The species Archidoris tricolor (Baba, 1938) is redescribed anatomically and a new species, A. sugashimae, is also described.

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Microliotia is a caenogastropod genus and was represented by the monotypic species M. brandenburgi Boettger from the Miocene of Rumania. Previous authors regarded Microliotia as a junior synonym of Sansonia, which is currently regarded as a member of the family Pickworthiidae. This is the second installment of descriptions of new species in the family Pickworthiidae from submarine caves and caverns in the tropical Pacific. Seven new species of Microliotia are described : Microliotia ohashii, Microliotia koizumii, Microliotia fenestrata, Microliotia hawaiiensis, Microliotia mactanensis, Microliotia suturalis, and Microliotia pumilis.

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Morphological features of the hinge during larval and early postlarval development of Barnea manilensis (Philippi), especially during metamorphosis, are described using optical and scanning electron microscopy. After the beginning of the metamorphosis, B. manilensis begins to rotate the two valves around the dorso-ventral axis, which is emphasized as effective boring motion. Relationships between the hinge development and the dorsoventral rotation are discussed. The dorsal pivot of the dorso-ventral rotation is initiated by the first fibrous ligament. In the early postlarvae, antero-ventral margins, separately opened by the rotation, become wider with overlapping the postero-dorsal parts to slide the left valve inside the right. In the hinge area, the overlapping is adjusted by left chondrophore, which is located on the left valve inside the right. In the subsequent early postlarval stage, the first fibrous ligament reduces while the dorsal condyle develops into a knob. The dorsal pivot of the dorso-ventral rotation secondarily shifts from the first fibrous ligament to a point touching two dorsal condyles.

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We examined the two Neogene species of the ocenebrine muricid gastropod genus Ceratostoma Herrmannsen, 1846, from Japan and North Korea, namely, C. makiyamai (Hatai & Kotaka, 1952) and C. sp., both from the early middle Miocene. The genus Ceratostoma is divisible into four groups based on C. nuttalli (Conrad), C. virginiae (Maury), C. foliatum (Gemelin), and C. rorifluum (Adams & Reeve). Three Miocene species from Kamchatka assigned by Russian workers to Ceratostoma are difficult to evaluate owing to poor preservation. Purpura turris Nomland, from the Pliocene of California, which was assigned to Ceratostoma by earlier authors, is here tentatively assigned to Crassilabrum Jousseaume, 1880. The genus Ceratostoma may have arisen in the Atlantic. By the early Miocene, it had reached California, and then spread westward to northeast Asia by early middle Miocene time. This pattern of east to west expansion during the early half of the Miocene also characterizes many other north-temperate marine genera, including the ocenebrine Nucella.

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One juvenile specimen of Architeuthis species was collected from the waters south off Central Honshu, Japan. This specimen is characteristic by the silvery iridescent skin with distinct reddish chromatophores, long and slender mantle, short and subtriangular fins, proportionally large head, and short and robust arms. The depth of the present collection of this specimen was shallower than those in previously estimated. This is a first record of juvenile Architeuthis from the Northwest Pacific.

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Growth and number of newborns in Semisulcospira nakasekoae reared during 48-61 months under the laboratory conditions were studied. The newborns, which were produced in June 1990, Oct. 1990 and May 1992, grew up to 8.0-8.4 mm in mean shell diameter at age 1, 9.2-9.3 mm at age 2, 10.2-10.8 mm at age 3, and 10.3-10.9 mm at age 4. The maximum size of S. nakasekoae was 13.4 mm in shell diameter, 29.1 mm in shell height, 3.3 g in wet weight with shell at age 4+. The production of newborns has begun in snails grown up over 8 mm in mean shell diameter at the 10-12th months after the birth. Birth of newborns occurred at a water temperature between 8 and 32℃. Large number of newborns were produced at a water temperature over 20℃. Number of newborns produced during a month per female was estimated 3-10 individuals at a water temperature between 20 and 32℃. Large number of newborns during one year were produced by mature females larger than 9 mm in shell diameter at age 1 to 4+. Mean number of newborns produced during a year per female at age 1 to 4+ was estimated 26-33 individuals.

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