Abstract
A male Japanese raccoon dog (Nyctereutes procyonoides viverrinus) collected from Kanagawa-ken is remarkable for having the Robertsonian fission of three chromosomes, nos. 5, 8 and 11. By such a fission these chromosome pairs are heteromorphic in respect to two acrocentrics and one metacentric. The karyotype of this specimen is also characterized by having two to four B-chromosomes. Most cells have 3 B's (59.6%) and 4 B's (36.1%). By such a variation of B's, this specimen is to be mosaic consisting of mainly two cell types; 2n=44 chromosomes (39 autosomes+XY+3 B's) and 2n=45 (39 autosomes+XY+4 B's).
