-

The biology of reproduction of Melanopsis praemorsa L.was studied on molluscs found in Mozdouran,l00 Km north eas Mashhad , Iran. Monthly samplings were made for a year time.It was found that in that habitat.This snail lays eggs throughout the year
Among the large population from which the samples were collected and examined histologically, male, female and sterile animals were recognized. Measurinents made on shell heights, lengths of gonads and diameter of their acini showed that male snails were small in size (ave.shell height = 4.5 mm), steriles were medium in size (ave.shell height=6znm),and females were the largest individuals (ave. shell heights 8.5 mm). Examination of different stages of spermatogenesis and oogenesis and experimental work carried out in the laboratory showed no sign of parthenogenesis in this species.Amongst 576 animals examined histologically , it was noted that half of the population were steriles but , approximately one third and two third of the remainings were male and female, respectively.