GENERA OF DYNASTIN^E. 233 



nion can be established upon two distinct grounds : first, 

 on the nature of their food, as indicated both by facts of 

 economy and of structure ; and, secondly, by their or- 

 gans of locomotion. In the latter, indeed, no less 

 than in the former, there are numerous modifications ; 

 and these will, doubtless, indicate some of the most 

 natural of the minor groups, or sub -genera; but we 

 have yet seen no insects which did not come under one 

 or other of these groups, or which did not fall into the 

 natural series by which they are connected to others. 

 We have had frequent occasion, in our progress through 

 the vertebrate animals, to show how much the peculi- 

 arity of colour enters into the composition of natural 

 groups. The same remarks are applicable, as every 

 experienced entomologist is aware, to insects. In the 

 present case, it may be observed, that the whole of the 

 genuine Dynastince are either deep glossy black, or dark 

 brown ; and although very many of the Megasomince, 

 as D. Actaon, &c., are of the same dark colours, yet the 

 majority have the elytra of a livid green, as if they 

 had been coloured with the weakened sap of the decay- 

 ing trees upon which the insects themselves chiefly fed. 

 This, of course, is mere conjecture, yet it is by no 

 means either impossible or improbable. 



(206.) The genera we consider the most typical of 

 our Dynastince, are Oryctes, Phileurus, Hoplites (Ene- 

 ma Kirby), and Archon. This, consequently, is also a 

 limited group ; which, however, is not yet thoroughly 

 analysed as respects our views concerning it. All that 

 we know of the habits of the insects contained in 

 it, we have already stated. The forms are more 

 elongate than any of the preceding, and also some- 

 times considerably depressed, as in Phileurus, Enema, 

 and Heteronychus. We do not expect that any of them, 

 in their perfect state, are sessorial, although they have 

 all the requisite structure. They are considerably dis- 

 persed over the world; although Phileurus and Enema 

 are exclusively American ; Cryptodon, African, as well as 

 Heteronychus. 



