NORTH AMERICAN COLEOPTERA. 219 



Thorax distinctly wider at base; abdomen riifo testaceous, legs entirely 



pale 19. polita. 



Thoracic impression almost entirely obliterated, thorax wider at base, 



elytra sparsely punctate, color violaceous 21. opuleuta. 



Head and thorax reddish yellow; elytra blue. 

 Thoracic impression rather feeble; elytra not shining. ..22. floridaiia. 

 Thoracic impression deep and entire ; elytra rather brilliantly metallic. 



23. Burge^^si. 



13. — Form rather broadly oval; thoracic impression almost obliterated; body 



beneath brown : legs, except at base, black ; elytra smooth. ..24. rufa. 



1. H. biinarginata Say. — Oblong, subparallel, above blue, or slightly 

 bronzed, usually moderately shining, sometimes subopaque. Antennae half as 

 long as the body, piceous, joints 2-3-4 gradually increasing in length. Head 

 feebly shining, frontal carina obtuse, tubercles usually well marked, a few punc- 

 tures extending across the head above the tubercles and near the eyes. Thorax 

 one-half wider than long, slightly narrower in front, sides feebly arcuate, the 

 margin very narrow, disc moderately convex, the ante-basal transverse depres- 

 sion rather deep, slightly sinuous at middle, reaching the sides and joining the 

 marginal depression, surface distinctly alutaceous, sparsely punctate, punctures 

 more distinct near the apex and front angles. Elytra distinctly wider at base 

 than the thorax, humeri distinct, umbone moderately prominent and with a 

 slight depression within it, a prominent lateral plica begins at the umbone ex- 

 tends parallel with the margin, curves toward the suture near the apex, surface 

 alutaceous, the punctures fine and indistinct, not closely placed. Body beneath 

 and legs blue-black, shining, abdomen sparsely, indistinctly punctate. Length 

 .20— .24 inch. ; 5—6 mm. 



A.S might be expected, an insect distributed over such a wide ex- 

 tent of country exhibits some variation. The color is usually a 

 moderately bright cobalt-blue, but in the mountainous regions of 

 California specimens with a bronzed surface are quite common. 

 While the surface is usually shining, specimens are occasionally seen, 

 especially from Texas, with the surface subopaque. The ante-basal 

 thoracic groove may vary in depth, but is always entire. The lateral 

 plica, while usually prominent, is sometimes feebly so, in the former 

 case reaching, by incurving, nearly to the suture, and in the latter 

 scarcely curved at all. In some feebly developed individuals from 

 the vicinity of San Francisco the plica is almost entirely obliterated 

 and without the abundance of other specimens would be difficult to 

 identify. The lateral plica will enable this species to be separated 

 from all the others in our fauna. 



Mr. D. W. Coquillett, of Los Angeles, informs me that this species 

 in all stages feeds on the leaves of Alder {Abivs). 



