TBNEBRIONIDAE. 211 



Abdomen with five ventral segments, of which the first 

 three appear more closely connected than the others, though 

 not decidedly connate. 



Leo-s variable; anterior coxa? globose, rarely oval, not 

 prominent, without trochantin ; middle coxas rounded, with 

 or -without trochantin; hind coxae transverse, more or less 

 separated ; tarsi without membranous lobes ; anterior and 

 middle ones 5-jointed ; hind tarsi 4-jointed, the first joint 

 almost always longer than the* second; claws simple. 



This family contains a large 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 into 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 I 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 any 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 

 <>r Xebraska Paver ; from that point they increase in number of 

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

 the characteristic feature of the insect 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 des Coleopteres, vol. 5, a work not less admirable 

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

 first successful effort towards a rational classification of this most 

 diilicult family. The recognition of the value of the form of the 

 middle coxae, and the vestiture of the tarsi in establishing natural 

 divisions and tribes, we owe to his acute observation. 



By combining with these characters another not before observed, 





