212 



COLEOPTERA OF NORTH AMERICA. 



derived from the 3d and 4th ventral segments, this family may, in 

 my opinion, be properly divided into three sub-families :* — 



Ventral segments entirely corneous ; 



Middle coxa? without trochantin. Tentyriim. 



Middle coxae with distinct trochantin. AsmiDiE. 



Ventral segments 3 and 4 with the hind margin coriaceous. 



TENEBKIONIDiE. 



Sub-Family I.— TENTYRIIDAE. 



The species of this sub-family are distinguished by the middle 

 coxa? being entirely inclosed by the sterna, without any trochantin ; 

 the side pieces of the mesothorax consequently do not extend to 

 the coxal cavities ; the ventral segments are entirely corneous, the 

 3d and 4th having no vestige of a posterior coriaceous margin. 

 Besides these two distinguishing characters, common to all the 

 tribes, there are others worthy of notice, which belong to indi- 

 vidual tribes, and are not found to recur in the other two sub- 

 families. 



The species, with the exception of Epitragini and a few Thino- 

 batini, are apterous, and the metasternum is very short, except in 

 the winged species. In Zopherini the eyes are very finely granu- 

 lated, a singular exception in this family. The mentum is fre- 

 quently very large, so as to fill entirely the gular cavity, and to 

 cover completely the maxillae and ligula, so that the gular process 

 usually supporting it ceases to exist. This character recurs again 

 only in certain Asidini of the next sub-family. The tarsi are 

 sometimes spinous, sometimes pubescent beneath. The front is 

 frequently trilobed. 



The tribes repi'esented in our fauna are as follows : — 



Mentum concealing both maxillae and ligula ; 



Episterna of metathorax very wide ; front trilobed. I. Epiphysini. 



Episterna of metathorax narrow ; 



Pro- and mesosternum not articulating together ; 



Front lobed, body apterous. II. Gnathosiini. 



Front not lobed, body sometimes winged. III. Thinobatini. 



* Two described insects cannot be placed in the arrangement of this 

 family, from want of sufficient knowledge of their characters. The first, 

 Dijamathes Sahlbergii Mann. Bull. Mosc. 1853, ii. 265, is said to be similar 

 in form to Nycteli'a, but to have antennae like Gnathosia ; the form of men- 

 tum, if known, would determine its position. The second is Pedinus sutu- 

 ralis Say, Journ. Ac. Nat. Sc. Phil., hi. 263, which has not been identified 

 in recent times. 



