Coleopterological Notices, V. 563 



Group IX. 

 Small species resembling lucidulus; anterior tibiae strongly tridentate ; sides of 

 the protliorax fimbriate. 

 Punctures of the elytra extending, near the suture, to basal fourth. 



propeusiis 



Punctures of the elytra not extending much within basal third, very small 



and sparse servilis 



Group II of Dr. Horn cannot remain as ori<rinally proposed, and 

 in reality comprises only Gnathoncus rotundatus. The other three 

 species are widely discordant ; hehremsi belongs to group lY, and 

 is probably not different from pectoralis, in which species the pro- 

 sternal striae display a tendency to unite in front in some specimens, 

 for, in laramiensis, there are examples having the two striae paral- 

 lel, convergent in front, or shorter and completely united. Plani- 

 sternus and rugipennis are aberrant types, each possibly requiring 

 a special group. 



The four species now placed at the end of group IX, belong to 

 Pachylopus as extended by Marseul, and the genus is apparently 

 valid. 



S» Obsidianus* — Oval, strongly convex, highly polished, black, the tibiae 

 and tarsi rufescent. Head finely evenly and sparsely punctate, with a larger 

 median puncture near the base; transverse frontal stria fine but distinct, 

 widely interrupted at the base of the clypeus. Prothorax fully twice as wide 

 as long, the sides distinctly convergent and feebly arcuate from the base, 

 becoming strongly convergent and arcuate anteriorly ; marginal stria distinct ; 

 disk subimpunctate except abruptly and coarsely so along the basal margin 

 and more gradually coarsely and closely at the sides, the punctures much 

 finer toward base. Elytra at basal third distinctly wider than the prothorax, 

 one-half longer ; sides broadly arcuate ; marginal stria on the flank, distinct, 

 gradually ascending toward base and confused with the outer subhumeral ; 

 inner subhumeral completely obsolete ; oblique humeral fine, distinct, straight, 

 extending to basal third ; dorsals coarse and very coarsely punctate, subequal, 

 extending distinctly behind the middle, the first not extending beyond apical 

 third, the fourth broadly arcuate at base, joining the deep entire and punctate 

 sutural ; punctures coarse, deep, moderately close in apical two-thirds near 

 the suture and apical third at the first dorsal, not extending laterally beyond 

 the latter. Propygidium densely punctate, the punctures gradually becoming 

 very coarse posteriorly ; pygidium closely punctate, finely so toward apex. 

 Prosternal striae long, coarse, deep, gradually convergent anteriorly and 

 almost confluent just behind the apical margin ; surface convex. Anterior 

 tibiae stroiigly arcuate externally in apical half, finely pleuridenticulate. 

 Length 3.5 mm. ; width 2.6 mm. 



