282 HISTORY OF BRITISH ZOOPHYTES. 
Hab. Very common on seaweeds, such as Dasya coccinea 
and Delesseria sanguinea ; common also on other zoophytes. 
This ivory-tufted coralline, though generally as white as 
ivory, from which it takes its specific name, is occasionally 
tinted with rosy-red. It is much branched, nearly half an 
inch in height; cells in two rows, sometimes nearly alter- 
nate, at other times opposite. Pear-shaped vesicles are 
scattered over the branches, finely granulated. 
2. CRISIA DENTICULATA, Dr. Fleming. 
Hab. On seaweeds and corallines, like the preceding, but 
not nearly so common. It is not rare on the coast of Ayr- 
shire, but it is smaller in size than specimens from England 
and Ireland. The finest specimens I have are from Miss S. 
Beever, and from Mr. Tumanowicz, Hastings. They are 
above an inch in height, and as much in breadth. Its 
larger size and stouter texture, and still more its black 
joints, which give it a spotted appearance, enable even the 
naked eye to distinguish it from the preceding; with which, 
nevertheless, it was confounded, till Prof. J. Fleming 
pointed out the difference. 
3. Crista acuLtgata, 4. H. Hassall. 
Hab. Kingston Harbour, Mr. Hassall; near Larne, Mr. 
R. Paterson; Ballantrae, Ayrshire, Mr. W. Thompson. 
