396 Tapeworms of Birds 
seminis and on its pore side a large duct arises and leads into the oviduct. 
The oviduct runs dorso-ventrally near the centre of the proglottis, 
leading ventrally to an ovary (ov.) similar to that described byBlanchard, 
and having its cavity divided by septa into numerous incomplete 
compartments. Dorsally it passes to the shell-gland, receiving there 
the duct from a ventral, roughly quadrilateral, vitelline gland (v.g.). 
From the shell-gland it runs anteriorly to the extremity of the recep- 
taculum seminis, there to pass dorso-ventrally across the proglottis and 
open on the ventral side into a small uterus. It passes the receptaculum 
on its pore side. The uterus is a small simple sac on the ventral surface 
of the proglottis, between the anterior border and the ovary. From 
the latter it is only separated by a few strands of parenchymal tissue 
which break down upon sectionising, thus causing the two spaces to 
seem in communication with each other. Only by careful examination 
of the ducts can it be distinguished from the many cavities of the ovary. 
It is not persistent, being present only in two proglottides. By about 
the sixth segment its walls disintegrate and the eggs become scattered 
throughout the parenchyma. These in the following proglottis are 
enclosed singly in large spherical cavities (PI. XIX, fig. 4) the walls of 
which, as Blanchard pointed out in D. proglottina , correspond to the outer 
egg-membrane. The egg is of the usual Cestode type, with a diameter 
of 0-033 mm.; the diameter of the onchosphere is 0-023 mm. 
Conclusion. As can be seen from the above account, the form 
described presents many differences from allied species. Of the avian 
species of Davainea only eight have armed suckers and alternating 
genital pores: these are D. circumcincta (12), D. circumvallata ( 12 ), 
D. crassula (3), D. echinobothrida (io), D. hertwigi (9), D. insignis ( 12 ), 
D. proglottina (l), and D. urogalli (ii). Of these I). circumcincta and 
D. insignis are too inadequately described to enable them to be dis¬ 
tinguished. The remainder, with the exception of D. proglottina, can 
be separated from the form now under discussion by the position of 
the genital pore being half-way along the lateral margin instead of at 
the extreme anterior corner, this being a character not liable to variation. 
D. proglottina is therefore the species most closely allied to the new form. 
There are considerable differences between the two; these are given in 
Table I. 
In addition the female organs of the new form persist in segments 
five, six and seven, while these segments are not present in D. pro¬ 
glottina. It is obvious therefore that the two forms constitute two 
different species. A variety of I), proglottina, D. proglottina var. (labia- 
