NOTES ON OLIGOCHATES. 61 
20—25) arrange themselves round the walls of the sperma- 
theca, with their long heads deeply sunk in or between the 
lining cells, and their tails hanging into the cavity. Many 
bundles of spermatozoa also lie loose in the cavity, and may 
get carried into the alimentary canal (Michaelsen, 9). 
On the Celomic Corpuscles of Pachydrilus, sp. (?). 
It is not without hesitation that I put on record the following 
very incomplete observations on a small species of Pachydrilus, 
of which I unfortunately only found two specimens amongst 
the Enchytreids sent to me by Mr. Damon from Weymouth. 
On examining the worm under the microscope, the coelom 
was seen to contain a number of remarkably long and slender 
cells, attached to the body wall by one extremity (fig. 16). The 
longest of these cells reached nearly across a segment, being 
abont ten times as long as an ordinary celomic corpuscle 
(cp., a., and c., fig. 17). Near the middle was an oval clear 
region, indicating the position of the nucleus (n., fig. 17), whilst 
the body of the cell is formed of granular protoplasm, in which 
the granules could be observed circulating. No thick or 
definite wall was apparent covering the somewhat irregular 
surface, and the whole cell appeared to be very flexible, being 
twisted about backwards and forwards with the motion of the 
coelomic fluid. An expanded sucker-like foot or base ( ft.) 
served to fix it to the body-wall. In stained sections the 
nucleus appears small and rounded as in the ordinary oval 
corpuscles. 
Although it may seem extremely probable that these strangely 
shaped cells were parasitic Protozoa, yet the fact that there 
were present cells representing in appearance every stage 
between the elongated form and the ordinary ceelomic corpuscle 
(fig. 16) suggests that the former are derived from the latter. 
