UNITED STATES. 79 



gin of the anterior ones, armed behind with a large 

 acute spine. 



Rather common in forests, and frequently found 

 attached to different animals. 



8. I. *fuscous. Body fuscous, ovate, punctured ; 

 ter%um with a few black, obsolete lines, and a pro- 

 foundly indented submarginal line, posterior mar- 

 ginal impressed line none; no distinct thorax ; edge 

 rounded ; food* posterior edge rectilinear, angles not 

 prominent beyond the rectilinear edge ; eyes not vi- 

 sible ; palpi suboval, terminal joint rather longer 

 than the preceding one. 



Cabinet of the Academy, 



A common species. 



genus HYDRACHNA. Mull Lair. 



Rostrum advanced, conic ; mandibles none ; palpi 

 projecting, terminated by a moveable appendage ; 

 body subglobular ; feet natatory. 



Species. — H. ^triangularis. Body white; eyes 

 two, sanguineous ; tergu/m with a black triangular 

 spot near the eyes, posterior portion black, with a 

 white dorsal line terminating in the cloaca. 



The specimen, from which this portion of a de- 

 scription was taken, I found in Unio cariosus, in 

 which, possibly, it had adventitiously effected a 

 lodgement. 



