BTJPRESTIDAE. 149 



The species are elongate, dull black or brown, coarsely punc- 

 tured insects, with the upper surface flattened, aud entirely desti- 

 tute of the varied colors which render the species of the two 

 previous groups so ornamental. 



I regard our species as all belonging to one genus, Crenia- 

 stochilus, although the diiferences in form of the mentum are 

 considerable ; Psilocnemus Burm. is one of these variant forms, 

 but is established on a species (P. leucosticta) unknown to me. 



True Cremastochilus, having the mentum deeply concave, and 

 incised behind, is confined to the Atlantic slope, as far as the 

 Platte River; the groups with the mentum pointed behind are 

 distributed from the Platte River to the Pacific Ocean. 



Sub-Tribe 2.— Trichiiiii. 



These insects are readily distinguished by the side pieces of 

 the mesothorax not rising so as to be visible above, and by the 

 elytra not being sinuate on the sides ; the thorax is narrower than 

 the elytra, and usually rounded on the sides, giving the insects a 

 different appearance from those of the preceding sub-tribe ; the 

 last spiracle is nearer the anterior than the posterior margin of 

 the segment in Osmoderma, about the middle in Trichius and 

 Gnorimus, and near the posterior margin in Valgus. 



No species of this sub-tribe has yet been found on the Pacific 

 slope. 



Our four genera may be thus arranged, none having the meso- 

 sternum protuberant : — 

 Posterior coxae contiguous ; 



External lobe of maxillae corneous. Osmoderma. 



External lobe of maxilla? coriaceous, lamelliform ; 

 Elytra longer than wide, thorax sinuate at base. Gnorimus. 



Elytra not longer than wide, thorax rounded at base. Trichius. 



Posterior coxae widely separated. Valgus. 



I have strong doubts whether Gnorimus should be retained as 

 distinct from Trichius. 



Fam. xxxiil— buprestidae. 



Mentum moderate, subquadrate, or triangular, sometimes 

 transverse, the anterior part in many genera membranous; 

 ligula frequently not prominent; labial palpi short, 3 jointed. 



