291] PROTEOCEPHALIDAE—LA RUE 291 



which in some cases is far different from that expected if the idea of 

 the specificity of hosts be strictly adhered to. The data on distribution 

 and food habits of the hosts have been abstracted and combined from 

 several sources, chief of which are Nitsche (1909), Leunis (1883), 

 Bridge (1904) and Boulenger (1904) in Cambridge Natural History, 

 volume VII, Jordan and Evermann (1896-1900), and Forbes and Rich- 

 ardson (1909). 



Proteocephalus amhlopUtis 

 This species is known at present only from waters which drain into 

 the St. Lawrence and the Red River of the North. Altho Professor 

 Ward examined the proper host species from the Illinois River at 

 Havana, 111., during the summer of 1909 his collections show that this 

 parasite was not present there. The reported hosts are AmhlopUtis 

 rupestris, Micropterus salmoides, M. dolomieu, and Amia calva. The 

 first three hosts have much the same distribution over eastern and cen- 

 tral North America to the Gulf of Mexico, while Amia calva occurs 

 over a somewhat more restricted area. It is abundant, however, over a 

 large part of the area in which the other hosts are found. In many 

 localities two, three, or even four of the hosts live in the same waters. 

 All four hosts are carnivorous, eating other fish and crawfish. Some of 

 them eat other food in addition. These four hosts live in the same 

 general region, frequently in the same waters, and have certain food 

 habits in common. Such are the conditions to be expected if the hosts 

 are to harbor a common parasitic species. One question remaining to 

 be solved is this: why is this species not found in the Illinois River 

 where these hosts live in large numbers? Since the Illinois River was 

 connected with the Great Lakes in the recent geological period the 

 failure to find this species in this river seems the more remarkable. 



Proteocephalus cernuae 



P. cernuae is known at present only from Prussia and from Lake 

 Balaton, Hungary. The waters of Prussia drain to the Baltic Sea while 

 those of Lake Balaton drain into the Danube and so to the Black Sea. 

 The hosts of this species are Acerina cernua and A. schraetzer. The 

 former has a wide distribution in north and central Europe and is also 

 found in the Danube. A. schraetzer is confined to the Danube and its 

 tributaries. Thus in the Danube the ranges of the two species overlap. 

 Both species are carnivorous and both take bottom fauna. Under these 

 conditions of distribution and food habits one would expect to find both 

 species harboring the same cestode species. With further study of the 

 collections this parasite will probably be found to have a much wider 

 and a continuous distribution. 



