MAMMALIAN CESTODES. tf 
followed out from beginning to end, the tube became connected 
at one blind extremity with the outer layer of the body by a 
scattered group of subcuticular cells. This as it appears to me 
may represent a previously existing pore. As I possess no 
younger example of the plerocercoid than the one described here, 
this point cannot be settled. Cavities having the character just 
described are few in number and are not always to be seen in 
a given series of sections. The letter B in text-fig. 2 points 
to a cavity of a completely different character from that which 
has just been described. This cavity is always single, and by 
following out its course there is seen to be only one of this 
nature in the whole body. Furthermore, it does not traverse the 
whole body but is restricted to the hinder end (as I have termed 
it), and does not nearly extend to the end which is occupied by 
the numerous cavities of the third character (cf. text-fig. 4) to be 
shortly described. The cavity is median in position and occupies 
about three-elevenths of the entire length of the worm’s body. It 
occupies the last third of the worm but does not by any means 
extend to the very end. This cavity is not marked off from the 
surrounding solid tissues by any definite wall. On the contrary, 
in certain places at least the appearance is as if the tissues had 
gradually become broken down at the edge to form this central 
cavity. It fact it seems to me to be fairly certain that this is the 
true bladder-cavity, which agrees in most particulars with the 
bladder-cavity of such a form as the Piestocystis from the snake 
Hoplocephalus superbus, described by Prof. J. P. Hill*, con- 
eerning which that author writes +} :—‘“ The bladder-cavity in this 
form is represented by an irregular cavity occupying the centre 
of what represents the caudal bladder of ordinary Cysticerci and 
not distinctly marked off from the surrounding ground-tissue. 
The cavity is filled by a granular material consisting of a homo- 
geneous matrix with granules which stain deeply with cochineal, 
and which represent the products of degeneration of the original 
central tissue.” Jam therefore disposed to compare and regard 
as equivalent these spaces in the two immature tapeworms, and 
to consider, as a consequence of this comparison, that the area in 
Urocystidiwm which is occupied by the space in question is the 
hinder end. There is, however, as I have already intimated, no 
confirmation of this view by the discovery of a scolex. The 
cavities lettered ““C” next require attention. These cavities 
vary greatly in size, but are never so large as the bladder-cavity 
already described. They are either absent or if present neces- 
sarily peripheral where the bladder-cavity is at its largest, and 
often come to lie close under the subcuticular layer of the body- 
wall of the worm. Hence the clear spherical cavities discernible 
in the living worm and duly referred to above. 
These cavities, however, contain no trace whatever of any. 
“* “ A Contribution to a further knowledge of the Cystic Cestodes.” Proc. Linn. ' 
Soc. N.S.W. (2) ix. p. 49. + Ibid. p. 52. 
