Chromosomes of six species of Indian snakes

The karyotypes of six species of snakes belonging to the families, Colubridae, Elaapidae, Viperidae and Hydropidae are described. in chrysopelea omata(Colubridae) the sex chromoseomes are morphologically indistinguishable, whereas, in Bungarus fasciatus (Elapidae) and Vipera r. russelli (Viperidae) they are distict because of the minute size of the W chromosome. in dryophis nasutus (Colubridae) and hydrophiso. omatus (Hydrophidae) also, the sex chromosomes are morphologically distinguishable because of the heteromorphism of Z and W chromosomes, but the W chromosome in the former is larger than the Z and in the latter similar in size but different in morphology. there is no similarity in the known karyotypes of the families Elapidae and Hdrophidae. it apparently justifies the separation of the two families. detailed autoradiographic study using 3 H-TdR in the ♀ of the banded krait reveals for the first time, asynchrony in the replicating pattern of the Z chromosome.