Physiology of some Zoophytes. 393 
the gullet and commencement of the intestine is smaller, and that 
part marked a in fig. 4 and 5 is relatively larger in this polype 
than in Cellularia reptans and C. scruposa, and has less the ap- 
pearance of an appendix of the stomach*. Its mner surface, how- 
ever, is covered with a greater number of brownish granules than 
any other portion of the intestinal tube. 
Campanularia dumosa. I have procured some live specimens 
of this polype thrown ashore after a storm attached to Mustra 
foliacea.. The polypes and pith of the stalk are of a yellow 
colour. The polypes were sluggish, had twelve short tentacula 
not ciliated, and presented all the characters of the Zoophyta hy- 
droida. Dr. Johnston writes me that he has also some time ago 
procured live specimens, so that he must be now aware that 
this polype cannot be a Cornularia as he once supposed (British 
Zoophytes, p. 192, 1838), and that the characters of the poly- 
pidom separate it from the genus Campanularia. 
Alecyonidium parasiticum. Abundance of this polype is occa- 
sionally thrown ashore chiefly adhering to Sertularia argentea. I 
have procured several specimens alive, and have satisfied myself 
that it consists of cells composed of animal and calcareous mat- 
ter, and that the polype resembles the ascidian polypes m every 
respect. Mr. Hassall (Annals of Natural History, vol. vii. p. 3870) 
first satisfactorily ascertained the true nature of this polype. On 
placing a portion of the polypidom under the microscope, and 
then bringing a quantity of dilute muriatic acid in contact with 
it, Imumerable bubbles of gas are seen rising from all parts of 
its surface. On immersing another portion in aqua potasse so 
as to destroy the animal matter, it lost its dirty brown colour, 
and the form and arrangement of the cells were then distinctly 
observed. Figure 11 is a magnified view of a few of the cells in 
the portion of the polypidom thus treated. Hach cell is pro- 
vided with a flexible tube attached to its margin, which the po- 
lype extrudes before it emerges from the interior of the cell, and 
retracts when it re-enters, thus serving the purpose of an oper- 
culum. The first portion of this operculum extruded, forms a 
small conical eminence with the apex truncated. When the po- 
lype withdraws itself within its cell, it frequently does not retract 
this portion of the operculum, so that the surface of the polypi- 
dom occasionally presents under the microscope a papillose ap- 
pearance. The next stage in the protrusion of the polype is the 
elongation of this conical emmence by the eversion through it of 
a second portion, surmounted by pretty long sete. The tenta- 
* As has already been stated, I have observed individual polypes both in 
Cellularia reptans and scruposa, bat more especially the latter, where the 
difference between the size of the stomach and appendix was less marked 
than in figs. 4 and 5. 
Ann. & Mag. N. Hist. Vol. xvi. 2F 
