A PARASITE OF THE TIGER SHARK. 
553 
the folds of the germ gland (see fig. 4L). The vagina passes close to 
the shell gland (figs. 36 and 37) and continues in its course a short dis- 
tance beyond that organ. Posterior to the shell gland it unites with 
the duct from the germ gland, and the common duct turns anteriorly to 
enter the posterior part of the shell gland. At the shell gland the 
common duct receives the duct from the vitelline gland. The vagina, 
thus reinforced, enters the shell gland at its posterior side and emerges 
from its anterior side as the oviduct. The latter proceeds forward for 
a short distance, then crosses from the dorsal to the ventral side of the 
segment, passing the vagina in its course and soon debouching into the 
uterus. 
The uterus is a conspicuous oblong organ, lying along the median 
line on the ventral side of the segment, and extending nearly to the 
anterior end of the segment. Its course and structure are shown in 
figs. 26, 27, 29, 30, 31, 40, and 41. The vitelline glands develop from the 
subcutaneous granulo -fibrous layer and consist of granulo-nuclear 
bodies, smaller than the lobes of the testis and lying mainly between 
the aquiferous vessels and the margins of the segment. The vitelline 
duct, which enters the duct leading to the shell gland, is made by the 
junction of two principal branches, one from each of the vitelline glands. 
The relative positions of the various female sexual organs are shown 
in the diagrammatic sketch, fig. 41 $ some details of structure are shown 
in figs. 36, 37, 38, 42, and 43. 
Along the ventral furrow the epidermis and cuticle are discontinu- 
ous and the uterus here lies near the surface. The furrow is probably a 
line of dehiscence through which, in ripe proglottides, the ova are dis- 
charged. Only the following observations have been made on the ova: 
Those which appear in the series of sections of a ripe proglottis pre- 
pared for this paper are small, about .014 mra in diameter, and without 
other shell than a thin, much shrunken membrane. Furthermore they 
seem to be held together in a common mesh of fibers which appear to 
be continuous with the membranous covering of the ova. In some of 
the sections of mature, not ripe, segments, the uterus contains numerous 
small, rounded, and fusiform masses of deeply stained granulo-nuclear 
materials, having the same general characters as the ova in the ripe 
proglottis (fig. 27). 
The elongated unidentified proglottides mentioned above (p. 544) 
contain large ova which are long, oval, and have a definite resistant 
shell. They therefore evidently do not belong to this species. 
