288 Annals Entomological Society of America [Vol. XII, 



guide. The basivalvulae are of enormous size and have the 

 appearance of a divided subgenital plate, for which they were 

 mistaken by de Saussure and Zehntner. 



The ovipositor as already noted, is essentially Acridian in 

 type. The dorsal and ventral valvulse are sigmoid in form, 

 the apices of the dorsal valvulae curving upwards, the ventral 

 pair terminating in sharp, decurved hooks, and having also 

 a shorter external hook (cf. Melanoplus, Figs. 22, 23). In 

 de Saussure and Zehntner's Figure (1. c, PI. XVII, Fig. 27) 

 what is evidently the same hook is represented as belonging to 

 the dorsal valvulae, but this is certainly an error, due to the 

 valvulas having been tightly closed in the specimen drawn. 

 As in most Acridoidea there is no trace of the valvifer, while 

 the free chitinous rod (pap) is represented by a prominent, 

 shelf -like apodeme (ap 9), extending from the angle between 

 the valvulae along the ventral edge of the ninth tergite and 

 projecting a short distance under the eighth. This ridge is 

 quite similar in relation to the valvulae to the free rod of the 

 Acridoidea, but is a true ninth tergal apodeme, like that of the 

 Gryllidae and Tettigoniidae. It is in this feature that the 

 genitalia of the Tridactylidas differ most from those of the 

 Acridoidea. 



The dorsal valvulas, as in the Acridoidea, lack distinct 

 superior apophyses. The superior and inferior intervalvulae 

 have precisely the same positions as in that group, but are 

 even smaller and simpler in form. The inferior intervalvula 

 is a slender transverse bar resembling that of Gryllus in form 

 and is connected at its outer ends, separately, with both the 

 small inferior apophysis and the rami of the inner valvule. 

 The latter are, as in the Acridoidea, very small, but lack the 

 intervalvular membrane and pons. 



There are many other points of resemblance between the 

 Tridactylidas and Acridoidea, and taking all these into con- 

 sideration, we can hardly doubt that the nearest relations of the 

 former are the Acridoidea rather than the Gryllidae. 



