Abstract
Anatomical examination was made on Bulinus (Bulinus) truncatus, the vector snail of the human urinary blood fluke in Libya, collected at the oases in the Fezzan area and the habitats of the snail were ecologically surveyed. The anatomical features are as follows : The radula has the arrow-headed mesocone in the lateral teeth and the right midgut gland could not be detected. Among the specimens examined was found a fair number of aphallic specimens, in which the prostate gland degenerates to take the shape of ramifying follicles and the vas deferens ends in a blind tube near the base of the spermathecal duct. The central nervous system is, in general, akin to those of other pulmonate snails in member and arrangement of the ganglia and nervous threads. A nervous thread of the left cerebral ganglion innervates the male copulatory organ and it degenerates in aphallic specimens. The vascular system is similar to those of other Basommatophorus pulmonate species. The Fezzan area is an arid desert and has scanty rainfall, hence water is supplied entirely by pumping up from wells. Water for irrigation is usually reserved in concreate cisterns and supplied through irrigation ditches to small fields. Bulinid snails are restricted in distribution in the cisterns and irrigation ditches.
