The B-chromosomes and the Robertsonian fission in two Japanese raccoon dogs (RD-8501 and RD-8503) collected in Kanagawa-ken are described in the present paper. The RD-8501 specimen is characterized by having an equal number of two cell types with 2 and 3 B-chromosomes. The other specimen, RD-8503, having three cell types due to 2 B's, 3 B's and 4 B's, is remarkable by having a single Robertsonian fission of the pair no. 5.
Karyotypes of Rhinolophus pusillus (2n=62), R. affinis (2n=62), R. stheno (2n=62), R. marshalli (2n=62), R. yunanensis (2n=60) and R. luctusperniger (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.