188 a 
may be seen by reference to text-figs. 3 and 4, in which the 
pericardial cavity is marked pcd. Text-fig. 4 has been intro- 
duced into the present communication because it shows well 
the manner in which the anterior blind horns of the collar 
cavities (c.c.) project forward, and the position which the pro- 
boscis canals (p.c.) occupy between the pericardium and the 
anterior horns of the collar cavities. The part marked 2.c. in 
this figure is not the true extremity of the notochord ; the tip 
of the notochord is bent dorsally as shown in text-fig. 3, and 
does not therefore come in the plane of the section represented 
in text-fig. 4. 
Gonads.—All the polypides of C. gilchristi that have been 
examined possess either two ovaries or two testes ; no herm- 
aphrodite individuals like those of C. migrescens and C. 
hodgsont, possessing one ovary and one testis, were met with. 
Ripe female polypides do not, as a rule, have two large 
ovaries ; there is usually a large ovary and a comparatively 
small one. In text-fig. 5, A and B represent the two ovaries 
of one polypide drawn to the same scale of enlargement, and 
C and D represent the two ovaries of another polypide. If the 
female is immature, the two ovaries are of the same size. As 
in other species of Cephalodiscus, the ripe ova of C. galchriste 
are large in comparison with the size of the ovary, and they are 
heavily charged with yolk. A ripe ovum is seen in text-fig. 5, 
C, and two in B. All ovaries, whether mature or not, have a 
short pigmented duct. The duct is shown uppermost in the 
figures A-D, and the pigmented cells are represented in these. 
figures by black dots. In the polypides preserved in formalin 
the pigment is bright red, in others it is brownish, or even dark 
brown. In some cases, as in C. hodgsoni (“‘ Discovery ” Re- 
ports, pl. 5, figs. 44, 45), the red pigment is not confined to the 
duct, but occurs throughout the ovary. 
The testes of the male have no red cells in their ducts. 
They vary in size according to the maturity of the individual, 
and the two testes of one polypide are usually equal in size. 
Examples of testes dissected out of four different polypides 
are shown in figures E-H of text-fig. 5. Figure G represents 
the largest testis found during the investigation. On teasing 
up some of the testes, and staining the contents, perfect sper- 
metazoamay be seen. They have long, sharply-pointed heads, 
and long tails (text-fig. 5, J). 
Free ova occur in the tubular spaces of the tubarium of 
specimen 10265 mixed up with the buds of the occupant 
polypides ; also in 13203 and 186551. They are surrounded 
by a thin film of transparent material resembling that of the 
test, and this in some cases 18 produced into a sort of stalk 
