ON DECOMPOSED VEGETABLE MATTER. 6l 



both infundibuliform, so that the whole becomes to the 

 naked eye united under the form of a globular mass. 

 Again, from the Scarabceidce, Aphodiida, and Dynastida, 

 the Trogidcz are generally to be distinguished by their 

 exserted labrum. This family of all the Saprophagous Peta- 

 locera appears to contain the fewest species, and moreover 

 seems to be distributed in nearly equal portions over the 

 tropical and temperate climates. Another peculiarity 

 attending it is, that it contains apterous insects, which 

 are unknown as yet among all the other families of Peta- 

 locera. 



If the observations of the more modern entomologists 

 are altogether to be relied on, the economy also of the 

 Trogidce differs in some cases considerably from that of 

 the other Petalocerous insects. As, however, this is a ques- 

 tion by no means decided and rather interesting, I shall 

 enter briefly into the discussion of it. 



The genus Mgialia is found upon the seashore with 

 the Psammodii, to which it bears so remarkable an affinity ; 

 and in all probability lives with these insects on putrid 

 seaweed, or other marine detritus. The genus Acantho- 

 cerus, the type of which appears to be Trox spinicomis, 

 Fab., cannot, any more than Mgialia, be considered to feed 

 on the dried carcases of animals, as the slight construction 

 of its mandibles and membranaceous maxilla? must render 

 it altogether unfit to live on any but the most soft -and 

 pulpy substances. Trox horridus of Fabricius, which is 

 distinguished from most others of the original genus by a 

 triangular labrum, and by its body being apterous and 

 elytra connate, I have separated from the rest, under the 

 generic appellation otPhoberus. This insect, as I conceive, 

 does not feed on dried cadaverous substances; because it 



