Taxonomic and phylogenetic investigations were carried out on the Eocene and Oligocene radiolarians assignable to the genus Theocorys from submarine sections of the Southern Indian and Southern Atlantic Oceans. Several well-preserved theoperid species previously described under the genera Calocyclas, Cyrtocapsella or Theocorys are now grouped into Theocorys, and their phylogenetic relationships are discussed. Five species are described, of which three are proposed as new. They are : T. kerguelensis sp. nov., T. minuta sp. nov., T. saginata sp. nov., T. robusta comb. nov. and T. semipolita comb. nov. In addition, another new species, Calocyclas (?) nakasekoi, is described.

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Two ammonite species of the genus Mortoniceras have been recently obtained from two stratigraphic units, Member Ld of the Lower Yezo Subgroup and Member Mb of the Middle Yezo Subgroup on the Tengu-zawa route of the Yubari Mountains, central Hokkaido. They are identified respectively with Mortoniceras (Mortoniceras) cf. geometricum Spath and Mortoniceras (Mortoniceras) rostratum (J. Sowerby). M. (M.) geometricum, which is taken here as allied to M. (M.) pricei (Spath), probably includes some specimens described as Pervinguieria arietiformis by Haas (1942b) from Angola and as M. (M.) arietiforme by Renz (1971) from Venezuela. Our study of Mortoniceras (Mortoniceras) rostratum suggests that Ammonites rostratus J. Sowerby should be systematically assigned to Mortoniceras (Mortoniceras) rather than to M. (Subschloenbachia). On the evidence of the two ammonite species, Member Ld is correlated with the middle part (probably the Hysteroceras varicosum Subzone) of the Upper Albian and Member Mb with the upper part (probably the M. (M.) rostratum Subzone) of the same substage. Therefore, no significant time gap exists at the boundary of the Lower and Middle Yezo Subgroups.

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The archeopyle type in modern dinoflagellate cysts is classified into the following saphopylic, theropylic and cryptopylic types. Within the saphopylic type, Tuberculodinium vancampoae (=cyst of Pyrophacus steinii) is the only species generally accepted as having an archeopyle developed on the hypocyst. However, the archeopyle type of this species has been alternatively explained as being precingular rather than hypocystal. New observations have led us to conclude that the archeopyle of T. vancampoae is neither hypocystal nor precingular, but epicystal in type. Specimens of the hypnozygote of P. steinii recovered in a plankton sample from Omura Bay, West Japan show archeopyle sutures formed neither on antapical nor precingular sides but on the apical side where they are topologically related to the distribution of large and barrel-shaped processes and remaining thecal plates that overlap the hypnozygote. The hypnozygotes of P. steinii, wrapped in their planozygotic thecae, were carefully observed at germination during an incubation experiment. One of the living hypnozygotes was still enveloped by the thecae of the planozygote. Then, several weeks after the encystment, a motile cell germinated from the hypnozygote through one opening (=archeopyle) formed on one flat side. Since the thecae of the planozygote was still attached to the surface of the hypnozygote, the position of the germination site was easily determined with relation to the thecal plates. Above the archeopyle consisting of two paraplates, the apical pore plate with two furrows was observed. It is clear that the archeopyle was formed not on the antapical but on the apical side.

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A trogosine tillodont, represented by seven fragmentary teeth, is described from the upper part of the Akasaki Formation, early Middle Eocene of Japan. The stratigraphic horizon of the new material is almost the same as that of the holotype of Higotherium hypsodon, which is the most recently described tillodont from Japan. In spite of poor preservation, the dental characters of the new specimens are distinguishable from those of the Asian trogosine genera including Higotherium, and they may be referable to Trogosus, which has been recorded only from the Bridgerian of North America. This Trogosus-like tillodont inhabited East Asia together with more advanced Higotherium during the early Middle Eocene.

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We have examined the genus-and species-level taxonomy and distribution of the ocenebrine muricid gastropod genus Ocinebrellus Jousseaume, 1880. The genus comprises two stocks. The O. inornatus stock includes O. inornatus (Recluz, 1851) and O. Iumarius (Yokoyama, 1926). The O. aduncus stock comprises O. aduncus (Sowerby, 1834), O. protoaduncus (Hatai and Kotaka, 1959) and O. ogasawarai sp. nov. Since its first appearance during the middle Miocene, Ocinebrellus has been limited to the warm-and cool-temperate shallow seas of northeastern Asia.

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