Nos. IAND2.] COTYLASPIS INSIGNIS. 5 



ists in U. edcntuhis, so that the kidney is equally accessible there, 

 yet Cotylaspis has not been found in Chautauqua Lake in U. 

 edentiilus. 



Moreover in other localities this discrimination is not made by 

 the fluke. Thus M. A. Kelley, '99, reports observations made in 

 Pennsylvania, Illinois, and Iowa, in all of which states he found 

 Cotylaspis present in several different species of Unio, though he 

 reports Anodonta as being most frequented. 



Not only does Kelley report a much larger list of hosts for the 

 animal but he reports a much greater number of parasites per host 

 than is generally found in the mussels of Lake Chautauqua. The 

 maximum number which I found was twenty- four, and this is far 

 in excess of the average number, while the maximum found by 

 Kelley is thirty-eight, and he cites a case of Anodonta corpulenta 

 in which Kofoid found ninety-two Cotylaspis in a single mussel. 

 This far exceeds the numbers for the Chautauqua Anodontas, 

 where however nearly every one is parasitized in some degree. 

 In only two cases were the flukes entirely absent. In a few in- 

 stances I found only one or two, but the number commonly ranges 

 from four to eight or ten, though it varies somewhat with the 

 kind of bottom inhabited by the host. 



A count made in three different situations gave the following 

 results : 



Bottom of clean, hard) ^^aj^. ..^ a •[ c ^ ^ \ ^ 



J ' > 32 Anodontas, 113 liukes, av. of 3.5 per host. 



^wl°.H= .?-,A JT^'']^^ Anodontas, 432 flukes, av. of S per host, 

 weeds and mud. ) ' ^"^ ' -^ ^ 



Thick o°oz/ m^ud." ^'}^' Anodontas, 96 flukes, av. of 8.7 per host. 



The last of these situations is especially interesting. It is at 

 the mouth of a drain, and the mud there is very fine grained. 

 The hosts are of large size, and their shells almost entirely desti- 

 tute of epidermis, and externally are white and pearly. 



These facts indicate a correlation between the muddiness of the 

 water and the number of flukes present in a given host. The mud- 

 diness seems due to organic matter, and the implication is that 

 this furnishes food for a greater number of the flukes. The age 

 of the host is not closely correlated with the number of Cotylaspis 

 if at all. To test this point fifty Anodontas from a stony, weedy 



