It has been determined that a total of 17 species in the world belong to the genus Cythere s.s. All of these species occur exclusively in the coastal areas of the northwestern and northeastern Pacific and the North Atlantic. The genus is restricted to areas north of the Tropic of Cancer. Cythere species are most diverse around the Japanese Archipelago and neighbouring areas. Cythere species are most diverse around the Japanese Archipelago and neighbouring areas. Cythere first appears in the Miocene, and a total of 12 species, including 9 Recent ones, have been found so far in and around the Japanese Archipelago. On the other hand, only 4 species are found in the northeastern Pacific and only 2 along the northern Atlantic coastal areas. The northeastern Pacific and Atlantic forms are all found in Pliocene or younger deposits. The Cythere species are classified into five species groups on the basis of morphological characteristics. We hypothesize that these groups have been formed in the process of speciation. Members of a group have closer affinities with each other than with a members of any other group. We have re-examined ten species which are already known to science, and we describe 7 new species. The new taxa are C. cronini, C. hanaii, C. kamikoaniensis, C. nopporoensis, C. sanrikuensis, C. valentinei, and an unnamed species.

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Adnatoceras ichinotaniensis, sp. nov. is described from a late Bashkirian (Middle Carboniferous) limestone of the Ichinotani Formation in the Fukuji district, central Japan. This species is morphologically characterized by the following features; (1) subcircular cross-section of the shell in early stages, (2) position of the siphuncle shifts ventralwards to some degree from center as the shell grows, and (3) episeptal-mural and hyposeptal deposits are well-developed in apical portion. The genus Adnatoceras has previously been known only from Western Europe, U.S.S.R. and North America of Middle Devonian to Late Carboniferous time.

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Corals are abundant in the lowest part of the Omi Limestone, Central Japan. An assemblage of corals obtained from the lowest part in the Fukugakuchi area comprises more than 13 forms, from which the following five species including three new species are herein described and illustrated : Cyathaxonia cfr. C. cornu Michelin, Clisiophyllum kurohimense, sp. nov., Akiyosiphyllum stylophorum Yabe and Sugiyama, Carcinophyllum hasegawai, sp. nov. and Hiroshimaphyllum simplex, sp. nov. This coralline fauna is correlatable with that of the Nagatophyllum satoi Zone of the Akiyoshi Limestone, Southwest Japan, and indicates Late Visean in age.

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A molluscan assemblage composed of twelve species occurs in the Miocene Kozono Formation, near Yorii, Oosato-gun, northern Saitama Prefecture. This assemblage is considered to have lived in a tidal sandflat near to an estuary and is comparable to the estuarine tidal flat community, characterized by arcids and potamidids, of the early middle Miocene Kadonosawa-type Fauna. The four species of Potamididae, Tateiwaia tateiwai (Makiyama), T. yamanarii (Makiyama), Vicaryella atukoae (Otuka) and V. ishiiana (Yokoyama) are described for the first time from the Kozono Formation.

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Triassic Radiolaria from bedded chert and Jurassic Radiolaria from siliceous shale in the Nadanhada Range, Northeast China are described; they are Capnodoce traversi, Eucyrtidiellum ptyctum, E. unumaense, Guexella nudata, Livarella validus, Parahsuum (?) sp. A, Pentactinocarpus sp. A, Poulpus curvispinus, Pseudostylosphaera japonica, p. cf. hellenica, P. cf. tenue, P. sp. A, P. sp. B, P. sp. C, P. sp. D, P. sp. E, Stichocapsa convexa, Triassocampe deweveri, T. sp, A, Tricolocapsa (?) fusiformis, T. plicarum, T. tetragona, T. cf. ruesti, Yeharaia annulata, Y. japonica and Y. sp. A. Other genera (species undetermined) are also illustrated. Ages of the bedded chert and siliceous shale are assigned to middle to late Triassic (late Anisian to Ladinian; late Carnian to Norian), and to middle Jurassic (Bathonian to Callovian), respectively.

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Attenuatella bandoi, sp. nov. is described from the Upper Permian (Djulfian beds) of the lower Toyoma Formation of Ishihama, Utatsu district, southern Kitakami Mountains, northeast Japan. The genus Attenuatella is distributed in Middle Carboniferous (Moscovian) to Upper Permian (Dorashamian) strata of Spitzbergen, Soviet Arctic, Siberia, Urals, northern Yukon, west Texas, northern Mexico, eastern Australia, New Zealand, New Caledonia, northern Thailand, northern China and northeast Japan, mostly in the Lower and Middle Permian of the Boreal and Gondwana Provinces.

