CONTRIBUTIONS TO THE ANATOMY OF EARTHWORMS. 471 
thick and appear to be made up of fibres. Interspersed among 
them are nuclei which are extraordinarily numerous ; the blood 
supply was not very great, but this may be due to accidental 
causes. The presence of egg-sacs in Pericheta has been 
noted in but few species. Bergh (18, p. 318, footnote) 
remarks upon the presence of two pairs of egg-sacs in P. 
Hasselti; the first pair are situated in the ovarian segment 
above the ovary; the second pair in the following segment 
occupying a corresponding position. He also quotes Perrier’s 
(33, p. 116) observation of a pair of apparently similar structures 
lying above the ovaries in P. robusta. In P. aspergillum 
there are two pairs of egg-sacs lying in segments x11 and xiv; 
like Bergh, I could find no ova in these egg-sacs, nor any 
connection with the oviduct. As, however, in Pericheta 
intermedia there is a similar absence of connection with the 
oviducal funnel and yet the egg-sacs are full of ova, I cannot 
agree with Bergh in regarding the egg-sacs of P. Hasselti as 
functionless (as egg-sacs). 
Bergh states that the ova of Lumbricus, although sur- 
rounded while in the ovary by a follicular layer of flattened 
cells, leave the ovary in a completely naked condition. So 
far as I am aware this statement is borne out by other obser- 
vers, who have figured or described the ova in the egg-sacs as 
without a follicular layer. This appears also to be the case 
with Criodrilus (Collin, 16) and Microcheta (Benham, 11, 
pl. viii, fig. 10). 
In Pericheta intermedia the egg-sacs were filled 
with mature ova, all of which were surrounded with 
a perfectly distinct follicular epithelium composed 
of flattened nucleated cells. 
In addition to this follicular epithelium—between which 
and the ovum is a distinct vitelline membrane—many of the 
ova were also furnished with asmall number (four or 
five) of germinal cells attached to one pole (see fig. 12). 
This is an interesting resemblance to certain of the lower 
Oligocheta, in the majority of which the ova are detached 
from the ovary and fall into the egg-sacs in company with a 
