AILMENTS AND DISEASES 



ally the carplike fishes, often in such numbers as to 

 cause the death of both young and mature fishes, 

 especially the very young. Other species which have 

 freshwater fishes as hosts are G. carassiusculus, G. 

 cochlea and G. tenuis. These parasites also attack the 

 surface of fishes and amphibia and burrow into the skin 

 under the scales, where they produce inflammations and 

 raw surfaces which form seats for fungi and ultimately 

 FIG. 80. GyroJactyim degani. causc the death of the fishes. Gyrodactylida are 

 among the most frequent parasites which affect the 

 goldfish in the aquarium and breeding tank. 

 The North American Aspidocotylea and Malacocotylea consist of 

 Faramphistomidte, Fasciolid^e, Schistosomidie, Holostomida, Gasterostomid^e, 

 Didymozoonidie and Monostomidie; divided into 35 sub-families, 134 genera 

 and 22 related genera, parasitic in Vertebrates, of which the following 

 species are found in freshwater fishes and amphibia of the United States: — 



A Trematod Parasite. 

 Greatly enlarged. 



147 



