FISSURELLA. 471 



teeth are so arranged that many of them appear bifid. 

 Few examples exceed an inch in length. 



Animal bulky, varying in colour from tawny and creamy 

 white, through various shades of yellow to a rich orange 

 approaching scarlet, in the latter case only in such speci- 

 mens as are taken from the surface of scallops incrusted with 

 crimson sponge. The head is placed beneath the shorter end 

 of the shell ; it is tumid with a rather prominent muzzle, 

 and bears two stout subulate tentacles, but capable of consi- 

 derable elongation ; at their external bases are very short 

 pedicles bearing rather small eyes. The mantle is very 

 wide-margined, extending beyond the edges of the shell ; 

 above the head it is produced so as to form an expanded 

 hood or veil ; its edges are scalloped, and bear on their 

 upper surface, immediately under the margin of the shell, 

 a circle of very small and short but stout cirrhi, correspond- 

 ing to the ribs. The foot is very large, expanded, ovate, 

 and broad-sided. At its junction with the body there is 

 a row of short cirrhi, more than thirty in number in a 

 specimen of average size, and usually alternately larger and 

 smaller ; the cirrhus next the head is rather longer than 

 the others. Above the line of cirrhi the sides are paler 

 coloured than below. The anal tube is of a brownish 

 white colour and has simple margins. 



This Mollusk is western and southern in its range, 

 extending from the English Channel, round by the Irish 

 Sea and west coast of Ireland, to the Hebrides, and 

 thence to the Orkneys. We are not aware of its having 

 been taken in the German Ocean northwards of the Kentish 

 coast. It is found usually adhering to shells, and ranges 

 from the laminarian zone to as deep as fifty fathoms. The 

 following localities will illustrate its range : Herm (S. H.) ; 

 Margate (S. H.), in fifteen to twenty fathoms ; west bay 



