F. J. Meggitt 311 
There are the usual four longitudinal canals, two ventral and two dorsal, 
communicating by a circular commissure at the posterior end of each pro¬ 
glottis. The two dorsal are small, and the two ventral relatively large, the 
commissures connecting the latter being often one-third the dorso-ventral 
diameter of the proglottis. Besides these four vessels there is an extensive 
irregular meshwork of ill-defined vessels and lacunae. Of the additional 
longitudinal vessels described by investigators and stated to be characteristic 
of the genus I have been unable to find any trace. The network referred to 
above is of far too vague a character to correspond in any way with a definite 
system such as is to be found in the other species, e.g. 0. tetragonocephala 
(Bremser). 
The genital pore (PI. XVII, fig. 13) irregularly alternates and is situated 
near the anterior extremity of the proglottis. It leads into a well-developed 
genital cloaca into which the vagina and cirrus open in the usual manner. The 
genital ducts pass between the dorsal and ventral excretory vessels and dorsal 
to the nerve. The male organs are fully developed in proglottides slightly 
broader than long, the female in those longer than broad. The cirrus-sac (c.s.) 
opens into the genital cloaca dorsally to the vagina. Lying diagonally, it 
extends well past the ventral longitudinal vessel, in some cases half-way 
across the segment. The cirrus is unarmed, has a small terminal knob, and 
coils slightly in the cirrus-sac. The vas deferens inside the sac is also coiled. 
It leaves the cirrus-pouch at the inner extremity on the ventral side, and, 
coiling once or twice, proceeds half-way across the proglottis near the dorsal 
surface, immediately dorsal to the uterus but not passing between the lobes 
of the ovary. At the level of the anterior extremity of the vitelline gland it 
breaks up into a number of vasa efferentia. The testes (t.) are between 30-50 
in number and lie posteriorly and laterally to the female glands, not ex¬ 
tending anteriorly further than the ovary. They form one layer dorso- 
ventrally and do not extend laterally beyond the longitudinal excretory 
vessels. 
The vagina (v.) opens at the posterior limit of the genital cloaca and runs 
transversely to half-way between the two ventral longitudinal vessels. After 
coiling once or twice it opens into the oviduct in the centre of the proglottis. 
A receptaculum seminis is not present. The bilobed ovary (ov.) is situated 
in the anterior third of the proglottis, the basal portion being dorsal and the 
two lobes reaching the ventral side. Between these two lobes lie the greater 
part of the courses of the vagina, uterus, and oviduct. The latter springs 
from the ventral surface of the common basal portion of the ovary and pro¬ 
ceeds in a straight line posteriorly to meet the vagina. From this meeting 
place the oviduct curves first posteriorly, then anteriorly to the ventral 
surface of the proglottis, receiving at the posterior limit of its course the 
vitelline duct. On the ventral surface it runs anteriorly past the level of the 
vaginal pore, then bends at right angles to run across the segment to the 
dorsal surface where it opens into the uterus. The yolk-gland (y.g.) lies 
