1922] Walker: Structure of Orthopteroid Insects 5 



of the Ephemerida there is a somewhat similar plate, but it 

 appears to be exceptional in this order; while in the Orthoptera 

 a somewhat analogous structure, clearly belonging to the same 

 intersternal membrane, is found in a majority of the species. 

 It functions, however, not as an anal valve, but as a part of the 

 genitalia. This is the part I have called the pseudosternite. 

 It has been confused by various writers with the "epiphallus" 

 or "titillators" (parameres). Crampton ('18), e. g., identifies 

 this structure in the Acrididce and Gryllidse with the "epi- 

 phallus" or parameres of the Tettigoniidae, and Chopard ('18) 

 makes the same error with regard to the Acrididse, but in the 

 Gryllidae he considers it a distinct structure, which he terms the 

 "pseudepiphalle. " In the latter family it has also been termed 

 the "anchre" by de Saussure and Zehntner ('94) in the genus 

 Gryllotalpa, on account of its anchor-like form in that genus. 



Various other structures concerned in copulation are fre- 

 quently present. Claspers may be developed from the cerci 

 (Dermaptera, Odonata, many Orthoptera) ; the coxites, or 

 coxites and styli (Grylloblattoidea, Ephemerida) ; the para- 

 procts (Odonata Zygoptera, some Orthoptera of the family 

 Tridactylidas) ; titillators, copulatory hooks and similar append- 

 ages appear upon a great variety of structures, e. g., the 9th 

 sternum (Embiidina, some Blattoidea) ; the 10th tergum 

 (Embiidina, Grylloblattoidea, some Plecoptera) ; the supra-anal 

 plate (some Plecoptera) ; the paraprocts (some Plecoptera and 

 Blattoidea, a few Orthoptera of the family Tridactylidse) ; the 

 left cereal basipodite (some Embiidina) ; and finally from the 

 vicinity of the genital aperture, including the pseudosternite, 

 the parameres and the penis itself (Dermaptera, Ephemerida, 

 Blattoidea, Mantoidea, Orthoptera, etc.) 



Other chitinous structures are present in particular groups, 

 the most noteworthy of these being connected with the develop- 

 ment of the spermatophore sac in the Orthoptera. These 

 will be considered in the account of this order. 



The terga and sterna of the terminal abdominal segments in 

 Orthopteroid insects are also subject to considerable variation 

 apart from that of the more essential genitalic structures, 

 some of these modifications being similar to those found in the 

 females of the same species. Thus we find that in the Orthop- 

 tera the supra-anal plate is nearly always well developed in 

 both sexes, while in the Blattoidea, Mantoidea and Isoptera 



