LIFE-HISTORY OF BUCEPHALUS HAIMEANUS. 669 
runs a vas deferens. These unite with one another to form 
« common duct, which enters the seminal vesicle on its dorsal 
side (fig. 56, sv.). 
The seminal vesicle opens into an ejaculatory duct whose 
walls in part are lined withan epithelium of coarsely granular 
cells. I can find no nuclei in this layer. This epithelium 
extends through about two-thirds of the length of the ejacu- 
latory duct, where it is succeeded by a thin membrane which 
continues to the genital sinus (fig. 56). 
The space between the wall of the penis sheath and the 
ejaculatory duct is filled with parenchyma cells (fig. 45). 
The character of this tissue changes in the portion of the 
penis which lies within the sinus, becoming here much reticu- 
lated and spongy in appearance (fig. 56). 
The genital sinus, lined by a cuticle which appears similar 
to that covering the body, opens to the exterior through a 
short duct which is surrounded by a layer of circular muscles. 
I have been able to make no observations as to the manner 
in which the male organ functions. The surface of that part 
lying within the sinus is much folded. It seems probable 
that this portion is a true penis, 1. e. is protrusible. 
Molin (11, 1861) gives a figures of G. armatum in which 
the penis is extended. 
Though self-fertilisation may be possible, the arrangement 
of the genital apertures and the structure of the genital 
atrium seems to render it improbable. Spermatozoa set free 
in the genital atrium might make their way into the uterus. 
Spermatozoa are to be found in all parts of the uterus, 
though nowhere in such great abundance as in the seminal 
receptacle, and in that part of the uterus just after the shell 
glands. They are also present in Laurer’s canal, through 
which, it is probable, they are simply making their way to 
the exterior. 
The eggs, seen in section in the oviduct, are irregular in 
outline, giving the impression of being ameceboid bodies. 
Fertilisation probably takes place before the egg passes into 
the ootype. 
