4A8 WwW. A. HASWELL. 
having the appearance of a rounded group of vesicles each en- 
closing a minute spherical mass of chromatin. Thisappearance 
it still retains after the sperm has entered the cytoplasm, the 
actual union of the male and female nuclei was not observed. 
The polar bodies (fig. 23, pl.) were embedded in the cytoplasm 
not far from the surface in all cases in which they were de- 
tected, and if they ever become actually separated out, the 
separation evidently takes places at a later stage. 
The material of the thin egg-shells in which the fertilised 
ova are enclosed is secreted by the ova themselves, and not 
derived from any special glands. In some eosinated prepara- 
tions this is rendered very obvious, some of the ova being 
surrounded by a discontinuous investment of droplets or gran- 
ules, others having a complete shell, while droplets or granules 
of what appears to be the same material are discernible in 
the substance of the ova, both fertilised and unfertilised, and 
in the spaces between them. 
The mode of passage of the fertilised eggs to the exterior 
remains doubtful. The spaces in which they lie have no 
definite outlet. Gardiner gives a diagram of the parts in 
Polycherus in which the “ vitelline glands ” enclosing the 
eges are represented as opening on the exterior by means of 
the female aperture. This is not in accord with Mark’s 
observations on that genus. In Heterocherus such a 
communication does not exist. I can merely conjecture that 
when a number of completed eggs have accumulated a tem- 
porary passage is formed between the space in which they 
lie, and the lumen of the antrum. A short, blind, anterior 
diverticulum of the latter, which occurs in some specimens, 
and is shown in fig. 17 (k) may be a vestige of such a tem- 
porary outlet." 
During the breeding season, when a number of specimens 
were kept for aday or two, many of them deposited their 
1 Gamble and Keeble (8) state that in Convoluta roscoffensis the 
eggs may be laid singly without disintegration of the parent, or a number are 
discharged at once with rupture of the parent, which sometimes breaks into 
two parts. 
