38 



PROCEEDINGS OF THE ACADEMY OF 



[Jan. , 



Fig. 19. 



Figs. 19, 20 and 21.— ^Represent the ventral and lateral sclerites of a segment 

 of the Cursoria (Orthoptera) spread out in one plane. Fig. 20 represents a 

 hypothetical starting point in the formation of the pleural and sternal sclerites 

 of these insects. The dotted lines indicate where divisions may occur. Fig. 

 19 represents the modification found in the Forficulidae, and Fig. 21 that 

 found in the Blattidae. The diagonal lines in the basi-sternum (fig. 21) illus- 

 trate the condition found in the prothorax of Ectobia. 



