Ultrastructural observations revealed that the orange whiskered bat belongs to the‘prolonged sperm storage’type, in which copulation takes place probably in late October and ovulation occurs after arousal from hibernation in spring. The principal site of sperm storage was the caudal isthmus of the oviduct, where spermatozoa had intimate relationships with indentations of the non-ciliated epithelial plasma membrane, but some dead spermatozoa were engulfed by the epithelial cells. Abundant glycogen found in the non-ciliated epithelial cells was regarded as a nutrient source for prolonged sperm storage. Considerable numbers of spermatozoa were observed also in the uterus and uterotubal junction. A single Graafian follicle found in either ovary had an oocyte with a germinal vesicle at the dictyotene stage in prophase of meiosis I (resting stage) throughout hibernation from early November to late March, while the oocyte in the bats administered with gonadotrophic hormones in late March was in anaphase of meiosis I. Heavy glycogen content in the cumulus cells may be of nutrient value for the prolonged survival of the ovum. The ‘prolonged sperm storage’type was considered as a reproductive strategy for species preservation, by which their young are adjusted to be born in hot summer when insect food is abundant.

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The karyotypic features of two Japanese species ofMurina, Mu. aurata and Mu. leucogaster, were investigated in detail using conventional and G- and C-band stainings. Their karyotypes were identical with each other (2n=44, FN=56) . The comparison of conventionally stained and G-banded autosomal elements between twoMurinaspecies andMyotis hosonoishowed no detectable difference in size, shape and band in the corresponding autosome pairs between both genera, except for the morphology of three medium-sized pairs (nos. 10-12; ST-elements inMurinaand A-ones inMyotis) and the banded segments around their centromeric regions. All of these ST-autosome pairs inMurina, as well as the majority of other autosome ones, did not contain C-band materials, although most of the autosomal elements inMyotis, including nos. 10-12 pairs, had a substantial amount of C-band materials mainly in their centromeric regions. Taking the karyological data mentioned above into consideration together with the phylogenetic relationship betweenMurinaandMyotis, it is suggested that the three pairs of ST-autosomes inMurinahave evolved from the same-sized A-elements (nos. 10-12) ofMyotisby pericentric inversions, and the extensive deletion of heterochromatin has taken place also in the process of this karyotypic alteration or later.

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A Karyotypic comparison between JapaneseMyotisandPipistrelluswas made using C-, G-, and Q-band patterns. The karyotypic difference betweenP. endoiandP. abramusresulted from a reduction in the 2n and FN due to some mechanisms comprising non-Robertsonian rearrangements, together with the addition of heterochromatin which differs in nature from that of Myotis.

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Skull character and dental pattern were described and 16 skull measurements were given in 14 specimens ofMicrotus kikuchii. The skull was rather large but less ridgy and angular. The number of re-entrant folds varied greatly at both sides in M3: three inner and outer folds are most frequent among the specimens examined. The number of closed dental spaces of M3 varied from four to six, and five ones were most common. The antero-external concavity of the anterior loop of M1 varied from indistinct to distinct type. A prominant first outer fold of M3 is observed in all specimens studied, and it suggests that the fold is a characteristic of the vole. The re-entrant fold of the second loop of M3 did not appear consistently. Significant regression coefficients of seven skull measurements on zygomatic width (ZW) were shown except for interorbital width. By a regression line of condylobasal length (CBL) on ZW, the 95% confidence interval for CBL of the holotype specimen, whose basal part of braincase is damaged, was estimated as 30.97-31.99 mm, which is longest among the specimens examined and reported.

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The process of microwear production on the occlusal surfaces of carnassials was investigated secularly. Three dogs were fed on artificial food, containing dried leather, live stock bones and meat with carborundum or soil. Replicas of the occlusal surface were observed at regular intervals. The occlusal surface was divided into two areas (pit area and striation area) each of which had a different kind of microwear. The pit areas appeared along the edges and the groove between the lobes, corresponding to the actual contact of the teeth. The striation area was the rest of the occlusal plane. The feature of these areas and microwear were altered by various foods and seemed to reflect some of the characteristics of the food. However, the microwear can not be an accurate measure to identify the kinds of diet taken by the animal and rather represents the functional aspects of the teeth, i. e., how they are used in mastication.

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Food habits of the feral mink (Mustela vison) were studied in Hokkaido. Four hundred and fifty eight droppings collected from three areas, Barato, Nemuro and Kushiro, from October 1983 to November 1984, were analyzed. Mink ate a wide variety of prey, consisting mainly of mammals and fish. The importance of amphibians was locally variable. Birds, crustaceans, insects and others were supplementary foods. Monthly variations in the food habits was recorded in the level of predation on fish and mammals in Barato. Interspecific competition for food between the mink and the Japanese weasel (Mustela itatsi) was suggested.

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