588 Wisconsin Academy of Sciences, Arts, and Letters. 
a leaf-like expansion, often membranous; in the last member 
of the series (Valgus), the galea again ends in a hairy fringe. 
Thus this group, both in the greater development of the epi- 
pharynx and in the shape of the mandibles, betrays a similar¬ 
ity to the Copris-like forms, a similarity which would seem to 
indicate a close relationship. 
c. In the labial structures, however, there is shown a fur¬ 
ther development of the relations which exist in the preceding 
group (the leaf-chafers). The mentum has been pushed in 
still further over the sub-mentum, and the anterior plate of 
this sclerite has now become larger than the posterior one. 
II. 
Tracing the modifications within the order of the various 
organs in question, the following changes may be noted: 
Epipharynx. This organ is conspicuous in the Copris- 
beetles, in which it forms a highly specialized structure clearly 
showing its origin as a fold of the membranous roof of the 
mouth. Its attachment is at first far back at the caudal edge 
of the supporting arch, the latter being a stiff, chitinous struc¬ 
ture, which is here necessary to support the large, ^ projecting 
organ. The place of attachment moves forward, and, as the 
free, projecting part of the epipharynx becomes shorter and 
shorter, a strong supporting arch becomes unnecessary and dis¬ 
appears. At last the place of attachment has reached the front 
edge of the labrum, whose under surface is now formed by the 
epipharynx. An increase in chitinization now occurs, which, 
beginning at the front and lateral edges, proceeds inward, 
making the membranous part smaller and smaller until the 
whole epipharynx is chitinized (as in the leaf-chafers). With 
an increased chitinization goes a corresponding decrease in 
function; the sensory apparatus becomes less and less pro¬ 
nounced, until in the leaf-chafers it has entirely disappeared. 
In the flower-beetles we again see an increase in the de¬ 
velopment of the epipharynx, the reappearance taking place in 
the reverse order; that is, the sense-papillae, which were the 
last to disappear, are the first to reappear, followed by a de- 
