12 Annals Entomological Society of America [Vol. XV, 



to their apices. Retraction of the penes is accompanied by 

 the distal part of the parameres. 



In this species there is also a sclerite (vo) resembling the 

 "subanal vomer" of the Phasmoidea, consisting of a transverse 

 band of chitin immediately in front of the paraprocts, which 

 is elevated in the middle into a rounded shelf-like projection. 

 On each side the chitin is expanded into a thin plate, which 

 extends to the basal portions of the parameres. In Blasturus 

 nebulosus (PI. I, Fig. 3) and B. cupidiis each penis bears a single 

 hook arising ventrally near the apex and curved proximad. 

 These have been termed " subappendiculae " by Crampton, but 

 they appear to represent the distal parts of parameres. Para- 

 meres have also been described in Heptagenia venosa by Pey- 

 toureau ('95) who termed them "aiguillons. " In other genera, 

 such as Hexagenia, they are wholly absent. 



Dermaptera. 



In the Earwigs the large forcipate cerci are associated with 

 modifications of the neighboring sclerites, although the penis 

 retains an apparently primitive structure. The only exception 

 is the aberrant parasitic form Hemimenis talpoides Walk., in 

 which the cerci are simple and styliform. Segmented cerci 

 occur in the immature stages of Dyscriti?ta and Diplatys, 

 (Burr, '11, Zacher, '11), a fact that indicates the more primitive 

 nature of this type of structure. 



Correlated with the unusual development of the cerci is the 

 enlargement of the 10th tergum, but there is no marked 

 abbreviation of two preceding terga, such as occurs in the 

 females, and all the terga are free. The 9th sternum is well 

 developed, undivided and without styli. The paraprocts and 

 so-called " opisthomeres " or segments of the supra-anal plate 

 are similar to those of the female. The latter may vary in 

 number from two to four, and as the larger numbers occur 

 only in primative genera, it would appear that they are part of the 

 expression of this primitive condition. They cannot be con- 

 sidered as vestigial metameres, as there is no evidence for the 

 existence of more than eleven true metameres in the abdomen 

 of any insects, but they may possibly represent the vestige of a 

 jointed, caudal filament, like that of the Ephemerida. 



In the superfamilies Protodermaptera and Paradermaptera 

 the penis is double or deeply bipartite, the two ejaculatory ducts 



