NEW PARASITE FROM THE CRAYFISH. 



The adult stage of B. cormtta is found at Chautauqua in the 

 stomachs of black-bass, rock-bass and cat-fish or bull-heads, 

 caught near the Assembly grounds, and earlier stages are found 

 encysted in crayfish, caught near the shore just above the grounds. 

 These localities are near the head of the lake. I have not ex- 

 plored the lake in other places and cannot say how generally the 

 fluke is found in it. The crayfish is clearly the host immedi- 

 ately prior to the fish, as partly digested crayfish are present 

 in the stomachs of fishes where the cysts and the young just 

 escaped flukes are found. The infection of the crayfish is prac- 



o.lmtn 



FIG. 2. Young worm still enclosed in cyst, X I2O > ' ne shaded area was opaque, 

 and white by reflected light. 



tically universal. The flukes are always found encysted, never 

 free. They are located in the parts immediately related to the 

 reproductive system, most constantly in the muscles, especially 

 those running from the thorax to the abdomen, also in the heart 

 itself, and in the gonads. Remoter organs are not infected. 

 This mode of occurrence indicates that the infection may be 

 through the ducts of the gonads, but I have no observations to 

 decide this point. The number of cysts per individual varies 

 considerably, in one case 40 were found, distributed as follows : 

 25 in the muscles, 6 in the walls of the heart.^9 in the spermary; 

 in another case : 16 in the muscles, none in the heart or gonad ; 

 in still another a few were seen in the muscles and none in the 

 heart or gonads. The cysts vary somewhat in size and structure 

 with the season. In early July they are 0.9 mm. in diameter 

 and consist of a soft fleshy grayish enveloping portion about 0.2 



