COI-EOPTERA. — NfACROSTERNI. 225 



is of a firm consistence, the presternum or pectus of the prothorax 

 advanced in front beneath the mouth, and generally with an impres- 

 sion on each side beneath for the reception of the antennae (which 

 are always short), and likewise posterioi'ly produced into a point, 

 which is received into an excavation in front of the mesosternum, or 

 pectus of the mesosternum ; the legs are partially or entirely retrac- 

 tile ; the head inserted vertically, as far as the eyes in the frontal 

 cavity of the prothorax ; the body is generally of an elliptic elongate 

 form, sometimes conic or trigonate, and narrowed behind ; the legs 

 are short, and the posterior angles of the thorax more or less acutely 

 produced. 



In their perfect state, these insects feed either upon wood, leaves, 

 flowers, or sap ; the larvae are several years in arriving at their full 

 growth. 



The two Linnaean genera above-mentioned form the types of the 

 two families Buprestidae and Elateridae, the transition between which 

 is very gradual, so that the point of separation is obscure. M. 

 Lacordaire, in his Memoir upon the habits of the Coleoptera of South 

 America (Atm. des Sc. Nat. June, 1830), has observed that various 

 genera, such as Pterotarsus, Galba, Eucnemis, Lissomus, and Crypto- 

 stoma, ranged by Latreille amongst the Elateridae, have not the power 

 of leaping, which so eminently distinguishes this family, the convexity 

 of their bodies preventing them from obtaining a " point d'ajipui " 

 upon the surfaces upon which they are laid upon their backs, and are 

 consequently able only to roll over ; and therefore suggesting that, 

 from their habits, they should form a distinct family, nearly allied to 

 the Ptinidae and Lymexylonidae. Without, however, denying this 

 affinity, Latreille has endeavoured to remove the difficulty by the 

 establishment of two new tribes or families, namely, the Eucnemides, 

 more nearly allied to the Buprestidae, and the Cerophytides to the 

 Elateridae. As these two groups are, however, of very small extent, 

 and as they possess many characters in common, I shall provisionally 

 consider them as forming one group (Eucnemidae) of minor value, 

 divisible into two sections, intermediate between the Buprestidae and 

 Elateridae. 



