124 HISTORY OF BRITISH ZOOPHYTES. 



Hab. On shells, and roots of Fuci, and not unfrequently 

 with us on the branches of Halidrys. It is common at 

 Troon, and at other places on the Ayrshire coast. I have a 

 specimen from Newfoundland. 



It is loosely branched, cells smooth, not crowded, in some 

 specimens a little wrinkled across. It is white, and two o'r 

 three inches high. 



There are two varieties, the one upright, and the other 

 more branched and spreading. 



" When this coralline was put into sea-water, I observed, 

 through the microscope, a polype occupy the inside of the 

 whole, and each denticle or cell filled with a part of it, end- 

 ing in tufts of tentacula. A small piece of one of the little 

 sprigs was put into a watch-glass of sea-water, and notwith- 

 standing the separation of its body, in five minutes' time 

 the claws or tentacula were moving about in search of prey." 

 Ellis. 



'2. SERTULARIA RUGOSA, Snail Trefoil Coralline, Ellis. 

 (Plate IV. fig. 11.) 



Hab. Parasitical on Flustra, sponges, and seaweeds at 

 low -water mark; not uncommon. There is a variety which 

 is erect, and another variety which creeps along the frond 

 of Flustra foliacea. Seen by the naked eye, it has no beauty, 



