TENEBRIONIDAE. 359 



Legs variable ; anterior ooxse globose, rarely oval, not 

 prominent, without trochantin; middle coxae rounded, witli 

 or witliout trochantin; hind coxae transverse, more or less 

 separated; larsi without membranous lobes; anterior and 

 middle ones y-joiiited ; hind tarsi -i-jointcd, the first joint 

 ahiiost always longer than the second; claws simple. 



This family contains a lai'ge number of genera, possessing in 

 common very few characters, yet linked together by such gradual 

 changes in structure that their classification presents almost in- 

 superable difficulties. The division iuto tribes can scarcely be 

 exhibited in a tabular form, on account of the varied relations 

 exhibited by the members of some of the tribes. 



The species live upon vegetable matter in various conditions; 

 the habits of those contained in the respective tribes will be 

 mentioned below. 



The limits of the family are very well defined, although by 

 Lacordaire certain genera have been retained, which we have 

 found it necessary to exclude; these are Boros, Cononotus, and 

 Penthe, in all of which the anterior coxal cavities are open behind. 



The distribution of the genera of this family is very remarkable. 

 Of those without wings scarcely tuiy are common to the two con- 

 tinents. With the exception of three, they are not represented in 

 North America, east of the longitude of the mouth of the Platte 

 or Nebraska River; from that point they increase in number of 

 genera, species, and individuals, until, in California, they form 

 the characteristic feature of tiic Coleopterous fauna. 



The representation of genera on this continent being thus im- 

 perfect, the characters given in the short synoptic tables will not 

 always enable our genera to be distinguished from those of other 

 countries. The student, for such purpose, must consult Lacor- 

 daire's Genera dcs Colcopteres, vol. 5, a work not less admirable 

 for the wonderful industry displayed in it, than for being the 

 first suceessful effort towards a rational classification of this most 

 difficult fanuly. 



This family may be projjcrly divided into three sub-families:* — 

 Ventral segments entirely corneous ; 



Middle coxae without trochantin. Tkntyriin-u. 



Middle coxse Avith distinct trochantin. Asidin-t^;. 



Ventral segments 3 and 4 with the hind ma'-gin coriaceous. Tknebkioxix/v:. 



* One described species, Pcffimm mtnrnHK Say, Journ. Acad. Nat. Sci. 

 Phila., iii. 2G3, has not been identified in recent times. 



