486 FAMILY XII. TRICHOPTERYGID^:. 



KEY TO INDIANA GENERA OF TRICHOPTERYGIDJE. 



</. Elytra entire. 



I. Thorax widest at base. 



c. Pygidium invisible; form oval, very convex; color dark. 



I. XOSSIDIUM. 



cc. Pygidium visible beyond the elytra ; hind angles of thorax not 

 elongate ; form elongate ; color pale. NANOSELLA. 



bb. Thorax widest before the base. 



d. Pygidium visible beyond the elytra. PTILIVM. 

 dd. Pygidium invisible. II. PTENIDIUM. 



iia. Elytra truncate. 



e. Antenna? very short, 9-jointed; eyes wanting; thorax larger than 

 elytra. Ill- LIMULODES. 



ee. Antenna? elongate, 11-jointed. 

 /. Thorax widest at the base. 



g. Abdomen with seven ventral segments. PTEHYX. 



.'///. Abdomen with six ventral segments. 



h. Hind coxa? very widely separated; mesosteruum scarcely cari- 



nate; color pale. PTINELLODKS. 



Jih. Hind coxa? moderately separated; mesosternum distinctly cari- 



nate. IV. TRTCIIOPTERYX. 



//. Thorax widest before the base. 



i. Elytra long; mesosternum carinate; color dark. V. SMICIUS. 

 ii. Elytra short ; mesosternum not carinate. 



j. Body opaque; abdomen moderate; hind coxa? with plates. 



NEPHANES. 

 jj. Body translucent; abdomen very long; color pale. 



VI. PTINELIA. 



I. NOSSIDIUM Erichs. 1845. ((jr.. " nest + formed.") 

 Small oval, convex species having joints 1 and 2 of antennae very 

 large, 3-8 slender, 9-11 much thickened; abdomen with seven seg- 

 ments, entirely covered by elytra: metasternum not reaching the 

 sides of the body. One of the two known species occurs in the 

 State. 

 934 (2914). NOSSIDIUM AMERICANUM Mots., Bull. Mosc., 41, 1868, 191. 



Oblong-oval, very convex. Head and thorax 

 piceous, strongly shining; elytra reddish-brown, 

 rather thickly clothed with long yellowish hairs; 

 legs and antenna? yellow. Thorax more than 

 twice as wide as long, hind angles rectangular; 

 sides rounded, distinctly margined, surface very 

 finely and sparsely punctured. Elytra not wider 

 than thorax, surface with rather deep, rugose 

 punctures in sinuate transverse rows ; tips broad, 

 much rounded. Length 1 mm. (Fig. 173.) 



Monroe County ; frequent, May 13-Jvme 

 9. Taken by sifting debris of beech stump. 

 Fig. 173. x 34. (Original.) Probably occurs throughout the State. 



