1922] Walker: Structure of Orthopteroid Insects 29 



the spermatopbore sac, as can be seen clearly in transverse 

 sections. From their muscular connections they appear to 

 represent the bases of the parameres, and may be termed 

 endoparameres (Fig. 37, pmb). With the parameres may 

 also be associated the lateral bars already mentioned, and 

 perhaps also the two lobes supported by triradiate sclerites, 

 which are situated just beneath the lateral prongs of the pseudo- 

 sternite, and which are also in close connection with the lateral 

 bars (ectoparameres, Figs. 38, 39, pm). 



At first sight it would appear as though the spermatophore 

 sac were the homologue of the paramere sac of the Tettigonoidea, 

 but the latter structure is developed merely as a result of the 

 enlargement and inward extension of the paramere bases, in 

 consequence of their function as protrusible titillators, whereas 

 in the Gryllidae the parameres possess no such modification and 

 have no bases other than the roof of the spermatophore sac itself. 



The paired glandular pouches, which open into the ejacu- 

 latory duct near its termination, are similar to those of most 

 Tettigonoidea, though somewhat smaller. 



The last nymphal stage of Gryllus shows some peculiar 

 features. Figs. 40 and 41 are ventral and ventro-posterior 

 views of the genitalia at this stage. The pseudosternite 

 resembles that of the adult, except that its three prongs are 

 very short and blunt. The ventral lobes appear as a flat, 

 bilobed, chitinous flap, covering the site of the genital aperture, 

 which has not yet appeared. Between the pseudosternite and 

 the ventral lobes is the space that later becomes invaginated 

 to form the spermatophore sac. The chitinous layer which 

 lines the latter, and also the median groove and the two terminal 

 points are already indicated, the last-named structures being 

 relatively much larger and stouter and not yet separated into 

 two parts. They are separated from the pseudosternite by a 

 larger space than in the adult. There is at this stage no indica- 

 tion of the parameres. 



It may be questioned whether the structures which I have 

 identified as the parameres are the true homologues of these 

 processes in the Tettigonoidea. They are the structures 

 called "titillators" by de Saussure and Zehntner, while Chopard 

 refers to them as the underside of the "pseudepiphalle" (pseudo- 

 sternite) and recognizes no homologues of the titillators or 

 parameres ("epiphallus"). My reasons for identifying these 



