STUDIES IN THE AMERICAN BUPRESTID^ I29 



departing noticeably in structure from the corresponding parts in 

 Psiloptera and Gyascutus, as we are led to suppose from the group 

 divisions made by LeConte in his monograph of the American species 

 of the family. 



The male does not differ much from the female in superficial char- 

 acters, but the sterna are apt to be more impressed and punctate and 

 more hairy in the former, where the apex of the fifth ventral is trans- 

 versely, rectangularly emarginate as a rule, with the median part of 

 the notch briefly and broadly produced in a truncate lobe. In the 

 female the apex is more acuminate and is narrowly and deeply emargi- 

 nate, generally with a slender tooth projecting from the bottom of the 

 sinus, sometimes as far posteriorly as the lateral lobes; this tooth may, 

 however, be well developed to wholly obsolete within specific limits 

 and the sinus itself may be broader or narrower. In the male the 

 intermediate tibiae generally have on the inner side an obtuse tooth, 

 which occasionally becomes a slender erect process as in horni. The 

 coloration of the body is brassy or bronzed to dull cupreous as a rule, 

 but is sometimes deep black throughout and without metallic lustre of 

 any kind. 



The species are very numerous in subarctic North America and are 

 assignable to a considerable number of distinct groups, for the most 

 part recognized and clearly characterized by LeConte; these groups 

 may be briefly indicated as follows: — 



Presternum flattened, concave or sulcata 2 



Presternum convex 10 



2 — Prothorax not constricted basally or arcuately inflated before the 

 middle 3 



Prothorax shorter and more transverse as a rule, sinuously narrowed basally 

 behind the more or less marked anterior inflation, the pronotum gen- 

 erally more uneven in sculpture 7 



3 — Intermediate tibiae not dentate in the male though sometimes obtusely 

 swollen or subangulate within 4 



Intermediate tibiae of the male with a strong obtuse internal tooth 5 



Intermediate tibiae of the male with a slender erect serrulate process inter- 

 nally 6 



4 — Elytra obliquely and gradually narrowed posteriorly, the sides usually 

 becoming feebly sinuate before the apices, which, however, are not 

 prolonged; they are deeply sinuate and acutely bidenticulate; pronotum 

 never obviously canaliculate Group I 



