POLYZOA OF THE E.M.B.C. DISTRICT. Ot 
its nature; and there is a third and smaller one under 
the head. 
The portion between the basal cylinder and the medial 
swelling is about the same length in all the specimens I 
- have examined, but the part between the medial swelling 
and the head varies very greatly. In one colony there 
was, along with the ordinary type, a form without a 
medial swelling, but the length of the stem was equal to 
the first joint in the others. This may be an imperfectly 
developed specimen, and it would seem to indicate that, as 
the individual grows, the head swelling becomes the medial 
one by an elongation of the upper joint. The differences 
in length of the upper joint also favour this view. 
The stem may be described as a rigid chitinous tube. 
Now chitin, being merely a product of the ectodermal 
cells, cannot be regarded as supplying any living con- 
nexion between the different parts of the zoarium. But 
under a high power a very delicate tissue of elongated 
nucleated cells is seen, inside the chitinous covering, 
connecting the different muscular parts in the stem and 
stolon.* 
The specimens were collected by Professor Herdman, 
off Port Erin, in the summer of 1885, and were adherent 
to seaweeds (Ptilota, &c.). It has not since been observed 
in the L.M.B.C. district. 
Besides the above additions to our fauna, the following 
observations have been made on species previously recorded. 
Alcyonidium gelatinosum, Linn. 
Some points in the anatomy? of this species have been 
worked out; and it has been found to contain certain 
* Busk has observed the same ‘‘parenchymatous tissue” in other species 
of Ascopodaria, 
+ Lomas, ‘‘Proc. L’pool Biol. Soc.,” vol. i., p. 29. 
