238 GEO. H. BISHOP 
ribbed surface of the vesicle, and the tails project into the lumen. 
When spermiogenesis is complete and all the sperms have become 
attached, a cross-section of the organ (fig. 5b) shows, inside 
the muscular ring, first a ring of nuclei following the contour 
of the inner surfaces of the spiral ridges, then a distinct line of 
sperm heads at the surface of the epithelium, and finally the 
remainder of the lumen almost filled with the sperm filaments 
radially arranged, extending outward from a narrow central 
space. ‘The spermatozoa even after attachment show a grouping 
into bundles. 
Region of the ejaculatory duct. The development of the 
ejaculatory duct and its junction with the mucous gland-vas 
deferens fundament has been referred to above. The relation 
of the three parts, mucous gland (7), proximal part of vas deferens 
leading from the seminal vesicle (h), and the ejaculatory duct 
(j), requires a more detailed description (text fig. 1 and pls. 1 
and 3). 
The paired mucous glands lie parallel in the posteroventral 
region of the abdomen; the bulbous ends containing the mucous 
accumulation point anteriorly. The basal portion of each gland, 
with which both vas deferens and ejaculatory duct connect, 
bends at an angle of about 45° in the medioventral direction 
(text fig. 1). The tips of the two glands meet medially. The 
ejaculatory duct divides as it enters the Junction of the two 
glands, and a branch penetrates the wall of each. 
The vas deferens (h) makes a sharp curve from the seminal 
vesicle and enters the gland on the medial side, dorsal to the 
entrance of the ejaculatory duct (j). Around and particularly 
above the entrance of the vas deferens, the muscular wall of the 
gland is greatly thickened, and projects into the gland’s cavity 
as a lip or valve guarding the entrance of the vas deferens ((). 
This valve partially cuts off from the body of the gland anterior 
to it the basal portion of the gland’s cavity (7) into which lead 
both ejaculatory duct and vas deferens. It thus divides the 
cavity of the gland into two regions at the bend of the gland 
described above. One region of the gland’s lumen becomes 
distally an elongated sac containing mucus, lying parallel to the 
