Zoology of Barents Sea. 273 



Genus Flustra, Linnseus. 



Flustra membranaceo-truncata, Sinitt. 



An essentially Arctic form. Id this species membranous 

 processes are given off from the back of the cells, terminating 

 in branched fibrils, by which the zoarium is attached. This 

 structure, which is not shared by other members of the genus, 

 points to some peculiarity in the conditions of life. 



Genus Membranipora, Blainville. 



Membranipora monostachys } Busk. 

 On stones &c, lat. 74° X., long. 24° E., 220 fms. 



Membranipora lineata, L. 

 On stones off Bear Island, 25 fms. 



Membranipora craticula, Alder. 



On stones off Bear Island, 25 fms. [St. Lawrence, Daw- 

 son.] 



Mcmbraniptora Sophia?, Busk. 



On stones off Bear Island, in 25 fms. 



Membranipora arctica, Smitt. 



Extremely common. This is the most abundant species 

 amongst the dredgings from Barents Sea. It occurs creeping 

 over stones, shells, &c, and also erect and free, forming ex- 

 pansions composed of a single lamina or of two {Hemescha ra 

 or Eschara auctt.). In the Hemescharine state the dorsal 

 surface of the zocecia is seen to be thickly covered with minute 

 white disks. Lat. 74° N., long. 23° E., 220 fms. ; and off 

 Bear Island, 25 fms. 



Genus Microporella, Hincks. 

 Microporella ciliata, Pallas. 



On stones off Bear Island. The zocecia are much calcified 

 and often coarsely grooved, the furrows extending from the 

 margin to the umbo, which overhangs the pore. The latter 

 is suborbicular and strongly dentate, and is placed in a hollow 

 between the umbo and the lower lip. The avicularium is 

 very generally wanting. 



