HETEROMEROUS GROUND BEETLES. 123 



and are foiiiid in rotten wooil. Tlie perfect insects are sometimes fonnd 

 upon the j,aound. They are usnally of a medium size. The following 

 are the principal genera : 



A. Lateral anil ant wior margins of tlio front continnous ; body oval ; sides of the breast beneath, often 



striated lon-itudiiiiiUy UELOrs, 1'4 Hp. 



A A. Lateral luarfriii of the front elevated, obliquo, and abbreviated. 



B. Body elongated '. Sthoxoyuim, 2. 



BB. Body very convex MniiACUMiiA. 1. 



Siil.-faniily TEXEBRIONIDES. Darkling beetles. 



Founded upon tlie genus Tenebrio, of Linuaius, a name derived from 

 the Latin tenebne, meaning tiarlaic.ss, and given to 

 these insects on account of their universally black 

 color. The family is very extensive, but, as former- 

 ly remarked, the great majority of N. American 

 species inhabit the western slope of the coutineut, 

 but some species are found in great abundance upon 

 the arid plains which extend eastward from the 

 base of the Kocky mountains. The typical and most 

 common species is the Tenehrio moUtor, a plain black 



tkmukio uivscuui-^ Fab.: v^eetlc, six-tciiths of ail iiu;h in length, whose hard, 



— fl, larva; b, pupa; c, beetle; "^ >■ i ;-> 7 ' 



dautoniia of larva: <-, max- ^^.y^x-colored larva is oftcu fouiul upou the Hoor 



ilia; /.labium; g, terminal • 



segment «howiug the dual ^yi^^jr^. oralu and uical are stored. Most of these iu- 



proleg tuUy extended, ot c> 



same— after raiey. sccts are fouTul Oil tlic gi'ouud, but somc live under 



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

 principal genera : * 



A. Ventral segmeiit.s entirely horny ; tarsi .sjiiuous beneath. 



B. Middle coxie without trocliaiitins ZoruERUS. 



B B. Middle coxa' with di.stinct trochaiitins. 



C. Tlunax transversal, its hind angh s prominent and embracing the base of the elytra AsinA. 



C C. Thorax heart-.shaped. its hind angles not prolonged PelecyI'HOKUS. 



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



D. Elytra embracing widely the sides of the abdomen ; tarsi bristly beneath.. BlaP8. Eleodes. 

 D D. Elytra not embracing widely the side.i of the abdomen. 



E. Eyes divided in two by the margin of the head : tarsi bristly beneath Blapstinus. 



£ E. Eyes not divided. 



r. Tarsi with a silky golden pube.scence beneath Uris. 



F F. Tarsi with coarse pulnscenco TENF.nitlO. 



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

 ticularly to the uumerous species of this sub-family. 



Subfamily ULOMIDES. 



This sul) family includes a small number of heteromerous lieetles, 

 which are closely allied to the Tenebrionides 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 tibiiv are more or less dila- 

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



