FARRELLA. 373 



1. BOWERBANKIA IMBRICATA, Adams. 



Hab. Parasitical on Fuci, and not uncommon. Exmouth, 

 rock-pools, and cast ashore in great masses, Rev. T. Hincks; 

 Frith of Forth, D. L. jun. ; Southampton and Portsmouth, 

 on the chains of the steam-ferries, Dr. Johnston. 



It is about an inch in height, in flaccid tufts. The 

 branches are smooth and transparent, in clusters on one 

 side, leaving the opposite side of the branch bare. When 

 the animal is expanded it has ten tentacula ; when alarmed 

 it contracts very rapidly, shutting itself up in a transparent 

 horny cell. The cells are connected by a cylindrical creep- 

 ing stem, on which they are thickly set. 



Genus XXVIII. FAERELLA, Ehrenberg. 



Gen. Char. Polypidom confervoid, creeping, fistular and mem- 

 branous ; the cells elliptical, scattered. Polypes ascidian, with 

 the tentacula forming a rather incomplete circle : no gizzard : 

 ova on exclusion without cilia. 



1. FAR.RELLA REPENS, A. Farre. 



Hab. Parasitic with a creeping stem on Sertularia, Dr. 

 Farre; in Strangford Lough, on seaweeds, W. Thompson. 

 " The cells have an oblong form, and are connected with 



