CHAPTER VII. 



ON THE FIVE FAMILIES OF PETALOCERA WHICH 

 LIVE ON PUTRID OR DECOMPOSED VEGETABLE 

 MATTER. 



JSlN"CE from the circumstance that has been mentioned of 

 their disposition in circles, it becomes very troublesome to 

 arrange thePetalocera in a cabinet according to their natural 

 affinities, the series prefixed to this chapter may be adopted 

 for the purpose ; and it is perfectly natural, provided the 

 connexion of the extreme families Geotrupidce and Rutelidcd 

 with the centre families Di/nastida and Anoplognathidtz, 

 be always borne in mind. The characters given to the ten 

 families in this table may, however, be thought too brief for 

 the inexperienced entomologist : and it is true indeed, that 

 they only express the forms of construction to one or other 

 of which every Petalocerous insect tends, and not those at 

 which they all actually arrive. Thus the Rutelidae and Geo- 

 trupida do not all possess a membranaceous process to their 

 maxilla? ; but the genera Chasmodia and Geotrupes, which 

 perhaps are the types of the families, possess such. I have 

 therefore imagined that it might be of some little service 

 to attempt the still more detailed definitions of each family 

 Avhich follow ; though to me it appears that any advantage 

 which may thus be gained, will be at the expense of some 

 natural affinity. And for this opinion I have no less autho- 

 rity than that of Linneeus, who could never be persuaded 

 to define his natural orders in botany, from a conviction 

 that the investigation of nature by means of preconceived 



