18 Annals Entomological Socieyt of America [Vol. XV, 



Orthoptera. 



In the Orthoptera there is a tendency toward a shortening 

 of the posterior terga, which is most marked in the Acridoidea, 

 while the anal plates are usually well developed but very variable 

 in form. The supra-anal plate is frequently fused with the 

 tenth tergum, but not overlapped nor replaced by the latter as 

 in the Blattoidea, Mantoidea and Isoptera, although in certain 

 Tettigonoidea (Ceuthophilus) the ninth tergum (more rarely 

 the 8th) projects over the tenth and supra-anal plate, thus 

 having the appearance of being the last dorsal segment. The 

 cerci are with rare exceptions unsegmented and short, being 

 frequently modified as claspers. A small cereal basipodite is 

 usually present. The ninth sternum is generally entire, 

 forming a hypandrium, but in the Acridoidea it is divided by a 

 transverse suture, as in the Phasmoidea, the distal plate 

 probably representing the fused coxites. Secondary sub- 

 divisions may also occur in some Tettigonoidea. In this super- 

 family styli are generally present, but they are absent in all the 

 other groups. 



Owing to the peculiar and often extremely complex structure 

 of the genitalia it will be convenient to deal with these separately 

 after having discussed the other structures with which we are 

 concerned. 



The Terminal Segments, Cerci and Styli. 



Tettigonoidea. In most of the long-horned grasshoppers 

 the abdominal segments are not greatly specialized, the terga 

 and sterna being distinct and separate, the latter rather feebly 

 chitinized, and the spiracles occupying the pleural membrane. 

 There is usually relatively little shortening of the 9th and 10th, 

 although sometimes, as in Ceuthophilus, the 10th is small, 

 subvertical and concealed by the projecting 9th tergum, 

 which is thus commonly but erroneously termed the supra-anal 

 plate by systematists. The true supra-anal plate is of variable 

 size, but generally inconspicuous, and frequently fused with the 

 tenth tergum in the adult insect. It is not divided trans- 

 versely, or otherwise, as in many Acrididae. The paraprocts 

 are commonly lobe-like and but little chitinized. The ninth 

 sternum is typically undivided, though indications of the 

 coxites are sometimes seen in the more or less bifid caudal 



