270 COLEOPTERA OF NORTH AMERICA. 



Mexico and Arizona. I formerly considered these species as 

 constituting a section of Cysteodemus. 



Tribe II.— LYTTINI. 



Body generally winged ; elytra, in our genera, not shorter than 

 the abdomen, entirely closing together along the suture ; meta- 

 sternum long (except in Apterospasta) ; middle coxa? not over- 

 lapping the hind coxae ; side pieces of meso- and metathorax 

 plainly visible, not covered by the elytra ; claws generally cleft 

 to the base, the upper portion sometimes pectinate ; very rarely 

 they are armed with a tooth. 



Subtribes may be separated as follows : — 



Front not prolonged beyond the base of the antennse. Horiini. 

 Front prolonged ; frontal suture very distinct ; 



Mandibles prolonged, acute. Nemognathini. 



Mandibles obtuse, short. Lyttini. 



Sub-Tribe I.— Horiini. 



Head large, squarely truncate behind ; front without suture, 

 scarcely extending beyond the insertion of the antennae, which 

 are not very long, and not thickened towards the extremity ; the 

 eyes are transverse, and subreniform ; the mandibles extend be- 

 yond the labrum, and in some males of foreign species are quite 

 large ; the lobes of the maxillae are not elongated, and the palpi 

 are not dilated ; the claws of the tarsi are cleft to the base, the 

 upper portion is finely pectinate, the lower one is very slender ; 

 the tarsi are clothed with stiff hairs or bristles beneath. 



Three species are known in our fauna: one without wings, 

 Horia sanguinipennis Say, from the Northern and Middle States, 

 and two winged species from the vicinity of the Rocky Moun- 

 tains. They all belong to the genus Tricrania Lee, which is 

 distinguished from the foreign genera by the last joint of the 

 maxillary palpi being longer than the 3d, and by the triangular 

 head. 



Sub-Tribe II.— Nemognathini. 



Head triangular, squarely truncate behind (except in Gnathium) ; 

 front with distinct transverse suture, prolonged beyond the inser- 

 tion of the antennae, which are filiform or very slightly thickened 

 externally ; the eyes are transverse, rarely (Gnathium) oval and 

 oblique ; the mandibles are acute at tip and extend beyond the 

 labrum ; the outer lobe of the maxillae is generally prolonged into 



