INHABITING NORTH AMERICA. 91 



Very closely allied to the preceding, is less common, and 

 is distinct by the punctures of the thorax, by tlie less abrupt 

 posterior termination of that pait, and by the consequent 

 less obtuse form of the angles. 



3. T. *7'upestris. Head black; thorax dark rufous, punctured 

 at base, posterior angles not rounded, beneatli black ; feet 

 testaceous. 



Length nearly one-fifth of an inch. 



Body glabrous, beneath black. 



Head black ; antennce brown ; base and palpi testaceous ; 

 nasus and labriim deep piceous- 



Thorax deep biackisli rufous, gradually a little narrowed 

 from before the middle to the hind angles, wiiich are 

 slightly angulated, the edge very slightly excurved at the 

 hind angles. 



Elytra with impunctured strise, disk l)lackish, margin and su- 

 ture dark rufous ; pectus piceous-black ; sternum black ; 

 feet testaceous ; postpectus and abdomen black. 



Far. a. Length less than one-tenth of an inch. 

 Strongly resembles the two preceding species, l)ut is sufll- 



ciently distinct by tiie form of the posterior thoracic angles. 

 It is highly probable that far. a. is in reality a distinct 



species. 



Family HI. Hydrocanthaui. 



Genus Dytiscus. Lin. iMtr. 



AntennfP longer than the head, setaceous ; scutel distinct ; 

 three basal joints of the anterior tarsi, in the male, dilated, 

 patelliform ; palpi filiform. 



Species. 



1. D. */;n&7-/o/fl/?/.9 attenuated before, blarkish-green above ; 

 thorax and elytra yellowish on the outer margin, the lat 

 ter with three sf>iies of punctures. 



