Dec, I9I2.] Fall: North American Collops. 251 



Elytra dark blue, green or blackish, unicolorous except occasionally for a narrow 

 pale edge at the middle of the lateral or sutural margin of the elytra. 



Group A. 



Elytra each with a broad longitudinal dark blue or greenish vitta usually more 

 or less narrowed at basal third, the sutural, apical and lateral margins as a 

 rule more or less completely pale Group B. 



Elytra rufous, each with a dark blue or green basal and subapical spot of vari- 

 able size, sometimes longitudinally confluent Group C. 



Group A. 



With the exception of suhlimhatus the species tabulated below 

 have the elytra completely unicolorous or virtually so. Suhlimhatus 

 is included because of its relation to tricolor, of which indeed it may 

 be no more than a variety. In tricolor the middle of the external 

 lateral edge of the elytra is often rufous or rufescent, and in suh- 

 limhatus this is more marked and affects also the sutural margin for 

 a greater or less distance. Necopinus is included here to cover cer- 

 tain forms with nearly unicolored elytra but with the middle of the 

 sutural and lateral margins faintly rufous ; the species however 

 belongs more properly to the next group. 



Humeri small, elytra expanded posteriorly, wings rudimentary ; elytra coarsely 



densely punctate, shining cribrosus. 



Humeri larger, wings well developed, elytra much less coarsely punctate (ex- 

 cept punctatus and nigritus). 

 Prothorax reddish yellow, immaculate or with at most a small central spot 

 in some examples of punctatus and parfus. 

 Prothorax small, not or but little more than half as wide as the elytra, 

 which are narrow at the humeri and strongly expanded posteriorly ; 



femora black, tibiae and tarsi rufous parz'us. 



Prothorax larger, distinctly more than half as wide as the elytra. 



Basal joint of antennae {^) without dentiform prominence, though 

 evidently angulate in punctatus and nigritus. 

 Legs black. 



Elytra rather strongly widened posteriorly, punctuation 

 fine, abdomen entirely or in part red. 

 Basal antennal joint (c^) elongate triangular, J4 or 



5^ longer than wide vicarius. 



Basal antennal joint of j^ broadly triangular, nearly 

 or quite as wide as long. 

 Elytral suture not or but feebly rufous at 



middle tricolor. 



Elytral suture and side margin in part rufous. 



sublimbatus. 



