150 COLEOPTERA OF NORTH AMERICA. 



Maxillae exposed at the base, with ciliate, unarmed lobes ; 

 palpi short, 4-jointed. 



Antennae inserted upon the front, 11-jointed, serrate, the 

 outer joints usually furnished with pores, which are diffused 

 on the sides, or concentrated in a fovea on the inferior margin 

 or at its extremity. 



Head immersed in the thorax to the eyes, which are ellip- 

 tical, and never emarginate; labruni small, prominent; man- 

 dibles short, stout. 



Prothorax with the side pieces not separate from the upper 

 piece; coxal cavities separated by the prosternum, widely 

 open behind; prosternum prolonged behind, fitting into the 

 mesosternum, or even the metasternum. 



Mesosternum short, excavated, so that the visible part is 

 frequently divided into two portions, which complete the 

 anterior coxal cavities; side pieces large, diagonally divided; 

 epimera narrowly attaining the coxae. 



Metasternum with the side pieces narrow; epimera visible. 



Elytra covering the abdomen, or leaving only the pygi- 

 dium exposed ; epipleurae narrow ; wings large. 



Abdomen with five ventral segments, the first and second 

 connate, the others free; the fifth joint frequently emarginate 

 in the males, leaving a small sixth joint visible. 



Anterior coxae separate, small, globular, received between 

 the pro- and mesosternum, with the trochantin distinct; 

 middle coxae separate, globular, with the trochantin distinct; 

 posterior coxae transverse, usually nearly contiguous, con- 

 cave behind, dilated into a plate partially covering the 

 femora when retracted. 



Legs short; tibiae usually slender, with two small terminal 

 spurs; tarsi 5 jointed, the first four joints with more or less 

 developed membranous appendages beneath; onychium none. 



The species of this family are, in general, elongate in form, and 

 ornamented with metallic colors ; the larvae perforate the stems of 

 living plants, and the perfect insects are found partly on flowers, 

 partly sunning themselves on trees, during the hotter seasons of 

 the year. 



A monograph of the species belonging to our fauna has been 

 published by me in the Transactions of the American Philosophi- 

 cal Society, vol. XI, in which, with slight modifications, I adopted 

 the classification of Lacordaire ; the characters of the groups have 

 been farther modified by the views of Duval, and the divisions 

 here proposed are based upon renewed observations, though the 



