498 Wisconsin Academy of Sciences, Arts, and Letters. 
The vas deferens passes backward as a narrow tube nearly 
through the third segment, when it widens considerably and re¬ 
mains so as far as the middle of the fourth segment. This en¬ 
larged part, the seminal vesicle (PL XXXVI, Pig. 19), becomes 
very much twisted and often forms for its entire length an irreg¬ 
ular spiral. The duct leaving the seminal vesicle is: thicker than 
when it enters it, and in a, short distance unties in the median 
line, with the duct from the other testis. The short single tube 
thus formed, the ductus ej aculatorius, enters the base of the 
penis. ! i' ' : t| 
Each testis shows the two ends somewhat different, the an¬ 
terior is the more pointed and often ends in a short thread-like 
terminal filament; the posterior end is much blunter and in 
some specimens it had the appearance of being spirally coiled, 
but only once as markedly so as represented in (PL XXXVI,Fig. 
18). The projection from the ventral surface of the testis which 
we have: mentioned, is a little nearer the posterior than the ante¬ 
rior end; it is mlade up of six parts, the bases: of the seminal folli¬ 
cles, which disappear in the body of the testis, and at their proxi¬ 
mal ends unite to form the vas deferens. The testis is composed of 
the six follicles enclosed in a common scrotal membrane. When 
separated from one another, each follicle consists of this thick¬ 
ened, projecting, basal piece and an elongated thinner tube, 
which in sections, is seen to contain the different stages of the 
developing spermatozoa. The relative: lengths of these two parts 
we were unable, from our alcoholic specimens, to determine, but 
from the figures given by both Dufour (2) and Locy (5), the 
thick basal portion is but a very small part of the entire follicle. 
A section through the testis shows these follicles to be packed 
closely together. 
In the seminal vesicle we found that the wall changed very 
little but that the lumen became much enlarged and was, in all 
specimens examined, filled with spermatozoa. The tube might 
coil somewhat regularly for its entire distance or loop back and 
forth on itself from one end to the other, the most common oc¬ 
currence being, however, a mixture of the two 1 , with the coils 
predominating. Sections showed the wall to consist of a single 
row of epithelial cells (PL XXXVI, P'ig. 20 A) with a thin 
layer of connective tissue at their base. The nuclei were fairly 
large and spherical. 
The vas deferens emerging from the posterior end of the 
