1 86 MEMOIRS ON THE COLEOPTERA 



Placusa Erichs. 



The body in this genus is relatively broad and strongly depressed, 

 with obscure coloration as a rule, but in some forms, such as the 

 European infima Er., it becomes very sensibly convex; the male 

 sexual characters at the abdominal apex are generally as pronounced 

 as those of Gyrophcena. There are numerous species belonging to 

 the fauna of North America in addition to tacomcz Csy., from 

 Washington State; the four following have the prothorax fully as 

 wide as the base of the elytra or wider as in tacomce and complanata: 



Placusa frosti n. sp. Depressed, blacki h-piceous, the head and ab- 

 domen deeper black, the elytra feebly pallescent, the legs pale; surface 

 dull and finely, densely, asperately punctate, less densely but asperately 

 though gradually very finely, sparsely and smoothly so posteriorly 

 on the more shining abdomen; pubescence obscure, very short, loosely 

 fimbriate along the tergitical apices; head small, transverse, not three- 

 fifths as wide as the prothorax, the eyes moderate, not very convex; 

 antennae blackish, short, rather slender, gradually though very moder- 

 ately incrassate, the third joint shorter than the second, the fourth very 

 little, the tenth fully four-fifths, wider than long, the last but little longer 

 than wide, very obtuse at tip, as long as the two preceding; prothorax 

 fully twice as wide as long, the sides rounded, gradually more converging 

 anteriorly, widest behind the middle, the base rounded, the apex truncate; 

 surface with a large, broad and very shallow indentation medially, 

 not extending much before the middle; elytra transverse, with feebly 

 diverging sides, at base distinctly narrower than the prothorax, at apex 

 as wide as the latter, the suture two-fifths longer; abdomen long, gradu- 

 ally and moderately tapering, with straight sides, at base slightly nar- 

 rower than the elytra, the sixth tergite (cf ) with a very long slender 

 and feebly arcuate, inwardly oblique, porrect spine at each side of the 

 apex, the median part of the surface at apex tumid and gradually flexed 

 upward, forming a strong dorsal lobe, with its elevated tip narrowly 

 truncate. Length 1.8-2.25 rnm.; width 0.5-0.65 mm. Massachusetts 

 (Framingham), C. A. Frost. Found in Scolytid galleries. 



Belongs to the complanata group, but differs much from that 

 species in its shorter elytra, long and nearly straight sides of the 

 posteriorly much less punctate abdomen, very much smaller head 

 and in numerous other characters; it is more nearly allied to ta- 

 comce, differing in its much smaller head, less punctate abdomen, 

 and, most decidedly, in the nature of the male sexual characters. 



Placusa arizonica n. sp. Narrower, depressed, dull, finely and densely, 

 asperulately punctate, the abdomen more finely and sparsely so and 

 rather strongly shining; color piceous, the entire abdomen paler, the 

 legs pale; pubescence very short and inconspicuous; head transverse, 



