NO. 8 INSECT ABDOMEN — SNODGRASS 51 



The inner, or second, valvulae of Scudderia are narrow, closely 

 appressed blades (fig. 13 C, 2VI), upcurved between the broad third 

 valvulae. Their thickened bases are united medially with each other 

 (B, 2VI) and laterally with the inner faces of the basal valvifer areas 

 {sVlf) of the third valvulae. The lower edges of the weak inner 

 valvulae are strengthened by narrow sclerotic bands in their walls, 

 the proximal continuations of which, termed by Walker (1919) the 

 rami (fig. 13 B, C, ra), are united with a transverse intervalvular bar 

 (B, aiv) between the ventral margins of the second valvifers. From 

 the ramus of each inner valvula a sclerotic tongue extends upward in 

 the lateral wall of the valvula (C, pnvl) into the dorsal wall of the 

 common base of the two inner valvulae (A), and here the two from 

 opposite sides are confluent in a median stem that unites with a dorsal 

 intervalvular bar (piv). This Y-shaped dorsal sclerotization in the 

 base of the inner valvulae Walker (1919) calls the pons valvidarum 

 (pnvl). 



The dorsal and ventral intervalvular bars above mentioned (fig. 

 13 A, B, piv, aiv) are the ''superior intervalvula " and "inferior 

 intervalvula " of Walker (1919). These terms are appropriate in the 

 Tettigoniidae where one intervalvula is dorsal to the other, but the 

 sclerites both belong to the ventral wall of the ninth segment, and are 

 hence morphologically posterior and anterior, as they are anatomically 

 in Gryllidae (fig. 18, piv, aiv). For this reason the writer terms 

 the intervalvular sclerites the anterior intervalvula (aiv) and the 

 posterior intervalvula (piv), the first being the "inferior" interval- 

 vula according to Walker, the second the " superior ". The posterior 

 intervalvula of Scudderia bears a prominent median apodeme (fig. 

 13 A, C,^). 



The musculature of the ovipositor in Tettigoniidae and Gryllidae 

 is more complex than in Hemiptera and Hymenoptera. The dorsal 

 muscles of the eighth segment are inserted on the first valvifers ; 

 those of the ninth segment on the second valvifers, and on the inter- 

 valvulae, the first being tergopleural, the second tergosternal. Be- 

 sides these there are muscles connecting the first valvifers with the 

 second valvifers and with the posterior intervalvula. In Scudderia a 

 large bundle of fibers arises on the inner face of the second valvifer 

 and is inserted on the outer wall of the corresponding inner valvula 

 between the ramus and the arm of the pons. The musculature of the 

 ovipositor and the terminal segments of the abdomen will be fully 

 treated in the description of Grylliis assiniilis. 



The ovipositor of Gryllohlatta, judging from the descriptions of 

 Crampton (1917, 1927) and Walker (1919), is very evidently of the 



