50 Annah Entomological Society of America [Vol. XV, 



margin. The genital cavity is much smaller than in the Blat- 

 tidae and contains no chitinized parts. In neither of the forms 

 could I find a penis of any sort, merely a median genital aper- 

 ture with membranous walls. The absence of external genitalia 

 is without doubt a secondary condition. The points of resem- 

 blance to the Blattids and Mantids are so numerous as to 

 leave no doubt that the Isoptera are closely related to them, 

 and this belief carries with it the assumption that external 

 genitalia were present in the common ancestor of these groups. 

 The genitalia of this ancestral form were probably asymmet- 

 rical, since they are of this type in Gryllohlatta, a form that is 

 somewhat more primitive than the members of the other 

 three groups. 



Zoraptera. 



An interesting paper by Crampton on the external anatomy 

 of Zorotypus hubbardi Caudell has recently appeared (Cramp- 

 ton, '20), in which some details of the terminal segments of 

 both sexes are given. The general appearance of these segments 

 recalls the Isoptera, to which order Crampton regards the 

 Zoraptera as nearly related, and it is stated by this writer that 

 **the terminal segments in general and of the winged females 

 in particular are quite Isopteroid." He does not specify in 

 what respects they are Isopteroid, and a study of his figures 

 does not confirm the statement. The ninth tergum in both 

 sexes is much reduced and bears a horn-like projection in the 

 male; the tenth appears to form with the supra-anal plate and 

 paraprocts a continuous sclerite. The cerci are short and 

 unsegmented. 



More important than these, however, are the sternal char- 

 acteristics. The ninth sternum of the male, so conspicuous in 

 the Isoptera, is seemingly absent or represented only by a 

 membranous lobe, while the eighth, according to Crampton's 

 figure, takes the place of it as a subgenital plate. In the 

 female the eighth sternum is well developed, not reduced and 

 concealed by the seventh as in the Isoptera, Blattids and 

 Mantids, while there is an additional sclerite below the anus, 

 not represented in these groups. 



The male genitalia (Figs. 78-79) resemble those of the 

 Mantids, as pointed out by Crampton. The sinistral process 

 appears to be the same as that which I have considered to be 



