P. Manson-Bahr and N. H. Fairley 
45 
the ventral sucker. Vasa efferentia lead from each testis and unite to form 
the vesicula seminalis. This is an elongated tube which narrows anteriorly 
and passes into the vas deferens, and this in turn opens on to the exterior by 
the genital pore by means of an ejaculatory duct. 
The female schistosomes are cylindrical and thread-like, 1*5 to 2 cm. 
in length, and tapering at the anterior and posterior extremities. In breadth 
they are a quarter that of the male—0-25 mm. The body is smooth save 
towards the posterior end and on the suckers where there are papillae. They 
possess two suckers, oral and ventral. The alimentary canal is similar to that 
Text-fig. 2. Schistosomum mansoni. Adult $ and $ x 30. 
From drawings made to scale by Dr J. K. Lund. 
of the male, the caeca uniting to form a single median tube zig-zag in appear¬ 
ance. 
The reproductive organs consist of (1) an ovary, an elongated oval body 
lying anterior to the re-union of the intestinal caeca. The oviduct arises from 
its posterior end and bends forward to unite, anteriorly to the ovarv, with the 
vitelline ducts from the yolk gland. (2) The yolk glands which occupy the 
posterior part of the body, lateral to the single tube formed by the intestinal 
caeca. (3) The shell gland which also opens near the junction of the vitelline 
ducts and the oviduct. (4) The uterus which is a long tube opening on to the 
exterior at the genital pore. 
