12 
Psyche 
[ March 
be set off from the Blattid group on the one hand, and the 
remainder of the orthopteroid insects on the other. (Speak- 
ing from the standpoint of pretarsus only, of course). The 
unguitractor of Psalis is interesting because of its anterior 
projection (em?) which could be considered either empo- 
dium or planta; superficially, this structure appears to be 
continuous with the unguitractor and therefore more like 
a coleopterous empodium except that its margins are vague 
and it is not heavily sclerotized, i. e., more like a planta. It 
should be noted and may prove to be significant that all 
examples of Coleoptera thus far observed show neither 
basipulvilli nor planta but do have an empodium, whereas 
all specimens of most higher orders studied are fundamen- 
tally of the Blattid type with numerous secondary special- 
izations. 
Order Homoptera 
Agallia constricta Van Duzee (Fig. 14) 
The small unguitractor bears a triangular empodium 
(em) which in turn is provided with a single heavy seta or 
parempodium (pern). As there seems to be considerable 
variation in the number of setae and in the shape of the 
empodium among the Homoptera, this group must be more 
fully studied to determine the extent and constancy of such 
variations. Attached to the under surface of the claws and 
extending beyond their tips are large membranous pads 
(pv?) which are reinforced meso-dorsally by small sclero- 
tized areas. There are no basipulvilli. 
The pretarsi of Cicadidae are not of this type nor do 
they show any features characteristic of the more advanced 
Hemiptera. As figured by Snodgrass (1927) the ungui- 
tractor of T. septendecim is divided into two plates; there 
is no empodium, but two small setae-bearing sclerites occur 
in the membrane between the claws, and Snodgrass sug- 
gests that these may represent the arolium but there seems 
to be more reason to consider them as a divided planta. In 
T. cinera these plates are very faint and difficult to distin- 
guish from the surrounding membrane. There are no pads 
beneath the claws. 
