Hardenberg—Studies in the Trophi of the Scarabaeidae. 589 
crease in chitinization until in Trichius we again find a free 
projecting epipharynx which shows in its general shape and 
the distribution of its sense-papillae and hairs a close resem¬ 
blance to that of the Copris-heetles. That the gustatory sense 
is here more highly developed than in the typical pollen-eating 
forms may possibly be explained by the habits of the insect ; 
it is said that it dives deep into the flower and eats the soft 
inner part; possibly the fact that the nectaries form part of 
its food may account for the greater development of the gusta¬ 
tory sense in this insect. 
Mandibles. In the Copns-beetles we find the mandibles 
composed of a number of sclerites, the molars well developed, 
that of the left mandible concave, that of the right convex. 
The galea is membranous with a fringed edge; the lacinia is 
well developed, with a distinct conjunctivus. At the junction 
the conjunctivus bears a tuft of hairs, different in shape from 
those which fringe the edge of the lacinia. Subsequently the 
lacinia becomes longer until it nearly attains the tip of the 
galea. The galea now becomes more chitinized, its fringe dis¬ 
appears and is replaced by one or more chitinous teeth. This 
chitinization also involves the outer margin of the lacinia, and 
this sclerite, at least in some cases (as in Geotrupes ), takes 
part in the formation of the tooth or teeth of the mandible. 
As chitinization proceeds further, the hairy fringe indicating 
the position of the lacinia becomes shorter and the conjunc¬ 
tivus less prominent, until at last neither can be distinguished, 
and there is only a whorl of hairs between the molar and the 
chitinized, toothed part of the mandible. This whorl of hairs, 
which is generally conspicuous, indicates the place of junction 
between the original lacinia and conjunctivus. The lacinia 
evidently becomes chitinized and fuses with the galea, forming 
part of the teeth. This is the condition in Trox and the leaf- 
chafers, for here strong mandibles are needed for cutting and 
grinding tough material. Coming to the flower-beetles, a re¬ 
duction in chitinization is found; the molars become smaller; 
the galea becomes long and membranous at the tip, the lacinia 
broad and entirely membranous. In some cases this mem- 
