358 COLEOPTERA OF NORTH AMERICA. 



The genera known to inhabit our fauna may be separated in 

 the following manner: — 



Posterior tibiae with articulated spurs ; posterior coxje wide, narrowing tlie 



first ventral segment. Spermophagus. 



Posterior tibiaB without articulated spurs ; posterior coxaj not uuirowiug 



the first ventral segment ; 



Anterior coxae separated by the prosternum. Caryoborus. 



Anterior coxae prominent, contiguous. Bruchus. 



The last two genera are not considered distinct by Lacordaire 

 and others. Spermophagus with one species occurs in the Atlantic 

 region, the other genera are found on both sides of the continent. 

 Many species of Bruchus have been widely distributed by com- 

 merce. 



Fam. LYIII.— tenebrionidae. 



Mentum variable in form, sometimes entirely closing the 

 opening of the mouth inferiorly ; ligula usually visible, some- 

 times concealed; paraglossse distinct ; labial palpi 8-jointed. 



Maxillas with two lobes, the inner one smaller, sometimes 

 armed with a terminal corneous hook; palpi -i-jointed. 



Mandibles usually short, robust, and furnished with a 

 basal tooth; emarginate at tip in the first and second sub- 

 families; either emarginate or entire in the third. 



Eyes usually transverse, Avith the anterior outline emar- 

 ginate. 



Antennas generally inserted under the sides of the head, 

 or at least under a small frontal ridge; usually thickened 

 externally; sometimes subserrate ; usually 11-jointed, very 

 rarely 10-jointed. 



Prothorax with epimera and episterna not separate; coxal 

 cavities separated by the prosternum (except in Dacoderus), 

 and entirely closed behind. 



Mesosternum short, side pieces usually attaining the coxie, 

 though in several tribes they are cut off by the sterna; in 

 the latter case no trochantin is visible. 



Metasternutn variable in length, side pieces sometimes 

 wide, sometimes narrow. 



Elytra rounded at tip, covering the abdomen, frequently 

 embracing its sides very far. 



Abdomen with five ventral segments, of which the first 

 three appear more closely connected than the others, though 

 not decidedly connate. 



