OlSr DECOMPOSED VEGETABLE MATTER. 59 



they comprise the least of the Petalocera ; and though re- 

 sembhng each other excessively in general structure, differ 

 extremely in the manner of living, some being coprophagous, 

 and others living on putrescent vegetable matter generally 

 marine. These last insects consequently lead to that family 

 of Petalocera which frequents sandy situations. 



Of all the Saprophagous Petalocera the Ap]iodiid<K are 

 the most common in England, and seem to replace with 

 us the want of the Scarabaida. They appear indeed to 

 be equally frequent over the whole of the north temperate 

 zone, and I have made out the proportion of tropical insects 

 of this family to be to those from countries without the 

 tropics as 1 : 8. None have hitherto been brought from 

 New Holland, though we are acquainted with Aphodiid(B 

 from the Cape, which is nearly of the same south latitude. 

 The coprophagous insects of New Holland seem indeed to 

 be principally composed of the genus Onthophagus or of 

 insects approaching to it, though even these occur but 

 rarely. This rarity of coprophagous insects in New Hol- 

 land is of course the natural consequence of that great 

 peculiarity of the Australasian continent, namely, the want 

 of all large herbivorous mammalia except of the marsupial 

 kind. Still I have little doubt but that if the marine de- 

 tritus of the coast of New Holland were properly searched, 

 we should acquire the knowledge of several insects ap- 

 proaching to Psammodii in habit. 





Fam. IV. TROGID^. 



Antennae hretes, novemvel decern articulis, basilari crasso ; 



