ELATEIUDAE. 177 



A very large family, and including the Eucneminte and Cebriu- 

 nina; (reganled by many as distinct faniilies), very sharply dolined 

 by the above characters. A few of the species of the lirst sub- 

 I'aniily, and a majority of those of the second, 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 prosternai 

 spine to the anterior part of the mesosternal cavity, then sud- 

 denly 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 

 genera of the first sub-family. 



All the species are vegetable feeders; and the larva) live, some 

 in the earth, others in rotten wood, others prey upon living plants. 



Five sub-families may be defined, as follows: — 



Posterior coxre laminate ; troclianters small. 



Labnim concealed; antennre somewhat distant from the eyes, tlujir 



insertion narrowing the front. EucNEMiN^Ti. 



Labriira visible, free; antenn.-e arising near the eyes under the frontal 



margin. Elaterina:. 



Labrum transverse, connate with the front. 



Ventral segments six ; ungues simple : tibial spurs well developed. 



Ceckionin/t-:. 

 Ventral segments five ; ungues serrate ; tibial spurs moderate. 



Perotuopin^e. 



Posterior coxre not laminate ; trochanters of middle and posterior legs 



very long. 



Labrum short, transverse, connate with the clypeus ; front gibbous : 



ungues serrate. Ckrophytin/I':. 



Sul)-Family I.— EUCNEMIN/E. 



The only characters separating this from the genuine Elaterina> 

 arc found in the insertion of the antenna) upon the front, at the 

 inner extremity of transverse grooves, before which the front is 

 expanded again, and the labrum indistinct; the prosternum is 

 nearly truncate in front, and the head is always defiexed, and 

 applied to the sternum in rcipose. 

 12 



