NOTES ON INSECTIVOROUS COLEOPTERA. 
By S. A. FORBES. 
Mouth Structures of Carabjd^. 
In studying tlie food of birds, I found it necessary to 
construct a key to tlie genera of the Carabidae, based pri- 
marily upon the mouth structures, and prepared for this 
purpose a large number of slides of the mouth parts of 
Illinois species. In studying these, two characters were 
noted, which proved to be of considerable service for 
classification. The first of these is the frequent oblitera- 
tion of the suture between the mentum and the gula 
(called the “gular suture”, by Dr. LeConte, in his Classi- 
fication, Pt. I, pp. X, XIII, 14, 15 and 16), the mentum 
being, in such cases, connate with the gula. This is true 
of Bleclirus, although in Trechicus and Metabletus of the 
same group the suture is distinct. The mentum is again 
connate in many species, at least, of several genera of 
Papti and Eurytrichi ; viz., Geopinus, Anisodactylus, 
Xestonotus, Spongopus and Amphasia; but is not con- 
nate in Nothopus, Piosoma, Discoderes or Anisotarsus. 
This character was noticed nowhere else except in Amara 
cingustata, which differs in this respect from all the other 
Amarae m the Laboratory collection. This species is also 
peculiar in the very great development of the muscular 
ridges on the upper surface of the mentum. In the Lebiae 
this mental suture is distinct in the middle but obsolete 
at the ends. 
The second character referred to is found in the stipes 
of the maxilla. This body is covered with three plates — 
an outer, closely connected with the palpus, a lower, from 
which the two lobes of the maxilla spring, and an upper 
plate, which is applied to the under surface of the mandi- 
ble. The last of these usually presents, in the Harpalidae, 
a more or less prominent angle at about the anterior third 
of the outer margin, although this margin is sometimes 
regularly curved. In two genera, Agonoderus and Sten- 
