4 University of Michigan 



caria presenting the usual features (Fig. i). Its length is 

 about 0.42 mm. and its breadth about 0.22 mm. It is much 

 flattened dorsoventrally, oval in shape, usually narrow at the 

 anterior end and broadly rounded at the posterior end. The 

 surface of the body is covered with minute spines arranged in 

 regular longitudinal rows. The spines on the anterior end of 

 the body are a trifle longer than elsewhere. The oral sucker 

 is terminal, protrusible, in some contraction states slightly 

 sub-terminal, somewhat funnel-shaped, length exceeding the 

 breadth. It measures about 0.081 mm. long by about 0.070 

 mm. broad. Well developed muscles encircle its lower hemis- 

 phere. The acetabulum is prominent, muscular, situated about 

 the middle of the ventral surface, frequently posterior to the 

 middle but in elongated specimens slightly anterior to the 

 middle. It is almost circular and about 0.076 to 0.079 i^^""*- "^ 

 diameter. 



A prominent feature of the stained specimen is the group 

 of four large cephalic glands which lie in a row across the 

 body ventral to the intestinal bifurcations. These are ovoidal 

 or irregular organs composed each of a single cell provided 

 with a nucleus measuring about 0.0 1 mm. in diameter. A 

 large nucleolus or net-knot is a prominent feature of each 

 nucleus. The glands are arranged in two groups of two each, 

 right and left, and the ducts leading from the members of a 

 group appear to unite to form a single duct which passes for- 

 ward penetrating the tissue of the oral sucker and discharging 

 near the external opening of the latter. This apparent union 

 of the ducts is to be found in toto preparations of specimens 

 unstained or stained with carmine, eosin, orange G, or haema- 

 toxylin. Even sections stained in haematoxylin alone or in 

 contrast with cosin present this appearance. If, however, the 

 specimens be stained in toto or after sectioning with an aqueous 



