THE CANADIAN ENTOMOLOGIST. 23 



remains only the difference in sculpture and the more or less distinct con- 

 cave front. The last abdominal segment of the females in all of ou^ 

 species is variable, hardly two specimens of the same species are exactly 

 alike, some have the apex subacute, others obtusely truncate, the ventral 

 surface may or may not be carinate. 



P. a?igulosa, Duv., which was overlooked by Mr. Fall in his table, 

 has a peculiar male character, consisting of a densely-punctured and 

 densely-pubescent oval spot on the first abdominal segment at middle, 

 and is the only species (except Califoniica ?) which has the last segment 

 simple, without lobe-like prolongation at middle. The species can be 

 further distinguished from the rest of our species by the distinct rows of 

 large rounded punctures on the elytra and the strongly-angulated thorax. 



The description o{ P. obtusa, Lee.,* tits angulosa better than velasco; 

 the finding of it in Philadelphia was undoubtedly accidental. Based on 

 the characters mentioned above, the following synoptic table for our North 

 American species of Polycesta is presented below : 



First ventral suture at sides strongly arcuated i. 



First ventral suture straight throughout , 3. 



1. Thorax with broad median and smaller lateral impressions, sculpture 



of elytral intervals punctate, and more or less coarsely rugose, apex 

 of last ventral of male produced at middle into a lobe-like projection, 



first ventral without pubescent spot 2. 



Thorax with broad median, but without lateral impressions, elytra with 

 well-defined rows of relatively large punctures, apex of last ventral 

 of male not produced at middle, but first ventral segment wirh a 

 densely-punctured and densely-pubescent oval spot at 

 middle , a?iguiosa. 



2. Front flat near the clypeal region, the punctuation of elytral intervals 



more evident, not coarsely transversely confluent Californica. 



Front concave near the clypeal region, sculpture of elytral intervals 

 coarsely transversely confluent elata 



3. Elytral stride deeply impressed and somewhat coarsely punctate, all the 



intervals more or less distinctly costate, last ventral of male at apex 



prolonged at middle into a lobe-like projection velasco. 



Elytral stria; not impressed, only the alternate intervals costate, the 

 intercostal space coarsely and transversely confluently punctate ; 

 last ventral of male at apex produced at middle .' . ArizoJiica- 



*Proc. Acad. Nat. Sciences, Phil., 1858, p. 68, 



