18 COLEOPTERA OF NORTH AMERICA. 



suits' nests, while the wonderful g^cnns Leptoderus, not yet found 

 in America, lives in caves; it differs remarkably from other 

 genera of the family Ijy the long cylindrical thorax, and the 

 globose, connate elytra. Like nearly all cave insects, it is desti- 

 tute of eyes. 



According to the structure of the coxae and the form of their 

 cavities the following tribes are defined :• — 



Posterior coxte simple. 



Anterior coxse more or less transverse at base and with trochantin. 

 Anterior coxal cavities open beliind. 



Posterior coxae contiguous. Silphini. 



Posterior coxae separated. 



Anterior coxae prominent ; five ventral segments. Lyrosomim. 



Anterior coxae not prominent ; six ventral segments. Pinodytini. 



Anterior coxal cavities closed beliind. Anisotomini. 



Anterior coxae cylindric-conic, without trochantin, the cavities closed 



behind, often widely. Cholevini. 



Posterior coxae laminate. 



Anteiior coxae witli trochantin, the cavities closed behind. Clamijini. 



Tribe I.— SILPHIIVI. 



Body never globose, sometimes elongate, usually oval, or even 

 nearly circular, and then usually with a thin margin of the thorax 

 and elytra extending beyond the body; the antenna are 11 -jointed, 

 but with the second joint in one genus (Necrophorus) almost 

 obsolete; with a globose 4-jointed club in that genus, gi'adualh- 

 clubbed in the others. Anterior coxa; conical, pronvinent, con- 

 tiguous, with large trochantin, the cavities strongly angulate ex- 

 ternally and open behind, very widely in Necrophorus and Silpha, 

 and partially closed in the other genera. Middle coxje widely 

 separated in these two genera, narrowly separated or even con- 

 tiguous in the others. Posterior coxae contiguous. Abdomen 

 with six segments, except in Sphf^rites. Tarsi 5-jo'nted. 



This tribe contains the largest insects of the family; the spe- 

 cies of Necrophorus are remarkable for the black elytra, truncate 

 at tip, and ornamented with large red spots They live on dead 

 animals, and a pair of them will, bury the body of a small mammal 

 with wonderful rapidity. Silpha is also easily recognized by the 

 rounded outline and thin margin. 



The following table gives in brief the important characters 

 separating the genera:— 



