1991 Volume 56 Issue 4 Pages 503-509
Chromosomes were counted in the preparations of gonad tissues from the two species Bellamya unicolor and Lanistes bolteni collected from different localities around Qena City in Upper Egypt. A basic diploid chromosome number of 18 and 26 were presented in Bellamya unicolor and Lanistes bolteni, respectively. The karyotype of Bellamya unicolor consists of: five metacentric pairs, two submetacentric pairs and two subtelocentric pairs, while the karyotype of Lanistes bolteni consists of: eight metacentric pairs two subtelocentric pairs and three telocentric pairs. Shell measurements for these two species are also described in details in this paper. These results are reported for the first time in Egypt.