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 inner 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 Flustra 

 foliacea. The polypes and pith of the stalk are of a yellow 

 colour. The polypes were sluggish, had twelve short tentacula 

 not cihated, 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. 



Alcyonidium 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 in every 

 respect. Mr. Hassall (Annals of Natural History, vol. vii. p. 370) 

 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, innumerable bubbles of gas are seen rising from all parts of 

 its surface. On immersing another portion in aqua potassse 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. Figm-e 11 is a magnified view of a few of the cells in 

 the portion of the polypidom thus treated. Each 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 eminence by the eversion through it of 

 a second portion, surmounted by pretty long setae. The tenta- 



* As has already been stated, 1 liave observed individual polypes both in 

 Cellularia reptans and scruposa^ but 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, kyi, 2F 



