210 COLEOPTERA OF NORTH AMERICA. 



or linear, spurs not distinct ; tarsi 4-jointed, joints 1 — 3 very- 

 short, equal, 4th long, with simple claws. 



Yery small insects, found under bark of trees, and in the dry 

 and woody species of fungus, such as Polyporus. They are 

 usually gregarious. In some of the species the head and the 

 anterior margin of the thorax are in the male ornamented with 

 horns. 



Our genera are hut three in number, all having the tarsi free, 

 not received in tibial grooves. 



Antennae 10-jointed, tibiae not serrate. Cis. 



Antennae 9-jointed. Ennearthron. 



Antennae 8-jointed, tibiae not serrate. Ceracis. 



The last genus is not yet represented in the Pacific fauna. The 

 other two are distributed on both sides of the continent. 



Fam. xlvil— tenebrionidae. 



Mentum variable in form, sometimes entirely closing the 

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

 times concealed ; paraglossas distinct ; labial palpi 3-jointed. 



Maxillas with two lobes, the inner one smaller, sometimes 

 armed with a terminal corneous hook ; palpi 4-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, with the anterior outline emar- 

 ginate. 



Antennae generally inserted under the sides of the head, 

 or at least under a small frontal ridge ; usually thickened 

 externally ; sometimes subserrate, very rarely (male of Ehi- 

 pidandrus) pectinate; 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 coxae, 

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

 the latter case no trochantin is visible. 



Metasternum variable in length, side pieces sometimes 

 wide, sometimes narrow. 



Elytra rounded at tip, covering the abdomen, frequently 

 embracing its sides very far. 



