87 
KEY TO ILLINOIS SPECIES OF ACRIDIDiE. 
This key is intended as an aid in determining species, without the 
necessity of determining the genera. The numbers at the right maj’gin 
following the names in parenthesis, refer to the number of the species 
given in the list which follows the key. The other figures, in the 
body of the key, indicate the usual length of the species in inches 
and decimals of an inch; m signifies male and f female. 
Sub-fam. ACRIDINAE. 
I. Face distinctly sloped under tower the breast; 
front of the head projecting before the eyes in 
the form of a blunt cone or pyramid. Group.— Truxalini. 
A. Prosternum armed with a spine; a brown stripe 
each side. ( M . bivittata.) 1. 
AA. Prosternum not armed with a spine. 
a. Sides of the pronotum and its lateral caring 
straight and strictly parallel. 
b. Antennae enlarged and flattened at the base 
in both sexes; elytra passing the abdomen; pro¬ 
notum rounded or obtuse-angled behind; fe¬ 
male much larger than the male, f 1.75; m 
1.10. (T 7 . brevieornis.) 2. 
bb. Antennae filiform in both sexes; elytra shorter 
than the abdomen; pronotum truncate behind; 
length about an inch. (Chloealtis.) 3 and 4. 
aa. Lateral carinae of the pronotum more or less 
curved or bent inward towards the middle. 
