76 BICELLARIIDiE. 



mously into narrow linear segments, disposed spirally 

 round the stem. Zocecia biserial, elongate, narrowed 

 below, elevated towards the oral end ; aperture occupying 

 more than three fourths of the front of the cell, ob- 

 ovate ; margin thin, with two spines above on the outer 

 side and one on the inner. Avicularia large, com- 

 pressed laterally, with a much elongated and slightly 

 bent beak, placed on the outer edge of the aperture 

 about halfway down the cell. Ocecia subglobular, 

 prominent, free, hyaline and smooth. 

 Polypide with 14 to 15 tentacles. 



Habitat. On shells, zoophytes, Flustra foliacea (espe- 

 cially), &c., between tide-marks, and from moderately 

 deep water (20-50 fathoms) . 



Localities. The Minch, Hebrides; Shetland, not com- 

 mon (A. M. N.) : Peterhead and Wick, on Flustra 

 foliacea, &c., from deep water (C. W. P.) : Coralline 

 ground on Flustra foliacea (Dr. M'Intosh) : Northum- 

 berland, from deep water, occasionally (Alder) : Hastings 

 (Mr. Tumanowicz) : South Devon, not common (T. H.) : 

 Cornwall, on the Corwich Crab, Megavissey Bay and 

 Mount^s Bay, not common (Couch) . 



Geographical Distribution. Spitzbergen, Sorje Bay, 

 40-50 fathoms (mud bottom), rare; most northern part of 

 Spitzbergen, on Cellularia and Flustra, 20-50 fathoms 

 (Smitt) : Adriatic (Heller) : Hobson^s Bay, Australia 

 (MacGillivray). 



This is a smaller and less striking species than the 

 following, and apparently less common. It is of slender 



aperture is also said to occupy half the length of the cell, whei'eas that 

 of B. avicularia extends to very near the bottom. Van Beneden himself 

 points out. differences between his species and tluit of Ellis, though he 

 seems to have been lialf inclined to identify them. 



