6 POLYZOA. 



covered with vibratile cilia, by whose action it is 

 rapidly rowed to a resting-place. Here it adheres, 

 and quickly develops a cell, with its indwelling 

 animal, whence others grow in the order of ar- 

 rangement proper to its kind. 



Localities, &c. Some few of the encrusting kinds, 

 as Tubulipora patina, and the Membraniporce, and 

 some of the fleshy kinds, as Sarcochiton, &c., 

 spread on the surface of living sea-weeds. The 

 more ordinary support for the former is some old 

 shell or loose stone in deep water ; but not a few 

 select indifferently these or the surface of the solid 

 rock. The branched sorts, whether creeping or 

 erect, are found on the stems of growing sea-weeds, 

 within tide-marks and in deep water, as well as on 

 inorganic substances. The tiny whitish shrubs of 

 many species are among the most interesting as 

 well as the most familiar objects with which the 

 searcher for marine animals is conversant. 



Identification. The principal points to be ob- 

 served are the following: The form of the ten- 

 tacle-bell; the presence of a lip to the cell; the 

 connexion of the cells, whether by joints or ad- 

 hesion ; the arrangement of the cells, in one or more 

 rows ; the texture of the cells ; the presence and 

 number of birds -heads or whips ; the form of the 

 egg-cells and their position ; the shape of the cell ; 

 the shape of its aperture ; the presence of spines. 



Authorities. Mr. Busk's admirable " Catalogue 

 of Marine Polyzoa in the British Museum," super- 

 sedes every other so far as it has yet been pub- 

 lished, viz., to the end of the CHEILOSTOMATA. 

 For the rest, I am indebted to the second part of 

 the " History of British Zoophytes," by the late 

 Dr. Johnston, and to my own observations. 



