230 INTRODUCTION. 
at its base it is enveloped by a sbort prepuce. The vas 
deferens follows the course of the penis nearly to its 
summit. The genital bladder is oval ; its duct as long 
as the oviduct. 
In B. virgulatus the penis is long, irregularly cylin- 
droid, and has its base enclosed in a short prepuce. The 
vas deferens terminates in, and the retractor muscle is 
inserted into, its summit. The genital bladder is oval ; 
its duct is not more than one-third the length of the ovi- 
duct, and dilates as it passes downwards. 
In B. decollatus the penis is short, conico-cylindroid, 
and simple. The vas deferens enters near its base ; the 
retractor muscle is inserted into its summit. The ireni- 
o 
tal bladder is small ; its duct is narrow, and not longer 
than the neck of the oviduct. 
Pupa. In P. incana the penis is short, narrow, and 
cylindrical. The vas deferens is of a very great length 
when compared with what it is usually in the other 
genera. Its lower part, about the length of the penis, 
is dilated to the size of the latter organ, is strongly mus- 
cular, and terminates at the base of the penis. The 
retractor muscle is inserted into the summit of the latter. 
The lining membrane of the penis presents a single, longi- 
tudinal fold. At the base of the penis is a short, muscu- 
lar sac, or protuberance, probably a dart sac, although 
the individual dissected possessed no such instrument. 
The genital bladder is oval ; its duct is as long as the 
oviduct, and midway receives a long, narrow duct, de- 
