26 Annals Entomological Society of America [Vol. XV^ 



Over the base of the penis is the large hood-like pseudo- 

 sternite, the concavity of which forms a sort of sheath into 

 which the penis is retracted. The rami are not very distinctly 

 developed externally, though connected with one another 

 ventrally by a feebly chitinized arch. Their internal pro- 

 jections or endapophyses, however, are large and prominent. 



In the everted position, the penis of this species (PI. Ill, 

 Figs. 23, 24), protrudes considerably from beneath the pseudo- 

 sternite and the pocket beneath the ventral lobe is straightened 

 out. The spermatophore sac is obliterated and the parameres 

 appear as large divergent cornua, which as already stated, are 

 only feebly chitinized proximall}^ along their mesial surfaces. 



In this position Ceuthophilus illustrates well what appears 

 to be the primitive, dorso-terminal position of the parameres 

 in the Orthoptera. 



Fig. 26 is a posterior view of the end of the abdomen of 

 C. aridus Brun., in which the roof of the invaginated penis is 

 strongly retracted and folded ventrad in such a way as to 

 expose the under surface of the pseudosternite. This has been 

 forcibly elevated to show the lower margin, which is bent into 

 a little arch, beneath which the ejaculatory duct passes, cov- 

 ered also, of course, by the thin, collapsed roof of the penis. 

 Although this figure differs greatly in appearance from those 

 of C. lapidicola the genitalia are essentially similar in the two 

 species, as far as can be seen in the retracted condition. 



Fig. 27 is a similar view of C. macidatiis Harr., with the 

 genitalia everted. The parameres are very small and there 

 appear to be no openings on the roof of the penis. The pseudo- 

 sternite is a heavily chitinized gable-like structure, with a 

 median projection, and is prolonged ventrad into distinct rami. 

 It is quite suggestive of certain Gryllidas such as Gryllotalpa. 



The second type of genitalia differs from the first in the 

 following features: 



1. The absence of the pseudosternite, or its reduction to a 

 very slight membranous fold.* 



* A well developed pseudosternite, together with typical parameres, is figured 

 by Chopard ('20) in Thyreonotus corsicus Ramb., a Decticine. Chopard, how- 

 ever, regarded both structures as part of the "epiphallus." The case is important 

 in giving further conclusive evidence that the pseudosternite and parameres are 

 difTerent structures, a view that might otherwise be denied by those who would 

 fail to recognize as parameres the introversible processes of Ceuthophilus. 



