38 
fibrilles. The muscular nuclei occur solely in the interstices between 
the fibres. Thus the zone of nuclei outside the muscular envelope 
characteristic for the true vesicula seminalis is entirely absent. A 
similar development of the muscularis may be found in the large 
seminal canals, so that the muscular wall of the seminal vesicles 
is simply such a musculature developed on a 
large scale. On their medial side each seminal 
vesicle sends out a short and muscular efferent 
duet, which runs somewhat obliquely caudad 
toward the median line. Into this duet the 
seminal vesicle, noticeably contracted during 
preservation, empties its content of sperma 
(Plate, Fig. 3). The two efferent duets fuse 
underneath the prostate giand (Plate II, Fig. 4), 
at the border of its anterior third, into a ductus 
ejaculatorius, which runs in a straight line 
backwards to the penis. This is traversed 
almost in its entire length before fusion oceurs 
with the nearly parallel-running efferent duet 
from the prostate giand (text-fig. 13). The ductus 
ejaculatorius is covered with a low, thickly 
ciliated epithelium, and is surrounded by a 
muscular layer that is more than twice as thick as that of the 
efferent duet of the prostate vesicle. In both duets the longitudinal 
muscle fibres lie nearest the epithelium, and outside of these is 
the mueh stouter circular muscular layer. 
The prostate vesicle (Plate II, Fig. 4) has an elongated oval 
shape with a thick muscular envelope of sparse, thick fibres. 
Numerous efferent duets from the extra-capsular prostate giands 
traverse the muscular coat. Internally the vesicle is lined with a 
low, slightly ciliated epithelium, which contains distinet cells between 
which the efferent glandular ductules from the underlying stouter 
layer of giands open. The vesicle is not chambered, but has 
only a few small and more lateral irregular folds of its epithelium. 
Medial sections disclose the straight, even outline of the epithelium; 
thus distinetly different from the more differentiated prostate ve¬ 
sicle of the genus Stylochus. The prostate is situated just in front 
of the penis, half-way between the d^rsal and ventral sides, 
Text-fig. 12. Outline 
drawing of male 
genital apparatus 
set-n in ventral aspect. 
d e, ductus ejacula¬ 
torius ; f. V. s, false 
seminal vesicle; p, 
penis; ph. p, pharyn- 
geal pocket; pr, 
prostate vesicle. 
