HETEROMEEOUS GROUND -BEETLES. 123 



and are found in rotten wood. The perfect insects are sometimes found 

 upon the ground. Tliey are usually of a medium size. The following 

 are the principal genera : 



A. Lateral and anterior margins of the front continuous ; body oval ; sides of the breast beneath, often 



striated longitudinally Helops 24 sp. 



A A. Lateral margin of the front elevated, oblique, and abbreviated. 



B. Body elongated - Strongylium, 2. 



BB. Body very convex Meuacantha, 1. 



Sub-family TENEBEIO^IDES. Darkling beetUs. 



Founded upon the genus Tenebrio, of Linngeus, a name derived from 

 [Fig. 57.) the Latin tenebrce^ meaning ^arbiess, and given to 



1^j-r^^^^^^ these insects on account of their universally black 

 v!) H^/^ --'A color. Tlie family is very extensive, but, as former- 

 ^ Jl ly remarked, the great majority of N. American 

 ^B species inhabit the western slope of the continent, 

 W^ but some species are found in great abundance upon 

 |w the arid plains which extend eastward from the 

 ^ base of the Eocky mountains. The typical and most 

 f'^T >> r\ common species is the Tenebrio molitor, a plain black 

 -SirvLfb.^Sarrbe^eti'e; beetle, six-tcuths of an inch in length, whose hard, 

 i^'L'l'r*^™hibium^f'^,rteTininai wax-colorcd hirva is often found upon the floor 

 proieg"*hifiy'^ixL*dld,'^"of whcrc grain and meal are stored. Most of these in- 

 same— after Kiiey. sects are found on the ground, but some live under 

 the bark of fallen and decaying trees. The following are some of the 

 principal genera : 



A. Ventral segments entirely horny ; tarsi spinous beneath. 



B. Middle cosie without trochantius Zophehus. 



B B. Middle cox;© with distinct trochantins. 



C. Thorax transversal, its hind angles prominent and embracing the base of the elytra Asida. 



C C. Thorax heart-shaped, its hind angles not prolonged Pelecyphorus. 



A. A. Ventral segments .3 and 4 with the hind margin membranous. 



D. Elytra embracing widely the sides of the abdomen ; tarsi bristly beneath.. Blaps. Eleodes. 

 D D. Elytra not embracing widely the sides of the abdomen. 



E. Eyes divided in two by the margin of the head ; tarsi bristly beneath Blapstlsus. 



E E. Eyes not divided. 



E. Tarsi with a silky golden pubescence beneath IJpis. 



F F. Tarsi with coarse pubescence Texehkio. 



The general remarks made in describing the present tribe, apply par- 

 ticularly to the numerous species of this sub-family. 



Sub-family ULOMIDES. 



This sub family includes a small number of heteromerous beetles, 

 w^hich are closely allied to the Teuebrionides in their general characters, 

 but differ from them chiefly in their shorter and more or less perfoliate 

 antenna?, the absence of trochantins in their middle legs, and their 

 usually reddish-brown color. The anterior tibiiB are more or less dila- 

 ted, and sometimes toothed on the outer edge, and the last tarsal joint 



