110 COLEOPTERA OF NORTH AMERICA. 



Prothorax with the side pieces not separate ; coxal cavi- 

 ties large, transverse, open behind, separated by the pro- 

 sternum, which is short, truncate in front, slightly prolonged 

 behind, fitting into the mesosternum. 



Mesosternura small, prominent, emarginate, or excavated; 

 side pieces largely attaining the coxae. 



Metasternum short, broad ; side pieces narrow ; epimera 

 not visiblejr 



Elytra covering the abdomen; epipleurae obsolete behind. 



Abdomen with five ventral segments, the anterior three 

 subconnate in some genera. 



Anterior coxae transverse, not prominent, with large tro- 

 chantin ; middle coxae flat, transverse, oval, with large tro- 

 chantin; posterior coxae subcontiguous, extending to the 

 margin of the body, transverse, dilated, into a plate partly 

 protecting the hind thighs. 



Legs short, stout, retractile ; tibiae dilated, usually sulcate 

 externally for the reception of the tarsi ; tibial spurs distinct; 

 tarsi short, 5-jointed, the third joint frequently prolonged 

 into a membranous lobe beneath, last joint nearly as long as 

 the others united ; claws simple. 



This family comprises three sub-families, as follows : — 



Antennse inserted at the side of the head ; 



Head prominent, mentum large. Nosodendridje. 



Head retracted, mentum small. Byrrhid;e. 



Antenna inserted on the front ; head retracted. Chelonariid^;. 



Sub-Family I.— NOSODENDRIDAE. 



But a single genus, Nosodendron, constitutes this sub-family. 

 It is represented in Europe by one species, and in the Atlantic 

 States by another, N. unicolor Say. It is sufficiently distin- 

 guished by the large, elongate, semi-elliptical mentum, entirely 

 closing the mouth below, leaving only a very narrow portion of 

 the maxillae to fill the fissure on each side ; the head is advanced ; 

 the antennae 11-jointed, situated under the side of the head; the 

 labrum is indistinct; the tarsi not lobed. 



The insect is less than one-fourth of an inch long, oval, convex, 

 black, densely punctured, and is found under bark of trees. 



