1935 ] 
Structure of the Pretarsus 
13 
Order Hemiptera 
Brochymena arbor ea (Say) (Fig. 15) 
The large triangular unguitractor is extended anteriorly 
to form a quadrate empodium which bears a parempodium 
on each of two lateral protuberances. Beneath the claws 
are pad-like structures (pv?) reinforced by chitinous plates 
but not attached to the claws beyond their bases in con- 
trast to the condition in Membracidae, Cicadellidae, etc. 
Although it seems very probable that these pads will prove 
to be identical with those of the Homoptera, but separated 
from the claws, it is more questionable whether they can be 
considered as homologous to the pulvilli of higher orders 
especially because of the fact that typical basipulvilli do not 
appear in the Hemiptera-Homoptera. The condition in 
these groups, however, possibly indicates a way in which 
sub-ungual pads may be developed and split off from the 
claws. Further reduction of the membranes might result 
in the typical pseudarolia of the Mirids! It is hoped that 
an extensive study of the Hemiptera-Homoptera will illum- 
inate the relations of these various structures. 
Order Coleoptera 
Phyllophaga fusca Froe. (Fig. 16) 
As mentioned above, the empodium, rather than basipul- 
villi and planta, is the characteristic feature of Coleoptera. 
In this specimen the unguitractor is narrow and the em- 
podium is expanded distally into a broad plate which bears 
two parempodia or large setae. Each claw is provided with 
a large median tooth. 
Hayes and Kearns have figured many specimens from 
this order and although they find the empodium absent in 
many cases, there seems to be a typical fundamental plan 
for the coleopterous pretarsus. That is: First, a well de- 
veloped unguitractor with or without some form of em- 
podium which in turn may or may not bear parempodia; 
Second, total absence of any membranous structures which 
could represent arolia, pulvilli, etc. Hayes and Kearns find 
that “some cleared specimens show what appears to be a 
basal part of the empodium withdrawn into the body of the 
