THE I.AIIELLICORX BEETLES. 941 



were from the half-dried careass of a dog. It seems, therefore, 

 that tliis spe<'i(!s sometimes has the habits of Trox, a genus with 

 which it is closely allied and in which it was placed by Say. 



Tribe VI. TROGINI. 



Oblong, cimvex. dirty-looking brown beetles, whii-h oeeiTr under 

 or about the skins and bones of i-arrion, old hides or feathers. The 

 .surface is usually roughly sculptui-ed and covered with a crust of 

 earth which is difficult to remo\'e. Prom the preceding tribe they 

 differ in form and by having the side pieces of mesothorax not 

 reaching the rounded middle e()x;i>. They possess a distinct stridu- 

 lating organ in the form of an elliptical plate with pearly reflec- 

 tions, located on the upper part of the outer face of the first ventral 

 segment, and covered by the elytra. A small oval polished space 

 on the inner surface of the elytra near the margin and about op- 

 posite the plate serves as an aid in producing the sound. All of 

 our species belong to the single genus J'ro.r. The following are the 

 principal papers treating of the North American forms : 



LcCoiite. — "Descriptions of the .species of Trox and Omorgus in- 

 habiting the United States." in Proe. Phil. Acad. Nat. Sci., 

 VII, 1S,34, 211-216. 



Horn. — "Eevision of the Species of Trox of the United States," 

 in Trans. Amer. Entom. Soc, Y, 1874, 1-12. 



XVII. Trox Fab. 17f)2. (Gr., "a gnawer.") 



Twenty-one species of this genus are recognized from the United 

 States, 14 of which have been taken in Indiana, while one other 

 perhaps occurs. Sometimes a half dozen or more species are found 

 in company in or beneath the same old skin or other remains of 

 carrion. Unless cleaned of their usual encrusted coat of dirt, the 

 specimens are very difficult to classify. 



KEY TO THE IND1.\N.V SPECIES OF TROX. 



a. Scutellum spear-shaped, i. e., nan-owed strongly near the base, its sides 

 at middle nngulate: larger species, V2 or more mm. 

 6. Elytra with rows of tubercles very distinct and tomentose, or cov- 

 ered with fine hairs. 

 c. First joint of anteniuB with dark brown hairs; clnb dark. 



1777. SCABROSUS. 



re. First joint of antennte with reddish-brown hairs; club reddish- 

 brown or ash-^'ray. 

 (/. Elytral tubercles round, tlieir entire surface tomentose. 



1778. MONACHUS. 



