50 Psyche [June 



the callosity labeled "c" in Fig. 17, as the remains of the cercus 

 (which appears to be lost, or vestigial in most Neuroptera), and the 

 spine-like process "g" as the homologue of the gonopod "g" 

 of ChavUodes (Fig. 10), although I am not sure that these inter- 

 pretations are correct, until other material has been examined to 

 determine these points. The Psocidas seem to be as closely re- 

 lated to the Neuroptera as any of the lower insects, and may be 

 regarded as annectent between the Neuroptera and the Embiid 

 Plecopteron group, from which have also branched off the Isoptera 

 to which the Psocids are likewise closely related. 



It is impossible to draw any definite conclusions concerning the 

 relationships of the different Neuropteroid insects from a study of 

 the genitalia alone; but the following points of similarity of 

 structure in the different groups may be noted. In the Sialid 

 group (Figs. 2, 4, 10, and 15), the hypandrium, or subgenital valve 

 "hy " is comparatively small, and the gonopods "g" with the para- 

 procts "pa" are usually represented, although they are not always 

 well developed. The anal tubercle orproctiger "ap" is present in 

 most of this group, while the supraanal plate is usually wanting. 



lihone (Fig. 14) is considered as one of the most primitive 

 representatives of the Neuroptera-Planipennia, and presents 

 certain features suggestive of the condition found in the Sialid 

 group. In the dried specimen of Ithone here figured (Fig. 14) 

 there appeared to be a somewhat shriveled anal tubercle or proc- 

 tiger "ap." The structures labeled "g" in Fig. 14, are not very 

 like the gonopods "g" of the Sialid group (Figs. 10 and 15); 

 but resemble somewhat more closely the structures labeled "g" 

 in the Myrmeleonidae (Fig. 7) which have been provisionally 

 homologized with the gonopods. The penis hooks "pu" of 

 Ithone (Fig. 14) are quite unlike those of the other forms here 

 shown, and are covered by an arched roof-like structure. The 

 hypandrium or subgenital plate "hy" is well developed in Ithone, 

 unlike the condition occurring in the Sialid group. 



Polystoechotes (Fig. 8), which is one of the Planipennia, has no 

 well developed hypandrium "hy," and a structure labeled "co" 

 in Fig. 8, may possibly represent the columna "co" of the Sialid 

 group (Fig. 10). If this is correct, the terminalia, or terminal 

 abdominal structures of some Planipennia are not unlike those of 

 certain Sialids. In Nemoptera (Fig. 12), another of the group 



