78 BICELLARIID^E. 



cending spiral; branches broadly flabellate, dichoto- 

 mously divided, arching outwards. Zocecia in two to 

 six series^ elongated, slightly raised towards the upper 

 end ; aperture reaching nearly to the bottom ; a single 

 spine at each upper angle. Aviculm'ia on the outer 

 cells moderately large, the head much swollen and 

 rounded behind, with a short beak abruptly bent at 

 the point, placed near the top of the cell ; avicularia on 

 the inner cells small. Ooecia subglobose, prominent, 

 the upper part opaque, with a hyaline border round the 

 orifice, which rises into a peak or into a blunt rounded 

 process in front. Height of the shoots from 1 to 2 

 inches. 

 Polypide with about 13 tentacles. 



Habitat. On rocks and stones near low-water mark, 

 and in shallow water. 



Localities. Herm, under stones; Guernsey; Menai 

 Straits (Alder) : Whitburn (Rev. G. C. Abbes) : Seaham 

 Harbour, co. Durham (G. Hodge) : Tenby (Dyster) : 

 Filey, Yorkshire; Llandudno, dredged off the Ormes 

 Head; Isle of Man; Ilfracombe, very common; South 

 Devon, very fine and abundant, near low-water mark ; 

 Swanage Bay, Dorset, on drift wood (T. H.) : Falmouth 

 (Cocks) ; Malahide (Trin. Coll. Collect., Dublin) . 



This fine species is nearly related to the preceding, 

 with which it had been confounded until detected by the 

 late Mr. Alder's keen and discriminating eye. 



It attains a much larger size than B. avicularia ; the 

 flabellate branches are broader ; and the whole habit is 

 stouter. It occasionally reaches a height of two inches, 

 and forms large clustered growths beneath the ledges of 

 rocks, in the clefts and gullies, and on the under surface 

 of stones near low-water mark. As many as a dozen of 

 its lovely spiral shoots will sometimes rise from the mass 



