. japonica are
combination of major undulations and minor
striations (Fig. 2G).

494

Kazu shige TANABE and Yoshiki Z USHI

860. Larval paleoecology of Pliocene bivalves
Dissoconch corresponds to the shell secreted
after metamorphosis. Morphological change at
the prodissoconch-dissoconch boundary differs
among the five species examined. In V. panda aconspicuous constriction occurs at the boundary(Fig. 2B), followed by broad-spaced concentric
growth bands in the early dissoconch stage.
Radial ribs first appear at the stage of about 500
p.m in shell height. In other four species abrupt
expansion of growth line spacing is commonly
observable at the prodissoconch II-dissoconchboundary under the SEM (Figs. 2C, G; 3D, I),
forming a sharp transitional line of demarcation,
named the metamorphic line (Carriker andPalmer, 1979).
Variation of prodissoconch size
Statistical data of the lengths of pr'odissoconchs I and II for the species examined aresummarized in Table 2. Every species has arelatively large Pd I, ranging from 150 p.m to 200
p.m in length.
Intra- and interspecific variation of prodissoconch II length is much larger than that ofprodissoconch I. The length is largest (365-490p.m) in G. rotunda and O. japonica, intermediate(244-415 p.m) in L. tajimae, and smallest(213-328 p.m) in C. oblonga. Concerning C.
oblonga and L. tajimae, the specimens from thesouthern region generally possess a larger
prodissoconch II than those from the northern
region (Table 2).
Discussion
Developmental types in the marine benthic
invertebrates including bivalves are summarized
into three main categories: pelagic development,
direct development and ovoviviparity (Thorson,
1946, 1950; Ockelmann, 1965). Pelagic develop-+- Figure 2.

495

ment is further classified into planktotrophic (=larvae feeding on phytoplankton during theveliger stage) and lecithotrophic (= larvae feedingon their own yolk content during a relatively
short pelagic stage) (Thorson, 1950).
With the development of culture methods,
early life history and larval shell morphology inthe Bivalvia have been investigated for a numberof species by rearing veliger larvae in thelaboratory (e.g. Thorson, 1936, 1950; Yoshida,
1953; Loosanoff and Davis, 1963; Ockelmann,
1965; Chanley and Andrews, 1971; Allen and
Sanders, 1973; Sastry, 1979; Waller, 1981).
Especially Ockelmann's (1965) work on larval
ecology of more than 200 species mainly from
north Atlantic provided adequate criteria torecognize developmental types from larval shellmorphology and morphometry. According to his
work and Thorson (1936), in planktotrophic
larvae, prodissoconch I is small (70-150 p.m in
length), reflecting the low yolk supply, andprodissoconch II is relatively large (200-600 p.m
in length), suggesting a long duration of theveliger stage. In the species having' a lecithotrophic larval development, prodissoconch I islarge (135-230 p.m in length) reflecting thelarge yolky eggs, and prodissoconch II stage isabsent or poorly developed. Species of direct
development type have unusually large(230-500 p.m in length) prodissoconchs, which
are often inflated and broadly rounded with astraight hinge line. Recently, several authors
documented detailed methods to recognize
developmental types in modern and fossil larvalshells under the SEM (Turner and Boyle, 1975;
Lutz, 1977; Jablonski and Lutz, 1980, 1983).
Larval ecology of the five species treated in thispaper is not yet well understood. Comparison of
the results of this study with the criteria
mentioned above may provide a reliable basis todetermine their developmental types. Among theSEM photographs of the early shell growth stage of three bivalve species from the Upper
Pliocene of southwest Japan. Pd I: prodissoconch I, Pd II: prodissoconch II, D: dissoconch. Arrows in B, C, F
and G indicate Pd I - Pd II boundary and/or prodissoconch-dissoconch boundary. A-B. Venericardia panda(Yokoyama). UMUT CM 18273-1 (loc. 3805, Miyazaki Group). C. Glycymeris rotunda (Dunker). UMUT CM
18263-1 (loc. 3805). D-G. Oblimopa japonica (A. Adams). D. UMUT CM 18267-1, E-G. UMUT CM 18267-2(loc. OlC, Kakegawa Group). Scale bars: 50 pm (A), 100 pm (B-E), 150 pm (F-G).

