584 Wisconsin Academy of Sciences , Arts , and Letters . 
I. 
The trophi of the Scarabaeidae show a remarkable adapta¬ 
tion even to slight differences in food habits. In no other 
order of the Coleoptera do we find so great an amount of vari¬ 
ation, and even slight, comparatively recent changes in habits, 
when once established, are followed by a decided modification 
of the mouth-parts. (Compare Aphodius fimetarius and A. 
granarius). 
Comstock (2) divides the order into two great groups, the 
scavengers and the leaf-chafers, each of which is further sub¬ 
divided. This grouping is based entirely upon habits and 
general external appearance, and, as might be expected, closely 
corresponds with a division based upon the form and develop¬ 
ment of the trophi. The arrangement given by Comstock is 
as follows: 
1. The Lamellicorn Scavengers 
A. The Tumble-bugs 
B. The Aphodian Dung-beetles 
C. The Earth-boring Dung-beetles 
D. The Skin-beetles 
2. The Lamellicorn Leaf-chafers 
A. The May-beetles or June-bugs 
B. The Bose-bugs 
C. The Shining Leaf-chafers 
D. The Rhinoceros-beetles 
E. The Elower : beetles 
These may be taken up in the above order. 
1. The Scavengers. These live either in dung or on decay¬ 
ing animal matter, their mouth-parts showing in general the 
following characteristics: 
a. A well developed gustatory sense, which is represented 
by the more or less prominent epipharyngeal and hypopharyn- 
geal structures. 
h. Mandibles which show distinctly their origin from a 
number of segments, and are characterized by the presence of 
a distinct conjunctivus. 
