282 Annals Entomological Society of America [Vol. XII, 



The inner valvulae are extremely vestigial and quite mem- 

 branous. They project backward from the lower part of 

 the superior intervalvula. They were overlooked by Lacaze- 

 Duthiers (loc. cit.), who mistook the dorsal valvulae for them, 

 owing to their close connection with the inferior intervalvula, 

 which is suggestive of the connection in many Tettigoniidae 

 between this plate and the rami of the inner valvulae. 



In Oecanthus (Figs. 16-18, Oe. quadripunctatus Beut.) the 

 genitalia do not differ from those of Gryllus except in com- 

 paratively unimportant details. The most striking feature is 

 the exceedingly powerful ninth tergal apodeme, which forms a 

 complete arch around the base of the tergite ; and the otherwise 

 feebly chitinized dorsal surface of segments 9 and 10. These 

 features are doubtless related to the habit of the genus of ovi- 

 positing in woody stems, which would require a greater develop- 

 ment of the muscles of the ovipositor than is necessary in such 

 ground-dwelling species as Gryllus assimilis. 



The dorsal and ventral apophyses and the ventral pro- 

 longation of the valvifer are also longer than in Gryllus. 



The general proportions of the abdominal segments and 

 terminal structures are somewhat suggestive of some Tetti- 

 goniidcB and of Grylloblatta, but there are no indications of 

 relationship with the latter form, as has been more than once 

 suggested by Crampton, who has been apparently influenced 

 by superficial resemblances of form. As far as the terminal 

 abdominal structures are concerned, Oecanthus is more special- 

 ized than Gryllus, and if anything even less like Grylloblatta 

 than the latter genus is. 



Acridoidea (Acrididse, Acrydiidse). 



The appearance of the ovipositor in this superfamily is 

 singularly different from that of the two preceding groups, but 

 the fundamental similarity of its structure in all three was 

 demonstrated long ago by Lacaze-Duthiers ('52, loc. cit.) and 

 Graber (70) ^^ Its peculiarities in the Acridoidea are chiefly 

 modifications connected with the different method of oviposi- 

 tion. The dorsal and ventral valvulae function as a pair of 

 forceps for digging the hole, usually in the ground, in which the 

 eggs are deposited. Each pair of valves acts as one of the 



" Graber, V., Sitzb. K. Akad. Wiss., Bd. LXI, Abtl. 1, pp. 597-616, 1 PI. (1870). 



