178 COLEOPTERA OF NORTH AMERICA. 



The species are rare, and are found under bark, or on leaves 

 of plants. Two tribes are indicated: — 



Antenn?e moderately distant ; maxillary palpi with the last joint acute; 



prosternal sutures and margin parallel. Melasini. 



Antennae approximate ; maxillary palpi with the last joint large, dilated ; 



prosternal sutures and margin convergent. Eucnemini. 



Tribe I.— MECASIIVI. 



Two genera, of slender form, both represented in our fauna, 

 alone constitute this tribe. They differ in several respects from 

 all other members of the faniil}^ and particularly by the large 

 size of the head, so that the eyes are entirely disengaged from 

 the thorax; the mouth is not pei'fectly applied to the prostcrnum, 

 as in the next tribe; the prosternum is truncate in front, and its 

 sutures are parallel, not running to the anterior angles of the 

 thorax, as in the other genera of this sub-family; the middle 

 coxaj are small, not angulated externally, and without trochautin; 

 the epimera are very transverse. 



Tibias broad, compressed. Melasis. 



Tibiai slender. Tharops. 



Tribe II.— EUClVEMirVI. 



Several genera, usually cuneiform, sometimes subcylindrical, 

 and easily recognized by the situation of the autennge in approxi- 

 mate grooves, which narrow the clypeus. The middle coxse are 

 small, rounded, not angulated externally, and without trochautin; 

 the epimera of the mesothorax are very transverse. Deltometopus 

 possesses a feeble leaping power, which has not been observed in 

 our other genera, although several of them probably may exhibit 

 the same movement. The antenniC are frecpiently received in 

 grooves, which run sometimes along the under side of the pro- 

 thorax, sometimes along the prosternal suture; the latter position 

 is assumed among our genera in Microrhagus, and in that the 

 grooves are quite shallow. The claws have a broad tooth in 

 certain species of Fornax. 



The following table, an abbreviation of that given in the 

 Monograph of de iJonvouloir, expresses the relation of our 

 genera: — 



