ELATERIDAE. 159 



presternum long, usually lobed in front, prolonged behind, 

 forming an acute process moving in the mesosternum. 



Mesosternum short, excavated in the middle for the recep- 

 tion of the prosternal process ; coxal cavities small, usually 

 angulated externally; side pieces large, epimera reaching the 



C0X93. 



Metasternum usually long, side pieces narrow, epimera 

 slightly visible. 



Elytra covering the abdomen (rarely abbreviated in the 

 female); epipleurae 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. 



Anterior coxae small, rounded, without trochantins, con- 

 tained entirely in the prosternum, in cavities open behind; 

 middle coxa? small, rounded or angulated externally, with a 

 distinct trochantin* in the second sub-family, but none in 

 the first ; posterior coxae 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 visible; tarsi 5-jointed, 

 simple or lobed beneath; claws simple, toothed, or pectinated; 

 onychium none, or very short and bisetose. 



A very large family, and including the Eucnemidse (regarded 

 by many as a distinct family), very sharply defined by the above 

 characters. A few of the species of the first sub-family, and the 

 majority of those of the third, possess the singular power of 

 springing in the air when placed on the back. This is effected 

 by extending the prothorax so as to bring the prosternal spine to 

 the anterior part of the mesosternal cavity, then suddenly relaxing 

 the muscles so that the spine descends violently into the cavity ; 

 the force given by this sudden movement causes the base of the 

 elytra to strike the supporting surface, and by their elasticity the 

 whole body is propelled upwards. 



It is consequently obvious that the existence of this leaping 

 power is dependent on a loose articulation between the pro- and 

 mesothorax; and, in fact, this is a remarkable character in the 

 majority of the genera of the family, though not apparent in most 



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

 all the genera examined of genuine Elateridse, but in no other except Pero- 

 thops, in which it is merely rudimentary. 



