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The present paper deals with the karyotype analysis of 22 Japanese raccoon dogs collected in Ishikawa, Yamaguchi, Osaka and Wakayama prefectures, Japan. The basic chromosome number of these specimens is 2n=38, but the higher number of the chromosomes than the basic one has been observed in all specimens, because the B-chromosomes are included in all of them. Among the 22 specimens, the Robertsonian fission of one metacentric element has been observed in 3 specimens.

Karyotypes of Rhinolophus pusillus (2n=62), R. affinis (2n=62), R. stheno (2n=62), R. marshalli (2n=62), R. yunanensis (2n=60) and R. luctus perniger (2n=32) from Thailand are investigated. The karyotype evolution in these species seems to be due to the Robertsonian fusion from the species with 2n=62.

Karyotypes of two Japanese insectivorous species, Crocidura dsinezumi chisai (2n=40, FN=52) and C. horsfieldi watasei (2n=26, FN=48), are investigated by G- and C-banding pattern analysis. Based on the G-banding patterns it is suggested that the 7 meta- or submetacentric pairs observed in C. h. watasei have been developed by the Robertsonian fusion of 10 acrocentric pairs, and also the centromere-telomere translocations between two subtelocentric and acrocentric pairs included in the C. d. chisai karyotype.

Frequencies of the acrocentric homomorphic (A/A), the acrocentric and subtelocentric heteromorphic (A/S) and the subtelocentric homomorphic (S/S) types in the pair nos. 1 and 9 of the black rats are examined in 46 specimens collected in the Osaka-city of Japan. A considerably high frequency of the A/S and the S/S types observed in these specimens is rather similar to those distributed in the Kanto district of Japan. These features are explained by the historical migration events of the black rats.

The karyotypes of three black rats collected in Kota Kinabalu, Sabah, Borneo, and one specimen collected in New Caledonia are analysed. The former three black rats are the Asian type having 42 chromosomes. Among them no. 1 chromosomes are characterized by having all subtelocentric pair, but pair nos. 9 and 13 are polymorphic with regard to the acrocentric and subtelocentric chromosomes. One specimen from New Caledonia is characterized by a typical Oceanian type idiogram with 38 chromosomes.

Chromosome polymorphism due to the A/A, A/S and S/S types of the pair no. 3 in the Norway rat (Rattus norvegicus) collected in Osaka prefecture has been observed in 48 specimens. Although these three chromosome types are observed, the frequency of the A/A type is the highest. These results are compared with those obtained in the Misima population published previously (Yosida and Amano 1965).