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 Chauliodes (Fig. 10), although I am not sure that these inter- 
pretations are correct, until other material has been examined to 
determine these points. The Psocidez 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 or proctiger “ap” is present in 
most of this group, while the supraanal plate is usually wanting. 
Ithone (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 Jthone 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 Myrmeleonide (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 
