512 COLEOPTERA OF NORTH AMERICA. 



Our genera may ])e separated as follows: — 



Beak thick, neither dilated at tijj nor cylindrical, slightly narrowed from 



the base to the tip, convex. 2. 



Beak very short, ixarallel on the sides. 4. 



Beak longer, gula only feebly concave transversely. Phloeophagus. 



2. Club rounded, pubescent, feebly annulated. 3. 

 Club corneous, truncate at tip, which is spongy; funicle 5-jointcd. 



Wollastonia. 



3. Fuiiicle 5-jointed. Amaurorhinus. 

 Funicle 6-jointed. Hexarthrum. 

 Funicle 7-jointed. Elassoptes. 



4. Tarsi dilated, antennal grooves long. Rhyncolus. 

 Tarsi narrow, antennal grooves very short. Stenoscelis. 



Hexarthrum is found in Louses in New Yoi-k and in Wash- 

 ington, D. C, and is probably introduced. Elassoptes lives on the 

 sea-shore of California; Rhyncolus extends across the continent; 

 the other genera occur in the Atlantic re2:ion. 



Fam. LXXXIL— scolytidae. 



Mentnm moderate in size, varying in form in some genera 

 according to sex ; without gular peduncle (except in Ilylastes, 

 where it is very small); ligula and palpi small, the former 

 sometimes retracted, sometimes prominent. 



Maxilhe exposed, palpi stout and short. 



Mandibles stout, curved, more or less toothed on the 

 inner side. 



Antennas inserted on the sides of the head between i,ne 

 eyes and mandibles; composed mostly of scape and club, 

 funicle usually very short, from 1- to 7-jointed; club large, 

 solid, annulated, or rarely (Phloeotribus) lamellated; surface 

 of the club more or less sensitive according to genus. 



Head prominent in some tribes, deflexed q,nd protected 

 by the prothorax in others; eyes usually large and trans- 

 verse; beak never long, frequently so short as to be not 

 apparent. Labrura feebly developed, sometimes visible. 



Prothorax truncate in front, exposing the head (Platy- 

 podince, Scolytini, and Plylurgini), or prominent, convex, 

 and rounded (most Tomicini); lateral edge not distinct (ex- 

 cept in Scolytus), and prosternal sutures obliterated; flanks 

 excavated for the partial reception of the front legs in 

 Platy^podinjB ; coxal cavities usually confluent; separated 

 in a few genera. 



