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June, 1918 Bulletin of the Brooklyn Entomological Society 5d 
able importance from the systematic standpoint ; but they have not 
been used very much in keys, due, no doubt, to the fact that they 
are not easily seen from without. 
The homologies of the titillator are not easily determined. 
Some investigators would compare this structure to the parameres 
of lower forms. In the Neuroptera such as the one shown in 
Fig. 100, I think that the structure “ep,’ usually termed the 
“penis,” is really the titillator. The columna labeled “co” in 
Fig. 100 may possibly be the homologue of the structure desig- 
nated by the label “pe” in the Plecopteron shown in Fig. 17. I 
have not the necessary intermediate forms, however, to determine 
these and other points of interest, and the lack of this material 
has proved to be a great handicap in the present study of the 
phallus. I would therefore greatly appreciate the loan of any ma- 
terial which anyone might deem suitable for this purpose, since 
my own collection is too meagre to permit of an extended study 
of intermediate forms necessary to determine many of the points 
in question. 
In certain Blattids, such as those shown in Figs. 97 and gg, 
there occur two prong-like processes labeled “sh,” which appear 
to be portions of the paraproct “pa.” One of these prongs in 
the roach shown in Fig. 99, “sh,” projects downward into the 
region of the phallus, while the other prong (the one located 
on the sinistral side of the body) has become reduced in size, and 
is more closely united with the paraproct region “pa.” In the 
roach shown in Figs. 80 and 81, the sinistral prong has disap- 
peared, while the dextral one “sh” of Fig. 81 is closely united 
with the paraproctal region “pa” of Fig. 80. 
Since the structure called the vomer “v” in certain Phasmids 
(Figs. 51 and 62) is rather closely associated with the paraproctal 
region “‘pa,” this suggests the possibility that the vomer “v” 
(Fig. 51) may represent the united prongs “sh” of the roach (Fig. 
97). The prongs of the titillator (Figs. 73 and 76 “ep”) are 
usually located at quite a distance from the paraproct region 
(“pa” of Fig. 73), although their location above the phallus is 
rather suggestive of that of the prongs “sh” of the roach (Figs. 
97 and 99). Pantel, 1915, very strongly opposes the idea that 
the vomer “v” (Fig. 51) of the Phasmids is homologous with 
