INTRODUCTORY REMARKS. IX 



individuals of these species. Thus, there is a certain parallelism of 

 contrast between this latter genus and the portion of the group now 

 under consideration ; for while, on the one hand, we have an actual 

 . paucity of examples (combined with comparative paucity of species) 

 and a limited geographical range to each species, — on the other hand, 

 we have abundance of examples (combined with abundance of so- 

 called species) which occupy a very extended geographical range ; 

 that is, that there is in the latter case an all-pervading and power- 

 ful influence in favour of increase, which in the former seems to be 

 wholly or almost entirely wanting. What may be the conditions and 

 what the limits of this influence, why it affects the one and not the 

 other group, we cannot now discuss ; doubtless the question is as 

 interesting as it is clifiicult : it is interesting because it is the investi- 

 gation of a principle affecting all life ; and it is difficult because our 

 present means of knowledge are so scanty, and because it is so easy 

 to fruitlessly dogmatize, and so hard to examine and in patience 

 wait. 



No travellers or collectors have given us any detailed information 

 respecting the habits of these insects, either in their earlier stages or 

 in their mature existence ; it is probable that they pass the larva and 

 pupa stages under conditions closely similar to those of the same 

 group in Europe. Perty says of them (Delectus Anim. Artie. 1830, 

 p. xvii), " quoad mores, parum inter se differunt, pleraque plantas 



frequentant (p. xviii) Halticoz in Brasilia copiosissime totum per 



annum cequali numero adsunt ; magnitudine Europasas valde superant, 

 moribus conveniunt. Pleraque in agmina congregantur, et copidationes 

 hybridce sapissime observantur." 



Lacordaire, in his valuable work on Subpentamerous Coleoptera 

 (vol. i. p. xl), describes the general form of the larvae of this group as, 

 " iii. Larues mineuses. Larves allongees, subcylindriques, attenuees a 

 leurs deux extremites, non mamelonees. Nymphes subissant leur me- 

 tamorphose dans Vinterieur des feuilles ok a vecu la larve, ou dans la 

 terre. — Altica." 



In their perfect state, the insects of the group (as represented by 

 the genus (Edionycliis) are most abundant throughout the whole of 

 Brazil. The traveller sees them flying across his path, or sunning 

 themselves upon some leaf or flower ; they may be taken readily by 



