1922] Walker: Structure of Orthopteroid Ifisects 31 



almost obsolete. The ectoparameres are broad, rounded and 

 prominent, and are closely connected with the endoparameres, 

 which are long, thin plates, extending forward almost to the 

 end of the spermatophore sac, and are wholly separate from 

 one another. They are lateral rather than dorsal in position, 

 being formed by an infolding of the integument on each side of 

 the spermatophore sac, whereas in Grylliis the infolding, though 

 partly lateral, is mainly dorsal, the two endoparameres coales- 

 cing in the middle line. In Oecanthus the entire endoparamere 

 is a chitinized plate, in Grylhis only the arcuate edges are chit- 

 inized. The anterior extremities of these plates in Oecanthus 

 are free and each bears a slender outwardly projecting spur. 



The spermatophore sac of Oecanthus is long and compressed, 

 but formed by an invagination similar to that of Gryllus. The 

 roof of the sac is, however, much longer than the floor, the 

 mouth being very oblique. The ventral lobes are similar to 

 those of Gryllus. 



In Gryllotalpa, according to de Saussure and Zehntner ('94) 

 the pseudosternite has somewhat the form of an anchor (hence 

 the term "anchre" of these authors), being produced laterally 

 into a pair of long arms which are evidently the rami. The 

 distal prongs are lacking in this genus. 



Tridactyloidea. Ripipteryx carhonarius Sauss. is the only 

 species whose genitalia were studied (PI. V, Figs. 47-50). On 

 first examination there appear to be no chitinous parts, as 

 these are almost wholly retracted, but in a cleared preparation 

 a structure of some complexity was revealed. This structure 

 is elongate and much depressed and consists of two flattened 

 sacs, dorsal and ventral, connected at their posterior extrem- 

 ities. The ejaculatory duct, which is distally rather wide, with 

 distinctly chitinized walls, opens into the anterior end of the 

 ventral sac, which thus seems to be the homologue of the 

 spermatophore sac. No trace of lateral glandular pouches is 

 present. The dorsal sac is covered with a thin plate, which is 

 little chitinized except along the lateral margins, which* are 

 produced cephalad into a pair of long, slender rods, apparently 

 for the insertion of muscles, and at its posterior extremity, 

 where there is a small plate or more heavily chitinized part of 

 the roof of the sac, which barely projects over the genital 

 aperture. The roof of the dorsal sac is evidently the pseudo- 

 sternite but is so deeply retracted as to be almost wholly an 



