146 ENTOZOA. 



then recently ascertained, a more particular account of wMcli, com- 

 bined with the results of my own inquiries, was subsequently sub- 

 mitted to the consideration of the members of the Zoological 

 Society of London, and afterwards published in their Proceedings. 

 In the present work I propose to enter upon the consideration of 

 all the human parasites somewhat after the same method as the one 

 then adopted, dwelling, however, in this case, not only at a much 

 greater length on the structure and economy of nearly all the para- 

 sites there mentioned, but also describing with considerable detail 

 those particular species which more or less frequently produce fatal 

 results. 



In the subjoined list of the human entozoa, I only record those 

 which are perfectly distinct forms, and therefore, for the most part, 

 good species. Many parasites which were at first supposed to be 

 distinct will be found iu the synonyma placed at the head of each 

 article where the species is separately considered. The larvge are 

 noticed under the titles of the adults to which they are either known 

 or presumed to be respectively referable. This method is followed 

 even in cases where the adult condition is not known to occur in 

 the human body or in any other "host:" thus, for example, the 

 Cysticercus acanthotrias is placed under Tcenia acanthotrias, although 

 the mature tapeworm at present remains unknown. The various 

 specie will be found described in the following order : — 



HUMAN ENTOZOA. 



1. Fasciola hepatica, Linneus. 



2. Distoma lanceolatwm, Mehlis. 



3. Distoma opMhalmobium, Diesing. 



4. Distoma crassum. Busk. 



5. Distoma heteropJiyes, Siebold. 



6. BiTharzia heBmatohia, Cobbold. 



7. Testrastoma renale, DeUe Chiaje. 



8. Hexathyridium, pinguicola, Treutler. 



9. Hexathyridium venarvm, Treutler. 