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Taphonomy of ammonites in the Cretaceous Yezo Group has been discussed on the basis of field and laboratory observations of many specimens from the Tappu area, northwestern Hokkaido. The Cretaceous deposits in the study area are represented mainly by monotonous, off-shore muddy sequence attaining several thousand meters thick, and yield numerous ammonites and other molluscan fossils at varioius horizons. Ammonite fossils are preserved in both calcareous concretions and surrounding mudstone. Most specimens from a well-laminated mudstone of the lower stratigraphic levels [lower to middle Cenomanian] are large-sized, and have been suffered compaction and dissolution, even they are preserved in calcareous concretions. On the contrary, ammonites including immatures, are quite well preserved in spherical or mushroom-shaped calcareous concretions, embedded in intensely bioturbated mudstone of the upper stratigraphic levels [middle Turonian to upper Santonian]. Such concretions might have consolidated in earlier stage than those of the lower stratigraphic levels before ammonite shells suffered diagenetic damage. Intermediate preservational features are observable in the uppermost Cenomanian to the lower Turonian. Large ammonites, occurring solitarily in mudstone are generally much poorly preserved than the moderate-sized ones. Several interesting mode of preservation : for example, "half-ammonite" and "ventral-tire", are observable at various horizons in the area surveyed. Because of preservational uniformity of "half-ammonites" belonging various taxa and occurring from various horizons, the mode of preservation may be originated from partial sedimentary filling in phragmocone, prescribed by position of septal neck, and diagenetic compaction and shell-dissolution after complete burial. Ammonite shells and plant remains were drifted similarly and accumulated at the same places as patches on the sea floor. In some cases, they are concentrated in lower umbilical void of horizontally laid large ammonite shell. Large ammonite shells might probably trigger off such accumulations, acting as a "trap" on the sea floor. Some spatangoids, preserved regularly in the umbilical void of large ammonite, might assemble to eat organic matter accumulated there.

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Burrowing depths of 22 infaunal bivalve species living in the Japanese coastal areas were observed. Burrowing depth of each species is variable depending on the shell size, substratum, and other environmental attributes. The most striking is ontogenetic variation : In most species, maximum burrowing depth tends to increases with the increase of shell size. Difference in burrowing depth among species represents different life habit in bivalves. Particularly, the difference is pronounced, between extremely deep burial (more than 30 cm) of immobile bivalves like Panopea japonica A. Adams and shallow burial (less than 15 cm) of most bivalves capable of active movement. In suspension-feeding siphonate bivalves, the ratio of pallial sinus length to shell length (Pallial Sinus Index) is closely related to the relative maximum burrowing depth. This "sinus-depth relation" may be useful in inferring burrowing depth of extinct species.

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Six species of the genus Caestocorbula Vincent, including three new species, C. antiqua, sp. nov., C. monobensis, sp. nov. and C. ohtai, sp. nov., are described from ten localities of the Cretaceous in Japan.

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The Akiyoshi Limestone Group (Early Carboniferous to Middle Permian) in Yamaguchi Prefecture contains a diverse fossil molluscan fauna, including cephalopods. In this paper, we describe for the first time 6 species of orthocerid cephalopods from the Isa area where lies in the southwestern margin of the Akiyoshi Limestone Plateau (s.l.). Stratigraphic levels and lithofacies of the cephalopods locality are divided into two types i.e., 1) Bioclastic grainstone, rich in crinoid fragments, of the Pseudostaffella antiqua zone (Bashkirian) including Brachycycloceras sp. indet. and 2) Coquinite of the Fusulinella biconica zone (Moscovian), limestone of which yields Brachycycloceras akiyoshiensis, sp. nov., Geisonoceras sejunctus, sp. nov., Geisonocerina cribrella, sp. nov., Striacoceras (?) sp. indet. and Reticycloceras (?) sp. indet.

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Karsteniceras obatai, sp. nov., (Ancyloceratinae) from the Barremian Kimigahama Formation of the Choshi area, Kwanto district is described. The classification and phylogeny of heteromorph ammonites at supra-superfamily level is discussed on the basis of the internal shell features of the early ontogeny in this species. K. obatai is allied to Karsteniceras asiaticum (Yabe et Shimizu) in shell form ; both possessing a ventral groove on the middle stage of each chamber, but the new species is distinguished by the stoutly ventro-lateral tubercles on the ribbing at mid-whorl and by the numerous lirae on the later whorl. These two species are considered to have derived from a common ancestral species. Some internal structural features of the nepionic stage of the shell of K. obatai are observable. One of the features, the siphuncular position, is interpreted as providing an important evidence for the classification and phylogeny of heteromorph ammonites at ordinal level, and that the existing classification of these ammonites is polyphyletic.

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