Body size and age structures of two breeding populations of Rana tagoi tagoi were studied in southwestern Kanto. The mean snout-vent length of males and females was 42.2 and 44.2mm in Kanagawa, and 41.7 and 42.2mm in Tokyo, respectively. The populations studied exhibited almost no sexual dimorphism in body size. Rana. t. tagoi was successfully aged by skeletochronology using phalanges. The breeding adults were 2-4yr old and the age at first reproduction was estimated to be 2-3yr. Their lifetime growth schedule was also estimated, based on the relationship between body size and age.

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Chromosome analyses were performed using adults and embryos of Onychodactylus japonicus obtained from four localities in Honshu Island. The diploid chromosome number of O. japonicus was 78. Morphological variation was observed in chromosome No. 4. Three types of chromosome No. 4 were evident in samples from Tsukui and Hinoemata, two types in the Tateyama sample, but only one type of chromosome No. 4 was found in the Jogakura sample. The morphological variation of chromosome No. 4 is considered to be autosomal, and not due to morphological differentiation of sexchromosomes. Use of the C-banding and R-banding methods revealed no interstitial multiple bands in any chromosome arms. The C-banding pattern of O. japonicus is similar to that of O. fischeri.

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Mating in the southern Kyushu population of the Japanese mamushi, Agkistrodon blomhoffii blomhoffii, occurred in August and September. The largest ovarian follicles of mated females were 6mm or more in length, whereas those of unmated females were usually less than 6mm in length. In addition, body mass was significantly greater in mated females than in unmated ones. These suggest that in females of the Japanese mamushi, mating is strongly associated with ovarian follicle development and body mass.

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The shape and size of spermatozoa of 11 Japanese salamander species were examined with scanning electron microscopy. In hynobiid and cryptobranchid species, about an anterior quarter of the sperm head was covered with an acrosomal sheath, and the perforatorium emerged by detachment of the sheath. In two salamandrid species, the acrosome and the nucleus could not be discriminated externally. They had an acrosomal barb at the tip, which was lacking in the hynobiid and cryptobranchid species. Sperm sizes of Pachypalaminus boulengeri, Salamandrella keyserlingii and Andrias japonicus were within the range of those of five Hynobius species (163-272μm), whereas the sperm sizes of the two Cynops species were much larger (about 490μm). Onychodactylus japonicus had the largest (about 550μm) sperm among the Japanese salamanders examined.

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