8 University of Michigan 



XicoU found Ccrcaria ordinata in thin cysts. This species 

 occurs in extremely dehcate cysts in the fat bodies but no cysts 

 are produced in other parts of the host. Where cysts occur 

 they appear to be made up of about one layer of flattened con- 

 nective tissue cells differing from the surrounding fat cells 

 only through the loss of fat globules. Even in the fat bodies 

 the formation of definite cysts is rare. 



The method of entrance of this cercaria into the host is 

 unknown but since Tharnnophis marciana feeds largely on tad- 

 poles when they are available it seems likely that the cercaria 

 are taken with the tadpoles which may be a still earlier host. 

 \\ ork upon the preserved hosts has not revealed the method by 

 which the cercaria get into the lymph spaces. Dr. W. W. Cort 

 in a letter to the writer dated January lO, 191 5, states, "Tre- 

 matodes seem to be able to worm their way through tissue. I 

 think there is no doubt that larval forms in muscles usually 

 come by way of the alimentary canal. I have seen holostome 

 larvae pushing their way through the muscles of the tadpole." 

 Since these cercaria are provided with a close armature of 

 fine spines they should find no difficulty in penetrating the 

 tissues of their host. Why they congregate in the lymph 

 spaces of the tail rather than in the body cavity is not known. 

 Nor is it known why they collect in great numbers in the 

 spaces so near to the scutes of the tail. 



Cercaria vegrandis, new species. 



The second species of larval trematode, Cercaria vegrandis 

 n. sp., was found occurring in small numbers in cysts in the 

 fat bodies only of one specimen of Tharnnophis marciana from 

 a tank or pond in Fort Davis and of one specimen of T. cques 

 from Limpia canyon. In the first mentioned host it occurred 



