228 naticidyE. 



winding into the interior of the spire, and separated from the 

 base of the shell by a deep furrow, which notches the pillar : 

 operculum horncolour, somewhat more solid than in other 

 British species, microscopically and very closely striated in the 

 line of growth ; spire concave, defined by an overlapping and 

 raised edge. L. 0-5. B. 0-475. 



Var. 1. albula. Whitish. 



Var. 2. conica. Spire more produced. 



Habitat : Not uncommon on a sandy or gravelly 

 bottom mixed with mud, and among nullipore, in 15- 

 90 f., throughout the Scotch, Irish, and north of England 

 coasts ; Isle of Man and Devon (Forbes) ; Plymouth 

 (Jordan) ; Cornwall (Peach, M' Andrew, and Hockin) ; 

 110-140 f. off the Mull of Galloway (Beechey, fide 

 Thompson) ; in the stomachs of gurnards at Cork 

 (Humphreys) . Both the varieties are Zetlandic. Clyde 

 beds (J. Smith) ; Aberdeenshire (Jamieson) ; post-gla- 

 cial deposits in Norway, 0-80 feet (Sars). Philippics 

 shell, of which he found a single specimen at Palermo, 

 and doubtfully referred by him to the Nerita helicina of 

 Brocchi, although it is not that species, may be ours, 

 and fossil also. Its foreign range is entirely northern, 

 from Iceland (Steenstrup and Torell) and Finmark 

 (Sars) to the south of Sweden (Loven and others); 

 depths 3-70 f. 



N. Montacuti sometimes swims in an inverted posi- 

 tion ; and it emits a thick slime from its foot. The jaws 

 are small and thin ; tongue thickly but not sharply 

 spinous, with an unarmed and curled point at the inner 

 extremity. This is the smallest of our native Naticce. 

 It is, besides, distinguishable from N. Alderi by its 

 colour, more globular shape, shorter spire, tumid whorls 

 (the last of which is not so disproportionately large, 

 viewed with the mouth downwards), wider and chan- 

 nelled suture, and by the umbilicus being rounder and 



