“…In Serpentes, chromosome inversions and alterations in number were found, fusions of microchromosomes were often detected along phylogeny (BEc; AK 1969). In Sauria, fusion/fission mechanisms and pericentric inversions were described (GORMAN and ATKINS 1967;GoRMAN et al 1967;LowE et al 1967;BuRY et al 1969;DALLAl and TALLURI 1969). As regards sex chromosomes, snakes of the family Viperidae and of most Colubridae show an evident dimorphic ZW pair in females, while this heteromorphism is not found in non-venomous species of the family Boidae (BEc; AK W. et al 1962aAK W. et al , 1962bAK W. 1965AK W. , 1966.…”