17 



when the prosternum is without a spine it is smooth or unarmed (as Tryxalis, 

 Pyrgomorpha, and the entire groups CEdipodlni and Tettigini). This spine is 

 either subcyhndrical or cuneiform, obtuse or acute, straight or curved, &c. ; 

 these differences furnishing either generic or specific charaters. Those species 

 without the prosternal spine generally have the prosternum marked with a 

 transverse curved groove more or less distinct. 



The mesosternum is the broad piece of the under side that lies between 

 the middle legs, and is marked with one or more indentures. It varies 

 slightly in form, and may be used in describing species, though I believe this 

 has not been done except in a few instances in Fischer's Ortlioptera Europea. 

 The pieces in front of the middle legs, extending obliquely up the sides, are 

 the episterna of the mesothorax; the pieces situated externally to and adjoin- 

 ing the insertion of the middle legs are the epimera of the mesothorax. 



The metasternum is the under surface of the metathorax, and is situated 

 between the bases of the hind legs, and is usually marked with a single or 

 double indenture in the middle. The episterna and epimera of the metathorax 

 correspond very nearly in relative position with those of the mesothorax. 



These thoracic rings on their internal face furnish support for the strong 

 muscles necessary for the vai'ious movements of the wings and legs ; and if 

 we strip them of their appendages, and cut off the posterior projection of the 

 pronotum, limiting it to the length of the prothorax, we will at once see that 

 they are true homologues of the abdominal segments, changed from the 

 typical form only so far as is necessary for the support and operation of the 

 organs of locomotion. 



The legs, as in other insects, are divided into several parts or joints as 

 follows : The coxa (Fig. 2, ex) is the basal joint by which the leg is connected 

 to the body; it is short in Acrididce, but is usually enlarged. The trochanter, 

 which is the next joint, is small, and can be best seen in the anterior pair of 

 legs. The third piece or joint is the thigh (femur), and is the largest portion 

 of the leg (Fig. 2, fm). The fourth piece is the tibia or shank (Fig. 2, tb), 

 and is attached to the tip of the femur. The terminal portion, which rests 

 upon the ground, is the tarsus or foot (Fig. 2, tr), and is composed of three 

 joints; the first, or basal, and the third (or terminal) joints being longer than the 

 second (or middle) joint. The first has two transverse indentures on the 

 under side, which give it the appearance, when seen on this side, of being 

 three pieces, thus making the tarsus appear five-jointed; l)ut seen from above, 

 3 A • 



