176 COLEOPTEEA OF NORTH AMERICA. 



Fam. XLI.— elateridae. 



Mentum small, corneous, quadrate, sometimes rounded in 

 front; ligula without paraglossae; labial palpi 3-jointed. 



MaxilltB exposed at the base, with two lobes, the outer one 

 sometimes very small; palpi short, 4-jointed. 



Antennge inserted on the front in grooves, or under the 

 margin of the front, 11-jointed, rarely 12-jointed, more or less 

 serrate, sometimes flabellate or pectinate, the outer joints 

 rarely in the first sub- family enlarged, forming a serrate club. 



Head frequently retracted, sometimes advanced; usually 

 applied to the prosternum beneath; mandibles usually small, 

 sometimes slender and prominent, corneous; labrum distinct 

 in most species, indistinct in the first sub-family. 



Prothorax with the side pieces not separate; coxal cavi- 

 ties small, rounded, not closed behind by the mesosternum; 

 prosternum long, usually lobed in front, prolonged behind, 

 forming an acute process moving in the mesosternum. 



Mesosternum short, excavated in the middle for the re- 

 ception of the prosternal process; coxal cavities small, usu- 

 ally angulated externally; side pieces large, epimera reach- 

 ing the coxne. 



Metasternum usually long, side pieces narrow, epimera 

 slightly visible. 



Elytra covering the abdomen (rarely abbreviated in the 

 female); epipleurte distinct, extending to the apex; scutel- 

 lum visible. 



Abdomen with five free ventral segments, fifth rounded at 

 the apex (except in the female of Euthysanius), sixth visible 

 in some of the tribe Plastocerini and in Ccbrionina?. 



Anterior coxas small, rounded, without trochantins, con- 

 tained entirely in the prosternum, in cavities open behind; 

 middle coxre small, rounded or angulated externally, with a 

 distinct trochantin,* except in the first and fifth sub-fami- 

 lies ; posterior coxte transverse, oblique, contiguous, dilated 

 into a plate covering in part or entirely the thighs (except 

 in Cerophytum). 



Legs short, sometimes contractile; tibia; usually slender, 

 with the spurs very small, or scarcely visibli\ moderately 

 long in Cebrioninie; tarsi 5-jointed, simple or lobed be- 

 neath; claws simple, toothed, or pectinated; onychium 

 none, or very short and bisetose. 



* Lacordaire states that no trochantin is visible ; but it is distinct in 

 all the genera examined of genuine Elateridae, and in no otlier except 

 Perotliops, in which it irf merely rudimentary. 



