FROM THE MERGTJI ARCHIPELAGO. 127 



a smooth and thickened border forms round the marginal region, 

 which is occupied by the vibracular cells. This crust gradually 

 extends until it covers a large proportion of the disk, patches 

 only of the strongly granulated surface appearing here and 

 there. 



Suborder Ctenostomata. 



Family BtrsKiiDiE, Hincks. 

 Btjskia, Alder. 



Buskia setigera, n. sp. (Plate XII. figs. 9-13.) 



Stem creeping, slender, jointed at intervals ; short, opposite 

 branches given off at the joints, usually bearing zooecia, the main 

 lines of the stem anastomosing (?). Zooecia perfectly transparent 

 and smooth, enlarged and rounded below, narrowing towards the 

 upper extremity (somewhat flask-shaped), attached to the stem 

 by a small basal process, the portion of the cell immediately above 

 the lower extremity decumbent and adherent, the rest suberect ; 

 the ventral side occupied by a large aperture, closed in by a mem- 

 branous wall, which extends from near the bottom to the top of 

 the cell; orifice terminal ; four slender setae of considerable length, 

 each springing from an expanded base, placed on the margin of 

 the oral extremity of the cell* ; one or two short tubular adhe- 

 rent fibres given off from the side of the basal portion of the 

 zocecium. Polypide small, and of very simple structure ; the ten- 

 tacular sheath with its pencil of setse, when fully extended, of 

 great length ; the setse, before expanding, loosely twisted sub- 

 spirally. 



Hob. On the stems of Nellia oculata, Busk, over which it 

 creeps in profusion. 



The occurrence of a second species of Buskia has a positive 

 interest, as throwing further light on a peculiar type of structure. 

 Hitherto the genus has been represented by Buskia nitens, Alder, 

 a smaller form than the present, which is not uncommon on the 

 English coasts and ranges from the Mediterranean to the extreme 

 north (Davis Strait, Barents Sea, White Sea) and to the Queen 

 Charlotte Islands in the North Pacific. B. setigera is compara- 



* In one or two of the figures (e. g. Plate XII. figs. 9 & 10) the spines are re- 

 presented as taking their origin at some distance below the top of the chitinous 

 portion of the zooeciuin ; they are really situated on the margin. 



