522 BULLIDiE. 



level with the top of the last volution, and is square- 

 topped and narrow, being contracted posteriorly by the 

 swell of the body. The outer lip, which is acute and 

 simple, there being no actual fissure, though in the adult a 

 rather broad excised area (as in Akera) is produced near 

 the suture by the advance of the labial edge, juts out for a 

 very short distance at a right angle to the body, then sud- 

 denly advances and slants downwards, and finally arches 

 considerably, so as to round off" the lower end of the 

 aperture. An umbiHcal crevice is partially concealed by 

 the raised and slightly reflected edge of the pillar, which 

 latter is straightish, inclines a little to the left, and occupies 

 at most one half the length of the aperture. Our largest 

 example was two lines and a quarter long ; its breadth 

 was a line and a half.* 



The animal is white, and entirely retractile. Mr. Alder 

 remarks that it keeps its eyes under the protection of the 

 transparent shell, through which it looks as through a 

 window. 



Specimens are most frequently procured from shell sand. 

 Mr. Alder has found it alive in pools between tide marks 

 at Cullercoats. We have taken it alive from the roots of 

 Laminaria in Zetland, and dead in as deej) as thirty 

 fathoms (E. F.) ; Scarborough (Bean) ; Weymouth and 

 Devon, Bristol Channel (Jeffreys) ; Loch Fyne and He- 

 brides (Barlee) ; Portmarnock (Warren) ; Cork (Hum- 

 phreys) ; Donegal (Mrs. Hancock). 



It ranges northwards to- the shores of Norway, and is 

 probably distributed through the Arctic and Boreal seas. 



* We can scarcely perceive an appreciable difference between this species and 

 the Bulla dclilis of Gould (Invert. Massacli. p. 164, f. 95), which last is declared 

 by MiJllcr to be his B. sitljangulata (Index Moll. Groenl. p. 6.) 