496

'

Kazushige TA NA BE and Yoshiki ZUSHI....

Figure 3. SEM photographs of the early shell growth stage of two bivalve species from the Upper Plioceneof southwest Japan. Pd I: prodissoconch I, Pd II: prodissoconch II, D: dissoconch. Arrows in A- B, D-E , G, andI indicate Pd I - Pd II boundary and /or prodissoconch-dissoconch boundary. A-D. Limopsis tajimae Sowerby.
A. UMUT eM 18266-1 (loc. KT 30, Shirnajiri Group). B-D. UMUT eM 18265-1 (loc. 3805, Miyazaki Group).
E-J. Crenulilimopsis ob/onga (A. Adams) . E-F. UMUT eM 18271 (loc. TSO 1, Shimajiri Group). G. UMUT eM
18269-1 (loc. 3805, Miyazaki Group). H-J. UMUT eM 18269-2 (loc. 3805). Scale bars: 100 ,urn (A- B, E), 50,urn (C , F , G) and 140 ,urn (H, I) .

497

860. Larval paleoecology of Pliocene bivalves
Table 2. Statistical data of the prodissoconch length (in microns) in the five species examined. N: number ofindividuals, X: sample mean, s: standard deviation, V: coefficients of variation, O.R.: observed range.
Species

SampleN

X

Prodissoconch r
s
V

O.R.

N

Prodissoconch II
s
V

X

O.R.

6.0 435-490
27.5
462.5
Grycymeris
2
3
180.6
14.0
7.8 165-199
3805
11. 6 365-461
48.0
413.0
rotunda
2
11.0
189.0
5.8 189-200
2Ole---- - - - - - - ---- - - - - - - - - ---- ---- - ---------- - - -- - - -------------- - - - -- - - --- - - --- - - -- -----2.1 244-260
5.4
253.1
Limopsis
188.1
7
4.5 169-198
KT30
7
8.5
8.1 291-355
312.8
25.4
tajimae4
6.0 163-1913805
4181. 310.9
156-191

11

373.4

31.1

8.3

306-4153.8

175-200

15

416.7

29.1

7.0

375-475

6.7
8.0
9.8

4.0
4.6
5.5

160-178
169-186
153-193

4. 7
7.6
5.6

225-255
213-255
265-3280.9

184-188

240.0
238.3
298.6
300
385

11. 2
18.2
16.8

1.7

4
3
35
1
1

11.9
9.9
10.8

6.0
4.4
4.4

185-214213-240
230-259

OlK

10

176.2

10.3

5.8

Ole

16

190.1

7.2

Crenulilimo.
KS4
psis oblonga TS1

4
3
36
1
3

167.0
174.7
177.6
165
186.3

3
5
7

198.7
224.6
244.6

- --- --------------- ------------ ------------- -O. japonica- ---- ------ -- ------- ---- - - - - - - --- - - - - - - - ------""----- ---- ---------- - - - - - - --------- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - ---

3805
OlK
St. A

V. panda

KS4
3805

ore

five species, only V. panda lacks prodissoconch II
stage, suggesting the absence of a planktonic
larval stage. The prodissoconch I size of thisspecies is rather small to be direct development(ca. 185-259 ,urn), but we infer this mode of
development on the basis of the absence of
prodissoconch II. The four arcoids, Glycymeris
rotunda, Oblimopa japonica, Limopsis tajimae
and Crenulilimopsis oblonga are characterized bya relatively large prodissoconch I (ca. 150-200,urn in length) and a well-marked prodissoconch
II. Not many arcoids have been studied, but themost familiar planktotrophic ones (e.g. Anadaratransversa, A. broughtonii, Noetia ponderosa)
have a small prodissoconch I of 90 ,urn or less
(Loosanoff and Davis, 1963; Chanley, 1966). We
therefore judge the development type of the four
species as lecithotrophic with a short pelagicstage.
As stated briefly, the three limopsids studied
are now distributed in the lower sublittoral toupper bathyal zones (50-2,000 m in depth) of
southwest Japan (Habe, 1977). Of these, L.
tajimae was studied ecologically by Horikoshi
and Tanaka (1980), who recognized yearly
development of relatively large eggs in themedium to large individuals (20-35 mm in shelllength) from the upper bathyal zone (250-450

