144 RESEARCHES IN HEI.MINTHOI.Of'.V AND I'ARASITOLOGY. 



pouch-like stomach, black in hue, extending two-thirds the length 

 of the body. Body cavit}^ distended with cercariae in various stages 

 of development. Cercaria white ; with a compressed, ovoid body 

 emarginate behind ; tail cylindro-conical, pointed, as long or longer 

 than the body, often constricted so as to appear more or less monili- 

 form. Ej^es two, black, with an intermediate black pigment spot 

 looking like a third eye, and a number of smaller pigment spots 

 scattered in the vicinit}' of the eyes. Acetabulum. Pharynx glob- 

 ular ; intestine bipartite. A distinct pore situated ventrally near 

 the root of the tail. 



Length of sporocysts from 3-4ths to i mm. Length of cercariae 

 Y-2, mm. 



The sporocyst is quite active, elongating and shortening ; retract- 

 ing and projecting the pharynx. It also exhibits strong peristaltic 

 movements, in which the body becomes constricted tightly just back 

 of the pharynx or in any position beyond. The contraction grad- 

 ually extending backward and dividing the body cavity into two 

 compartments, the cercariae are suddenly slipped through the con- 

 striction, one after the other from the posterior to the anterior com- 

 partment. The movements of the cercariae, liberated from the 

 sporocyst, consist mainly in elongation and narrowing and shorten- 

 ing with widening of the body. Elongation of the body causes it 

 to exceed the length of the tail. At times the lateral extremities 

 of the posterior emargination of the body are prolonged into short 

 conical appendages. 



This fluke occurs abundanth' beneath the musular tegument, 

 among the lobes of the liver, and folds of the intestines of Planorbis 

 parvus. Upwards of fifty of the sporocysts distended with cercariae 

 have been removed from a single Planorbis. 



Distoma {Gym.7ioa'p/iala) Ascoidca. Sporocyst white. Head dis- 

 tinct from the bodj', campanulate, varying in the proportion of 

 length to breadth, according to the degree of contraction. Body 

 cylindroid, with a pair of lateral conical appendages, beyond which 

 it extends as a cylindro-conical tail-like prolongation. Pharynx 

 globular, encircled with six equidistant organs (undetermined in 

 character, probably teeth? or perhaps ganglia). Stomach a flask- 

 like pouch extending but a short distance from the head into the 

 bod}' cavity, and not reaching the middle of the latter, even in its 

 most shortened condition ; bright brown in color. Body cavity dis- 

 tended with numerous cercariae ; the immature ones occupying the 

 tail-like prolongation. An orifice at the extremity of a blunt conical 

 snout communicates with the body cavity just back of the head. 



