2 COLEOPTERA OF NORTH AMERICA. 



The antennae are inserted upon the front, above the mandibles; 

 they are always 11-jointed, with the four inferior joints glabrous 

 and polished, the others pubescent ; they are usually filiform, rarely 

 thickened externally. 



The thorax is usually cordate, sometimes cylindrical, rarely qua- 

 drate; the dorsal surface is marked by an anterior and posterior 

 transverse impression, and a dorsal line connecting the two trans- 

 verse impressions ; the lateral margin is not well denned, as in 

 most of the genera of the next family; the prosternum is narrow, 

 not produced behind; the episterna and epimera are distinctly 

 defined by sutures, and the anterior coxae are globular, with the 

 cotyloid cavities entire. 



The mesosternum is obliquely declivous, deeply emarginate 

 behind; the epimera and episterna are sometimes connate, without 

 suture, and sometimes distinct; in the latter case the suture runs 

 diagonally, and the epimera extend to the middle coxae, which are 

 globular. 



The metasternum is pointed in front and behind, reaching the 

 middle of the second ventral segment; the epimera are large in 

 the winged species, small in the apterous ones; the episterna are 

 small, and frequently indistinct. The posterior coxae are triangular, 

 dilated and prominent internally, concave behind for the motion 

 of the thighs; they do not extend to the margin of the body, but 

 are inclosed by the side pieces of the metathorax, and the first 

 ventral segment. 



The elytra cover the body, and are rounded at the tip; some- 

 times they are connate, and sometimes (as in Amblychila) embrace 

 widely the flanks of the abdomeu ; the wings are usually well 

 developed, sometimes wanting. 



The legs are slender, usually long; the tibiae have two distinct 

 terminal spurs; the tarsi in our genera are filiform, the first three 

 joints of the anterior ones of the male usually dilated, and densely 

 clothed with hair beneath. The claws are acute, and simple. 



The abdomen is composed in the female of six ventral segments ; 

 in the male the sixth segment is usually deeply emarginate, and a 

 small seventh segment is thus seen, but in Amblychila the abdomen 

 is alike in both sexes; the three anterior segments are closely con- 

 nate, the first is visible only on the sides, the second is acute in the 

 middle, and reaches the point of the metasternum; the others are 

 movable. The dorsal segments, as first observed by Dr. Schaum, 