m depth) off Suruga Bay, central Japan. Oliverand Allen (1980) distinguished two types of egg
and prodissoconch size in seven deep sea speciesof Limopsis from the Atlantic: species fromslope depths having medium-sized eggs andprodissoconchs and species with an abyssal
distribution having relatively large eggs andprodissoconchs. These authors presumed thedevelopmental type of the seven species as
lecithotrophic, although they did not show direct
data. Most species studied by Oliver and Allen(1980) apparently inhabit deeper environments
than the three species studied by us. The resultsof this work and Oliver and Allen (1980) may
suggest a variety of developmental types in
Limopsis, possibly lecithotrophic for species inthe sublittoral to upper bathyal zones and direct
for species in the lower bathyal to abyssal zones.
Among the five species examined, three
species, C. oblonga, L. tajimae and V. panda
show large intraspecific variation of prodissoconch II size. Furthermore, the size in thenorthern individuals is generally larger than thatin the southern ones. Pliocene to early
Pleistocene sediments in the Kakegawa, Miyazaki
and Okinawa-jima areas are now considered tohave deposited in the same paleogeographic
realm, and the fauna is comparable to the living

498

Kazushige TANABE and Yoshizi Z USED

fauna in the waters off southwestern Japan
associated with the warm Kuroshio current(Chinzei, 1978). In the northwestern Pacificalong the Kuroshio, there is a difference insurface temperature of 5-6°C between Okinawa
and central Japan regions throughout a year
(Japan Meteorological Agency, 1987). Such atemperature gradient might have been present in
the Pacific coastal region of southwest Japan in
the late Pliocene age. In connection with thisproblem, an inverse relationship between temperature and maximum size of larval shells has
been reported in Recent species such as Mytilus
edulis (Bayne, 1965) andMya arenaria (Lutz andJablonski, 1978). In laboratory studies, durationof larval stage and the rate of growth of larvaeboth become shorter and more rapid at high thanat low temperatures in Ostrea virginica (Nelson,
1908), O. edulis (Korringa, 1941) and Venus (=Mercenaria) mercenaria (Loosanoff et al., 1951).
These observations indicate that at high temperatures, the high rate of growth is insufficient
to compensate for the short time available forfeeding, and this results in a smaller prodissoconch size at higher temperatures (Bayne, 1965;
Lutz and Jablonski, 1978).
These lines of evidence seem to suggest thatgeographic variation of prodissoconch II sizerecognized in the two species reflect thedifference in durations of larval stage, which waspossibly related to the latitudinal gradient inambient marine temperature.
Acknowledgments
We thank David Jablonski and Richard A.
Lutz for critical reading of the first draft of themanuscript and for useful discussions, and I taru
Hayami for stimulative encouragements. Seiichiro Matsui and Yasuo Kondo gave us valuable information on the taxonomy of the
Limopsidae and also provided Recent specimens
for this study. This work was supported by aGrant-in-Aid for Science Research Fund fromJapanese Government (no. 61480028 in
1986-1987; no. 63540622 in 1988).

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500

Kazushige TANABE and Yoshizi ZUSIU
Kakegawa mJII, Miyazaki -g~, Shimajiri !il;8i., Takanabe ii1iiM, Sakamoto 1&*, Kochinnda
JlI.3JZ, Tamagusuku .:E:~, Osezaki *i!fiJi~, Suruga Bay ~fiiJf.1i.

