418 GILMAN A. DREW 
VDO, vas deferens opening into the mucilaginous gland. The opening is pro- 
vided with a sphincter muscle and the spermatozoa are allowed to enter only 
at definite intervals. 
X, a duct of unknown function. A ciliated, not glandular, duct which opens 
into the distal extremity of the middle tunic gland. It has been suggested 
that this represents the vestige of the right vas deferens, but this seems 
rather doubtful. 
Y, a glandular duct of unknown function that joins the finishing gland near the 
opening to the spermatophorie duct. 
PLATE 1 
EXPLANATION OF FIGURES 
1 Spermatophore completely formed as taken from the spermatophorie sac. 
The cap thread is shown broken at a little less than one-half the normal length. 
At this magnification the outer tunic is represented by a single line and ejacula- 
tory apparatus details are not shown. X 20 diameters. 
2 Oral end of a spermatophore. X 70 diameters. 
3 Oral end of a spermatophore. Represented as cut when fresh so the ejac- 
ulatory apparatus has expanded, uncoiled and thrust back through the cut ends 
of the outer and middle tunics. In this condition the free oral ends of the outer 
membrane, OM, and the inner tunic /7’, are more easily seen. X 70 diameters. 
4 Oral end of a spermatophore. Shown with the cap thread loosenipg. X 
70 diameters. 
5 Oral end of a spermatophore, after the cap has opened and the ejacula- 
tory apparatus had begun to evaginate. X 70 diameters. 
6 Oral end of a spermatophore, after the oral unornamented portion of the 
ejaculatory apparatus has evaginated and before the portion bearing the spiral 
filament has begun to evaginate. There is a slight pause at this stage of ejac- 
ulation. X 70 diameters. 
7 Oral end of a spermatophore , when the portion of the ejaculatory appara- 
tus bearing the spiral filament is evaginating. The spiral filament is broken 
into small fragments in the act of evagination. The fragments, which remain 
sticking to the inner membrane (now on the outside), are responsible for the 
broad, indefinite, spiral ornamentation on the outside of the evaginated tube. 
X 70 diameters. 
'8 A portion of the evaginating ejaculatory apparatus at a slightly later in- 
terval than shown in figure 7. This shows the relation of the membranes in the 
evaginating position. > 70 diameters. 
