of Buprestidse and Elateridse. 193 



Then let us take some species or other (it does not matter 

 which) of the divisions of Throscidse, Melasidse, Eucnemidae, 

 Elateridse, or Cebrionidse, and let us lift the prosternal spine out 

 of its bed on the mesothorax, and we shall find that the bed is 

 not by any means constructed only with regard to that spine ; 

 so that the arrangement is entirely different from that of the 

 Buprestidse. The place in which the prosternal spine rests 

 always terminates behind in a deep excavation, which would 

 be as superfluous for the accommodation of that spine as it is 

 necessary for the accommodation of the " springing-spine " 

 (mucro saltatorius), the essential instrument of the springing 

 beetle, which has hitherto been either overlooked or misunder- 

 stood, having been confounded with the prosternal spine. The 

 fact is, that when the articulation of the prothorax with the 

 mesothorax is not very free (that is, in most cases), the spring- 

 ing-spine is, on account of the limited space, placed on the 

 upper surface of the prosternal spine, forming an angle with it, 

 and therefore hidden by this when the animal is viewed from 

 below. It is only when drawn out by the animal for use in 

 springing, or when tlie prothorax is entirely loosened, that it is 

 seen. By degrees, as the articulation of the prothorax with 

 the mesothorax is freer, and the mesothorax more salient, 

 the springing-spine assumes a more horizontal direction, and 

 appears behind the posterior extremity of the prosternal spine ; 

 the boundary between the two is in this case marked by a small 

 tooth, which is nothing but the extremity of the prosternal 

 spine. Finally, in those Elaters where the joint in question is 

 entirely free and open below, this little tooth also disappears, 

 and with it the last indication of the original position of the 

 springing-spine, which in this last case appears simply as the 

 continuation of the prosternal spine. 



We shall do well to pause a few moments after having gained 

 these results. We have seen that the larvse of Sternoxi group 

 themselves round two distinct types, and we now see this bifur- 

 cation confirmed in the perfect animals by equally decisive and 

 thorough-going marks of distinction. We found the type of the 

 BuprestidjE to be that of an animal organized for flight, that of the 

 Elateridse to be characterized by the springing-mechanism. But 

 the latter type is less one-sided than the former. The Buprestis- 

 larva and its congeners are always xylophagous, burrowing in 

 timber, and there is consequently not much room for variety in 

 shape; whether the egg is deposited in clefts of the bark of trees, 

 in the tenderer stem of herbs and shrubs, or in the parenchyma of 

 leaves, the demands which the propagation of the species makes 

 upon the structure of the beetle remain upon the whole the 

 same; but time and strength will at the same time be to such a 



Ann. ^ Mag, N. Hist. Ser. 3. Vol. xviii. 14 



