ALECTO. 279 



series, the upper portion of the cells erect, with a circular entire 

 aperture. Johnston. 



1. ALECTO GKANULATA, W. Thompson. 



Hab. On the inner surface of old bivalve shells, more 

 rarely on the outer surface. It is a deep-water species. It 

 is said to be not uncommon; but the only specimen we 

 have met with was on the outer surface of Pinna ingens, 

 from the island of Coll. 



It is slender, branched, adherent, the tubular cells lean- 

 ing a little to the opposite side. It is glossy, when fresh, 

 and dotted with minute granules. When in a dead state, 

 it is of a dull white colour. 



2. ALECTO MAJOR, D. L. (Plate XVI. fig. 60.) 



Hab. Island of CoU, D. L., from Rev. Mr. Nicol; island 

 of Sana, dredged by W. Thompson ; Cornwall, Mr. Couch. 



This was a species new to our Fauna when I discovered 

 it on a valve of Pinna ingens, from Coll. I sent it to Dr. 

 Johnston, and he mentions, in his description of it, that I 

 said that the young unbranched specimens resembled a tear 

 slowly trickling down the cheek, and swelling in its pro- 

 gress. Pull-grown specimens, however, are irregularly 

 branched, though each branch has the fulness we have 

 mentioned, at the termination. It is much stouter and 



