274 ENTOMOLOGICAL NE\VS [Nov., '22 



respects, however, this species seems to agree with our 

 American species. 



In the pygidium and propygidium I can find no other specific- 

 characters than the variation in punctation and hairiness. These 

 variations, however, seem to be constant and offer a ready 

 means of separating the species. I have carefully examined a 

 series of eighteen specimens of Hetaeriits selus Fall, and over 

 twenty-five of Hetaerius tristriatus Horn, for sexual char- 

 acters, but have not been able to detect any here or elsewhere. 

 Tn the prosternum we encounter one of the most valuable 

 series of variations for specific separation as well as generic 

 division. There are two types of prosternum, separating the 

 genus into two well defined groups, one I shall call the sub- 

 cylindrical, the other the depressed type. In the first or sub- 

 cylindrical type, a ventral view of the prosternum' shows a sort 

 of vase form with its base between the coxae and its bulbous 

 tip at the cephalic extremity. The mesothoracic contact is 

 emarginate and extended into two rounded angular lobes 

 around the ends of the coxae. Between the coxae the sides are 

 suddenly convergent, followed by a gradual divergence to a 

 maximum at about the middle of the prosternum, at which 

 point there is a convergence to a neck-like constriction, then 

 an expansion to a bulbous extremity which has a pit-like de- 

 pression on its end. The cephalic portion of this prosternal 

 ridge is subcylindrical in bas-relief, growing less so at the 

 middle and becoming flat between the coxae. The second or 

 depressed type is the same in general plan as the above except 

 that there is a varying slope away from the summit of the 

 prosternal ridge instead of an abrupt drop as in the former. 

 The mesothoracic contact is margined in both types and the 

 extension of the bordering carina along the flattened surface 

 of the ridge produces the margined area. 



In the head we find some differences both in shape and 

 punctuation, but owing to its retraction, the front is the part 

 most often made use of. The antennae also are difficult to 

 see and for this reason have probably not been mentioned in 

 descriptions. 



The legs differ considerably in their proportions but as it 

 requires special manipulation to measure them, I have tried 



