FAMILY III. rriKT 



margin of the under surface; pygidium of male transversely di- 

 vided ; tarsal joints set with small bristles beneath. 



In addition to the characters mentioned, the Thecesterninae 

 have the mandibles short, stout, pincer-shaped and without an 

 apical scar; antennae short, inserted in front of the eyes, fimicle 

 7-jointed, its last joint wider and forming part of the club, which 

 is oval and pointed ; head strongly def lexed ; eyes transverse and 

 in repose partly hidden by the short ocular lobes of thorax ; beak 

 short, stout, strongly constricted at insertion of antennae; thorax 

 rounded in front and projecting partially over the head, deeply 

 excavated beneath for the reception of the head and beak ; elytra 

 connate, rigid, covering the pygidium ; abdomen with first and 

 second ventral segments long, closely united at middle, third and 

 fourth short, the two together only as long as fifth ; front coxae 

 small, contiguous, rounded, middle ones separated, hind ones 

 more widely separated and distant from the sides of the elytra; 

 legs slender, tibiae truncate at tips and armed with two small 

 spurs; tarsi 4-jointed, narrow, third joint in our species not di- 

 lated or bilobed ; claws simple, slender, free. 



The Byrsopidie of Lacordaire, according to Sharp (Biol. Cent. 

 Am. Col., IV, ]. '>, ]>. 80). must be wholly dissolved, as being 

 composed of forms having little relation one with another. More- 

 over. Tltcrcsteniiix 1831, has three years' precedence over Byrsops 

 1834. Sharp states that the true position of Tlicccsternus is un- 

 known, but may be with the Cryptorhynchini which have the same 

 excavated breast. LeConte (1876, 12) placed it as a tribe "dis- 

 tinguished from other Byrsopidae by the peculiar conformation 

 of the prosternum which forms a triangular plate in front of the 

 coxa\" In our own view, while the feebly elbowed antennae with 

 comparatively non-compact club indicate primitive character, the 

 excavated breast, roughly sculptured surface, narrow tarsi with 

 third joint not dilated, and general facies, make a position be- 

 tween Cryptorhynchini and Cossonina* most appropriate and 

 most easily found by the student. The subfamily is represented 

 in North America by the single genus: 



I. THECESTKRXUS Say, 1831. (fir., "box" + "breast.") 



This genus, so named on account of the deep excavation in 

 the prosternum for the reception of the beak, is distinguished by 

 the presence of a triangular plate in front of the fore coxae, this 



