34 ENTOZOA FOUND IN MAN. 



found in the digestive tube, in the respiratory cavi- 

 ties, and in the biliary passages of vertebrated 

 animals. They are more frequently found in aquatic 

 animals or those which live in the vicinity of water 

 than in animals which hve in dry places ; as may be 

 observed in the amphibia amongst reptiles, in the 

 wading and web-footed genera amongst birds, and in 

 fishes amongst the vertebrata. 



The distoma do not appear to be limited to 

 certain parts of the globe, and they are also less 

 exclusively peculiar to certain animals than is the 

 case with other entozoa. 



The distoma present four different forms which 

 are distinguished by the number and by the position 

 of the suckers, and which constitute four genera. 

 Two of these are characterised by the existence of a 

 single sucker, and are the monostomum and amphis- 

 tomum of E-udolphi. In the monostomum the sucker 

 is situated at the anterior extremity, ia the amphis- 

 tomum at the posterior extremity. The two other 

 genera, the distomum and the holostomum, have an 

 anterior buccal sucker and an abdominal sucker. 



Genus Monostomum. 



This genus comprises several species which are 

 found in the intestines or other organs of birds, 

 reptiles, and fishes. 



The only species which has been observed in man 

 is the Monostomum lentis, a very minute parasite 

 found by Nordmann, in the lens of a patient who 

 was afiected with cataract. 



