THE FEATHER-WINGED BEETLES. 485 



roanded, widely separated by the broadly dilated second ventral 

 segment; tarsi three-jointed. 



Several species of the genus Micropeplus have a range which 

 may include Indiana. Thej have the abdomen margined and head, 

 thorax and elytra costate, much as in Ghjptoina. M. cribatus Lee, 

 blackish with the next to last segment of abdomen carinate above ; 

 the costae of elytra sinuate, intervals coarsely punctured, length 2 

 mm., has been taken near Cincinnati. M. iesserula Curtis, sixth 

 segment not carinate, body black, shining, length 1.5-2 mm., is a 

 boreal species known from ^lichigan. 



Family XII. TRICIiOPTERYUID.E. 



The FE.\THEK-^VTNGED llliETLKS. 



This is a small family of nnniitc beetles, the l;n-ges1 of which 

 scarcely exceeds a pin-head in size. They live iu rotten wood and 

 dung, on fungus covered logs and in ants' nests, and comprise the 

 smallest of known beetles. The name is derived from that of the 

 typical genus, Trirh(ij>tcr!j.r, a term meaning "hairy-winged," the 

 inner wings, when present, being long, narrow and fringed with 

 long hairs, or feather-like in appearance. 



The memljers of the fapiily have the maxilhe exposed at the base, 

 whicli is large, with two lobes, the outer one hooked; palpi 4-.jointed, 

 the last joint needle-shaped; antennas usually 11-jointed, inserted 

 on the margins of the front, the joints with whorls of long hairs, 

 joints 3 to 7 slender, S-11 thicker, forming a loose elongate club; 

 thorax with the side pieces distinct ; elytra often abbreviated ; inner 

 wings as above described; abdomen with six or seven free ventral 

 segments; front coxee subglobular, prominent, contiguous; middle 

 coxse oval, separated; hind ones transverse, more or less separated; 

 tarsi 3-jointed, the last joint with two eijual simple claws. 



Aboat 75 species, distributed among 18 genera, are known from 

 North America. Of these but S have been taken in Indiana, though 

 a number of others doubtless occur, and the genera are therefore 

 included in the key which follows : The principal and practically 

 the only reference works aj-e as follows : 



Matthews, Rev. A. — "Triehopterygia lUustrata et Descripta," 

 London, 1S72. 



l]ii(J_ — "S\ii(ipsi.s of North Aiueriean Trieli()|iteryyida'," in 

 Trans. Amer. Ent. Soc, XI, 1S84. 113-156. 



