487] LARVAL TREMATODES—CORT 41 



intesinal ceca contained the granules and their regular spaces described 

 for Cercaria trivolvis. 



Only the main branches of the excretory system could be traced. 

 The crura were packed very full of concretions and the bladder was 

 narrow. 



Since this species was only studied alive the anlage of the repro- 

 ductive system could not be distinguished. 



In comparison with the large numbers of adult Echinostomes known 

 the descriptions of but few larval forms are to be found in the literature. 

 Cercaria rubra differs markedly from all of these in the number and 

 arrangement of the oral spines. Cercaria trivolvis on the other hand 

 agrees very closely with Cercaria echinata von Siebold. This form is 

 not sufficiently described to make a detailed comparison possible. Liihe 

 (1909:188) gives to it thirty-seven spines of equal size in the crown, 

 altho the earlier writers counted only thirty-six. The intestine of the 

 redia is shorter in Cercaria echinata than in Cercaria trivolvis, and the 

 size of the oral sucker in comparison to the acetabulum is less in the 

 former than in the latter species. 



A number of suggestions have been made in regard to the adults 

 corresponding to the European species of echinostome cercariae. None 

 of these proposed relationships have been proved by experiments. Liihe 

 (1909:65) recently made the following statement in regard to this 

 group: 



"von den bisher mit Namen unterschiedenen Cercarien (samtlich 

 aus Susswasserschnecken) ist noch keine mit volliger Sicherheit auf 

 eine bestimmte Art zu beziehen." 



In England two echinostome cercariae have been assigned to adults 

 on the basis of morphological comparisons. The cercariae were not 

 given special names; the adults are Echinostomum leptosomum Creplin 

 by Lebour (1907:447-451) and Echinostomum secundum Nicoll by 

 Nicoll (1906:517-518). 



None of the adult echinostomes from North America agree in the 

 number and arrangement of the anterior spines with the two cercariae 

 described above. 



The following form, for which I propose the name Cercaria reflexae, 

 and which was found in, some of the specimens of Lymnaea reflexo from 

 Chicago, 111., will be treated as an appendix to the Echinostome cercariae. 

 The livers of the snails infected with Cercaria reflexae were packed with 

 rediae in various stages of development of which the greatest numbers 

 were large and full of numerous mature cercariae. Sections of the liver 

 showed that but very few cercariae were free in its tissues but large 