*~j¥HI*J:$ff~~~=tlcFl. 5~0)#J~tt~~: =tlcFl.~IHi, :¥e~O):mM~;::JJii:rt.!!: (prodissoconch) C Jl~IiI'!.tLG~lil¥.Jt.crt.!!:~'"? < G. JJii:rt.!!:fi ~ I?~;::, ~~t!l!i0)JJii:rt.!!: I (prodissoconch I) H~Il;Q'
t.cIWJ,L'Fl}jj]~t!I!i;Q'l?t.cGJJii:rt.!!: IT (prodissoconch II) 1;::IRZU~.tL, -t:.tL.:e.tL~{l:J:.).1itr, ~{l:~0)#J~M~;::~nX;~.tLG. A,@], ~mB*:;t3JZr.FJ;j!I;::5t;(Pi"GmJII~~, -g~~~, !il;8i.~~o)lililWJ~& (2 - 3 Ma) ;Q' I?~ L t.:=tlcFl. 5 ~ (Glycymeris rotunda, Limopsis tajimae, Oblimopa
japonica, Crenulilimopsis oblonga, Venericardia panda) 0) JJii:rt.!!:~f&~ L, :m.~~ O)ff;jSj- c O).It
il'E;Q'I?-t:.tLI?O)#J~tt~1!.~~~~ Lt.:. ~~ Lt.: 5 ~O)? ~ V. pandafi, *~0)JJii:rt.!!: I ~1fi" Gto)O),JJii:rt.!!:II~~<~c;Q'I?,.~:¥e~~K~i"Gc~~I?.tLG. -t:0).0)4~~, • • *~0)JJii:rt.!!: Ie, !Jij~t.cJJii:rt.!!: IT ~#'"?~ c ;Q'I?, N~*~~I;::~ L.ltil'EI¥.J1ill~,r.Ut#J~M~#'? ""C~,t.:c m~~.tLG. ~ I? I;:: C. oblonga c L. tajimae I;::'"?~'""c fi, J: IJ ~tO):I1!!~O)l'-*li c, JJii:rt.!!: II 0)~1X~*~~'~c~h~'?~ :m.~~K~~G*~c~.L~#J~~m~O)~-~.,~Mff~i!t~IJ;fI;::~~ G tt#ar.F~I¥.JWjjl-;Q' I?';'""c, ~-t: I? < ii!!i~I;::';'I?.tLt.:JJii:rt.!!: II 0)~1 ;(O):I1!!l!I!l¥.J~~fi, *~I;::mifiU~.tLt.:r.¥lt#J~MO):llt~ O)it~';Q' I?~ t:~ t 0) cm~~.tLG.
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ErrataNo. 149, 855. MATSUOKA, Keiji:
Pliocene Freshwater Bivalves (Lamprotula and Cuneopsis: Unionidae) from theIga Formation, Mie Prefecture, Central Japan.
P. 419, 421, 423, 425, 427, 429 running title read 855 for 856.
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Transactions and Proceedings of the PalaeontologicalSociety of Japan

June 30, 1988

New Series No. 150

CONTENTS
TRANSACTIONS
856. KOBAYASHI, FUn?o: Late Paleozoic foraminifers of the Ogawadani Formation,southern Kwanto Mountains, Japan .. .. .. .. . . .. . .. . . . ... . ... . . .. .. . . 435
857. IGO, Hisayoshi, IGo, Hisaharu and ADACHI, Shuko : Permian sphinctozoan sponges
from the Ichinotani Formation, Hida Massif, central Japan. . . . . ...... . .... . 453

858. MATSUMOTO , Tatsuro and MOROZUMI, Yoshiro: A sphenodiscid ammonite acquiredrarely from the Cretaceous of Japan ......... ..... .. . . ... . .... . . ... .. 465
859. HA YAMI, Haru : Functional and taxonomic implications of internal ribs ofPropeamussium ... . . . . ........ . . . .. . .. ... .. . ... . .. .. .. ... . . .. 476
860. TANABE, Kazushige and Z USHI, Yoshiki : Larval paleoecology of five bivalve species
from the Upper Pliocene of sou thwest Japan .. ; . . . . . . . . . . . . . . . . . . . . . . . . 491