242 



S. VOSIIIDA : 



large, with distinct circular muscle-fibers in wall. Head subspherical. 

 Suckers oval. Neck short. Length of segments increases posteriorly ; 

 anterior segments broader than long ; middle segments quadrate ; 

 posterior segments longer than broad. Genital pores unilateral, situated 

 nearer to anterior than to posterior end of lateral segment edge. 

 Cirrus pouch longer than half the breadth of segment, antcro-dorsal in 

 position; its wall with 12-14 muscular bundles. Cirrus stout, armed 

 with short spines. Seminal vesicle dorsal to the inner end of cirrus 

 pouch. Testes dorsal to cirrus pouch. Ovary ventral in the middle of 

 segment. Vagina along ventral side of cirrus pouch. Seminal receptacle 

 between ovary and cirrus pouch. Uterus in posterior segments 

 wide, containing onchospheres. Longitudinal muscle fibers discontinuous 

 and wide apart. 



Description. 



External characters. — The worm measures 4-4Ì mm. in total 

 length. It is very slender in the anterior three-fifths of its length, 

 measuring only 0.07-0.1 mm. in breadth; much broader in the remain- 

 ing posterior parts. The head is subspherical, 0.18 0.25 mm. long, 

 O.18-0.22 mm. broad, slightly angulatcd at the four suckers. These 

 arc oval, measuring 0.1-0.2 mm. by 0.07-0. 1 mm. The rostellum, 

 when fully extended, is very long, measuring 0.3 mm. in length and 

 O.O25 mm. in thickness ; it is slightly broadened at the frontal end 

 (fig. 21). In many specimens the rostellum is half protuded, and then 

 a circle of 10 hooks, each 0.04 mm. long, is found in the rostellum, 

 sac (fig. 18). On fully protruded rostellum hooks are nowhere to be 

 seen, evidently as the result of loss (fig. 21). The rostellum sac is 

 O.18-0.25 mm. l° n S anc ' 0.06-0.09 mm. broad, showing well-developed 

 circular and longitudinal muscle fibers in the wall. 



The neck is very short. 0.08 mm. long ami 0.07 mm. broad. 

 Anterior segments 0.02-0.03 mm. long and 0.7-0. 1 mm. broad. Some 

 segments in the middle parts quadrate in shape, measuring o. 1 mm. or 



