280 HISTORY OF BRITISH ZOOPHYTES. 
more conspicuous than the preceding species, and can 
scarcely escape observation. It adheres, also, more firmly 
to the shell on which it grows, the basis spreading beyond 
the cells, and the cells are unmarked with granules. 
3. ALECTO DILATANS, WV. Thompson. 
Hab. Island of Sana, dredged by Mr. Hyndman; coast 
of Northumberland, Prof. W. King; dredged off the Mull 
of Galloway, in from 110 to 140 fathoms, by Professor KE. 
Forbes; island of Islay, Lady Emma Campbell. 
This is a pretty species, as may be seen in Dr. Johnston’s 
plate xlx. fig. 5, 6. It creeps along on the surface of 
bivalve shells in a branching manner, each branch being 
fullest at the top, as in the preceding species. The cells are 
tubular, and a good deal immersed; they are also marked 
with granules. Dr. Johnston says that he has sometimes 
thought that it might be a state of Diastopora obelia. We 
have seen it in circumstances which thoroughly convinced 
us that it was quite distinct from D. odelia. Some time 
ago my friend the Rev. Mr. Nicol, of Coll, sent me some 
valves of Pinna ingens, dredged from deep water by the 
fishermen of that island. I valued the Prana, but I prized 
much more the zoophytes that were parasitical upon it. 
There were various fine Leprahe, some of them in the 
