F. J. Meggitt 
407 
before. At tbe nearest point to which they approach each other, the 
two vessels of the same side communicate by a rather wide dorso- 
ventral connection (d.v.c.). At this portion of their course, the four 
vessels have the same diameter, 0-004 mm. Half-way along the anterior 
course of the two parallel vessels a dorsal and a ventral branch (.s., s.') 
are given off to the posterior margins of the dorsal and ventral suckers 
respectively. Having reached their inner limit, the four vessels run 
anteriorly again, just exterior to and touching the outer sheath of the 
rostellum. The two vessels of the same side again communicate by 
a small dorso-ventral vessel (d.'v.'c.'), at about the posterior two-thirds 
of the length of the sucker. A short distance anteriorly the two vessels 
of the same side bend round to meet and fuse with each other. At the 
same time each gives off an exceedingly slender branch ((.') which 
penetrates the outer sheath of the rostellum and runs near its inner 
surface as far as the posterior level of the hooks. Here the four vessels 
open into a circular commissure (c.c.) running mid-way between the 
outer sheath of the rostellum and its muscular axis. This is the only 
connection between the vessels of opposite sides, throughout the whole 
course of the strobila. Along their whole course the four rostellar 
vessels give off numerous fine branches, some of which appear to proceed 
to the suckers: but as the diameter of the main vessel itself is only 
0-002 mm., it is clearly impossible to follow the much smaller branches. 
Male Organs. The genital pore is unilateral, slightly anterior to 
the mid-point between the anterior and posterior margins of the pro¬ 
glottis, and in transverse sections can be seen to be a little ventral of the 
mid-line. The cirrus-pouch (PL XX, fig. 10, c.p .) is small and cylindrical, 
reaching just past the dorsal longitudinal excretory vessel. It is 
0-089 mm. long and 0-025 mm. wide: its inner end is 0-025 mm. from 
the margin of the proglottis. It opens into the dorsal side of the genital 
sinus, running from thence dorsally to the nervous and excretory vessels : 
its whole course is directed towards the dorsal surface. The cirrus-sac 
itself is straight, with the exception of its extreme outer end which has 
a slight ventral bend. The cirrus is short, straight, and unprovided 
with spines of any kind. At its inner end it opens into a large internal 
vesicula seminalis within the cirrus-sac, occupying the greater part of 
its length. The vas deferens running from this internal vesicula 
seminalis ( v.s .) is cylindrical and curved, with the concavity directed 
ventrally: it lies on the dorsal surface of the proglottis, reaching nearly 
to the middle line. The testes ( t .) (0-057 mm. dia.) are dorsal in position, 
one being situated in the pore half of the proglottis, the other two in 
