THE FEATHER-WINGED BEETLES. 485 



rounded, widely separated by the broadly dilated second ventral 

 segment ; tarsi three-jointed. 



Several speeies of the genus MicroiH-jtlux have a range which 

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

 thorax and elytra costate, much as in (ili/plnnm. M. cribatus Lee., 

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

 the costa? of elytra sinuate, intervals coarsely punctured, length 2 

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

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

 boreal species known from Michigan. 



Family XII. TK1C1 !( )PTEKY(i 1 IKK 



THE FEATHER-WINGED BEETLES. 



This is a small family of minute beetles, the largest of which 

 scarcely exceeds a pin-head in size. They live in 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, Trlchopteryx, a term meaning "hairy-winged," the 

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

 long hairs, or feather-like in appearance. 



The members of the family have the maxilhe exposed at the base, 

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

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

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

 joints 3 to 7 slender, 8-11 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 coxa? subglobnlar. prominent, contiguous; middle 

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

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



About 75 species, distributed among IS 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 are as follows : 



Matilu'u-s, Rev. A. " Trichopterygia Illustrata et Descripta," 

 London, 1872. 



ihid. "Synopsis ol' North American Triclioplerygidti 1 ," /// 

 Trans. Amer. Ent, Soc,, XI, 1884, 113-156. 



