HISTORY OF ENTOMOLOGY. 481 



than I can afford ; I must therefore refer you to his 

 work for more particular and detailed information on 

 that subject. With regard to the analogy between op- 

 posite points of contiguous circles, you may get a very 

 good idea of it from his diagram of Saprophagous and 

 Thalerophagous Petalocerous beetles, which I here 

 subjoin. 



Cetoniadae 



Dynastidse j Anoplognathidse g 



s 

 Aphodiadae / \ ' Glaphyridse 



It is a very singular circumstance that in these two 

 circles we have two sets of insects, one impure in its 

 habits and feeding upon putrescent food, and the other 

 clean and nourished by food that has suffered no decay, 

 set in contrast with each other, and that in each of the op- 

 posite groups, the one has its counterpart in some respect 

 in the other. In none is this more striking than the Sca- 

 rdbceidce and Cetoniada, both remarkable for having soft 

 membranous mandibles unfit for mastication, and both 

 living upon juices, the one in a putrescent and the other 

 in an undecayed state a . 



a Other systems or methods have been promulgated by various 

 authors, as by Schaeffer, Scopoli, Geoffrey, &c. Walckenaer and 

 Blainville have proposed one founded on the number of the legs of 

 insects ; but those in the text are the principal and best known. 

 AT. Diet. ffHist. Wat. xvi. 277. 



VOL. IV. 2 I 



