1918] Thoracic Sclerites of Dissosteira 355 



or basanale is situated at the base of the anal veins, and artic- 

 ulates with a posterior process of the notum which may become 

 detached to form an intermediate plate "a" called the adanal 

 ossicle. 



The Mesopleuron. 



Beneath the wing, at its base, are several alar ossicles which 

 are apparently of a pleural origin, or were formed in the region 

 largely belonging to the pleuron. These have been called the 

 alaria, in contradistinction to the pteralia which are tergal 

 ossicles. The two anteriormost of these ossicles "ba2," called 

 the basalar ossicles, are situated at the base of the wing, imme- 

 diately in front of the dorsal neck-like prolongation of the pleural 

 region serving as a ventral pivot for the wing in the movements 

 of flight. Immediately above this pivot, is the intralare "ia2," 

 and just behind it is the suhalar ossicle "sa2." 



The greater part of the mesopleural region is composed of 

 the epimerum "em2" and the epistermim "es2," which are sep- 

 arated by the pleural suture extending in an approximately 

 vertical line from the wing base to the coxal region. Extending 

 along the anterior margin of the region "es2" is a narrow sclerite 

 "pr2" called the prepectus, and in the upper portion of the 

 episternal region "es2" a small area labeled "ae" is marked off 

 by a faint suture. Ventral to the episternum and epimerum a 

 pericoxal sclerite "pc" extends around the base of the coxa, and 

 encloses the small sclerite "tn," which is all that remains of 

 the much reduced trochantin. 



In the membranous "intersegmental region" between the 

 prothorax and mesothorax is the first thoracic spiracle "s." 

 This spiracle has been attributed to the prothorax, but from the 

 standpoint of embryology, it is mesothoracic, since it has its 

 embryonic origin in the anterior region of the mesothorax and 

 later migrates into the "intersegmental" region (which is also 

 largely mesothoracic). 



The Leg. 



As in most Orthoptera, the bases of the . legs are widely 

 separated. The pericoxal sclerite "pC2" encircling the base of 

 the coxa (Figs. 1 and 2) seems to be peculiar to the grasshopper 

 group, since I have been unable to find it in any of the crickets, 

 mole-crickets, or katydids which I have examined. The pleural 



