STUDIES IN THE AMERICAN BUPRESTIDiE II7 



pronotum uniformly impressed or sulcate along the middle. The 

 labrum is more chitinous and metallic in its basal parts, but, aside 

 from this, there is very little in the structure of the sclerites or organs 

 of the body to distinguish it as a separate group. The complete 

 absence of true elytral striae and the substitution therefor of a few 

 longitudinal ribs, separated by wide and uniformly punctured or 

 rugulose intervales, is evidently a result of advanced evolution through 

 Buprestid species of the langi type, the latter having evenly and closely 

 sulcate elytra, with the sulci densely and confusedly punctato-rugose; 

 and the impressed median line of the pronotum, incipiently evident 

 in those forms, becomes here still more developed as an external 

 feature. We have only to imagine the coarse sulci of langi to be 

 greatly expanded, coincidently with the suppression of the alternate 

 ridges, to evolve the typical forms of this group, traceable indeed 

 in intermediate stages through such species as adjecta, brevis and 

 intricata. But the true striation of typical Buprestis has so completely 

 disappeared that the group would seem to require separation as a 

 subgenus, and, if the intermediate forms above mentioned, which are 

 however much more closely related to typical Cypriacis, as exemplified 

 in lauta, than to any species of true Buprestis, were to become extinct, 

 the differences would certainly be of full generic import. The species 

 are generally of vivid green or bluish-green metallic coloration, with 

 abruptly cupreous elytral side margins as a rule, though occasionally 

 dull coppery-brown throughout. Those known thus far may be 

 characterized as follows: — 



Elytral costte convex, their summits polished and impunctate. Pacific 

 regions to Lake Superior 2 



Elytral costae flat, punctured. Atlantic regions 13 



2 — Intervales between the costae each with a feeble secondary ridge, that 

 between the sutural ridge and the first normal costa strong and sub- 

 similar to the latter 3 



Intervales uniformly concave, densely and uniformly sculptured throughout . 5 



3 — Elytral suture not at all cupreous. Body short, stout and convex, mod- 

 erately shining, green, the head, lateral and apical parts of the prono- 

 tum and side margins of the elytra cupreous; remainder of the elytra, 

 less noticeable sublaterally and basally, with dark purplish-blue reflec- 

 tion; under surface throughout of a bright metallic magenta; head 

 strongly but rather sparsely punctate, more finely, densely so basally; 

 eyes moderate, the antennae slender, dark piceous; prothorax strongly 



