SCrvUPOCELLAEIA SCABRA. 49 



culum entire, suboval ; a portion of the surface slightly 

 hollowed out, forming a depressed area, with a lobate 

 margin. Lateral avicularia moderately large, with a 

 slightly hooked beak ; a pedunculate avicularium on 

 the lower part of each cell, below the aperture. 



Vibracular cells wedge-shaped, stretching transversely 

 across the back of the zooecium ; vibracula short, 

 not exceeding the cell in length. Ooecia somewhat 

 flattened in front, subglobose, with a smooth subtrian- 

 gular space above the aperture, from which fine lines 

 radiate towards the margin. 



Radical fibres long and slender, and scattered over the 

 whole of the zoarium. 



Height about ^ to | inch. 



Habitat. On stones, &c., from shallow to deep water. 



Localities. Northumberland coast, from the deep- 

 water boats (Alder) : Durham coast (Brady and Hodge) : 

 off the Firth of Forth, one specimen (C. W. P.) . 



Geographical Distribution. North Sea (Van Ben.) : 

 Scandinavian and Arctic seas (Smitt) : Spitzbergen, 6 

 fms., and more frequently 80-150 fms. (Swedish Exped.): 

 Davis Straits, off Frcderickshaab, 100 fms. (Wallich) : 

 Greenland, Godhavn Harbour, Disco, 5-20 fms. {' Valorous ' 

 dredg.) : Reykjavik Harbour, 15-20 fms. (Wallich) : 

 Madeira (J. Y. Johnson). 



S. scabra bears a strong general resemblance to S. 

 scrupea, but differs from it in several important particu- 

 lars. The operculum presents commonly a three-sided 

 figure, narrowing off towards the peduncle. It is de- 

 pressed in the centre, and is not unlike a saddle in shape. 

 It is further distinguished by the hand-like pattern sculp- 

 tured on its surface. The lateral avicularium is smaller 

 than that of the allied species, and wants its strongly 

 marked beak. On the other hand, the pedunculate avicu- 

 laria are of larger size, and much more constantly present. 



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