1925] External Anatomy of Head and Abdomen of the Roach 213 
portion to the ninth sternite eha of Fig. 21 is overlapped by the 
eighth sternite and only the portion labelled sex projects as in 
Fig. 24. 
Usually the parts of the male genital apparatus are withdrawn, 
and are concealed by the hypandrium or ninth sternite. At the 
time of mating, however, they are protruded, and may remain so 
to some extent even when the male has been killed, as is shown in 
Figs. 21 and 24 — and in some cases the parts are even more pro- 
truded than is indicated in the figures in question. When the 
genitalia are boiled in caustic potash and spread apart, they are 
seen to consist of the following parts, shown in Figs. 23 and 25. 
The penis pe (Fig. 25) is membranous- walled and is possibly turgid 
in mating. It is located on the dorsal surface of the penislobus 
pel of Figs. 25, 24 and 23. The ejaculatory duct ej of Fig. 25, or 
common duct from the testes, utriculi, etc. of the male, conducts 
the genital products to the exterior through the meatus or open- 
ing on the side of the penis pe (Fig. 25). The walls of theejacul- 
tory duct are strenghtened by depositions of chitin, and muscles 
involved in the mating process, are attached to these structures. 
The glandopore, or opening of the conglobate gland, is indicated 
by the label o, just behind the asperate lobe asl, in Fig. 25. 
The pseudopenis psp of Figs. 21, 23, 24, and 25, serves to in- 
troduce the genital products of the male into the parts of the 
female at the time of mating, and on this account the structure 
in question has been called the penis by some investigators, but 
it is not homologue of the true penis (through which the ejacula- 
tory duct empties) of other insects, and on this account it is 
here designated as the pseudopenis. It bears a lateral papilla la- 
belled e in Figs. 25 and 21, and it is possible that a gland may 
open through this protuberance, although I was unable to find 
any trace of such a gland in the specimens treated with caustic 
potash. The process has been called the titillator by Brunner 
von Wattenwyl, and it has been suggested that it serves to dilate 
the parts of the female during copula, as may also the bird‘s- 
head-shaped, serrate lobe ser with its process fa (Figs. 25 and 23), 
although the latter may serve to anchor the parts when the male 
products are introduced during coitus. The opposing lobes op 
are called claspers by Walker, but nothing definite is known con- 
