48 GEOGRAPHY OF THE PETALOCERA. 



expected to avoid an English cold summer rather than 

 a Swedish cold winter. 



In other cases the distribution of the Petalocera ap- 

 pears to have been regulated by a higher purpose. Thus, 

 if my observations on the subject have not deceived me, 

 the species of coprophagous insects from within the tro- 

 pics are to those from without, nearly in the proportion of 

 4:3; which, if we reflect on the services rendered in hot 

 climates by these scavengers of nature, appears to be a 

 limitation that is in some measure required by necessity. 

 A similar purpose of utility may account for the species 

 of coprophagous insects, that is, those composing the 

 three families Geotrupida, Scarabaidoz, and Aphodiidaz, 

 being to the number of species which compose the re- 

 mainder of the Saprophagous Petalocera in the propor- 

 tion of about 3:2. — Ignorant as we are of the habits of 

 the Rutelida and Anoplognathida, it is impossible at 

 present to carry the same kind of investigation among the 

 thalerophagous insects ; though it may excite some little 

 curiosity to know what proportion the species of phyllo- 

 phagous Petalocera bear to those which feed on flowers. 

 If it be allowable to argue from the general oeconomy of 

 nature, it would seem that the number of the former 

 ought to be predominant, and this I suspect to be really 

 the case. 



But this highly amusing subject must be left to some 

 future period, when the continued prosecution of disco- 

 veries by intelligent travellers shall have supplied ento- 

 mologists with that information from which alone such 

 calculations must always be derived. 



