286 JOURNAL OF CONCHOLOGY, VOL. 9, NO. 9, JANUARY, I9OO. 



Dornoch Frith. This stands in the same relation to the type as var. 

 quadrifasciata does to Lacuna divaricata ; it is more dependent on 

 the shape than on the prominence of the tooth or sculpture, the latter 

 characters being as variable as in the type. It is widely diffused, but 

 scarce. Forbes and Hanley figure this as O. striolata, but not well ; 

 the sculpture is too prominent and the base not sufficiently keeled ; 

 but Sowerby's is just the thing. 



Var. nana Jeffr. (J. Conch., vol. 7, p. 253, 1893). — Scilly 40 f. 

 (Burkill and J. T. M.); Torbay; Cumbrae; Skye ; W. Orkneys 45 f. 



O. plicata Mont. — Scilly Islands ; Margate ; Freshwater West ; 

 Aberdovey ; Isle of Man ; Bantry Bay ; Mayo and Sligo ; Bundoran. 



Var. carinata Marsh. (/. Conch., vol. 7, p. 253, 1893). — St. 

 Aubin's Bay, Jersey. 



This is not a variable species, and no mistake ought to be made 

 about it. It is long, narrow, and tapering, with compressed whorls 

 and shallow sutural lines. The thickened rim round the top of each 

 whorl is rather more pronounced than in the allied forms. The only 

 difficulty of determination is with the immature forms, which may 

 lead astray, and the very young are almost indistinguishable from the 

 same stage of O. turrita. It is not perceptibly thinner than that 

 species, the tooth is always visible, and it may be known from any of 

 the slender forms of O. turrita by the last whorl being proportionally 

 longer and larger. Specimens with the whorls somewhat rounded, 

 a correspondingly deeper suture, and a shorter spire, from Margate, 

 Torbay, and the West of Ireland, are much like O. albella var. sub- 

 cylindrica ; but they have a more pointed apex, a stronger tooth, and 

 a proportionally smaller body-whorl and mouth. Another form from 

 the West of Ireland is also more convex, and conical in shape. The 

 largest come from Jersey, attaining a line and a half, and it is most 

 abundant at Fowey and Torbay. A monstrosity with turreted whorls 

 comes from several parts of the South Devon coast. 



Jeffreys' figure is not slender enough, and should not be umbilicate; 

 Forbes and Hanley's is too much so, but otherwise very good ; and 

 Sowerby's is totally unlike ; it has the spire too long and slender, the 

 tooth too prominent, and the mouth too wide and projecting. There 

 is no excuse for these incorrect figures, as it is a comparatively uni- 

 form shell. 



O. insculpta Mont. — Living in sea-weeds at low spring tides in 

 Torbay, and down to 90 fathoms, on nearly all our coasts. 



Var. laevissima G. O. Sars (J. Conch., vol. 7, p. 253, 1893).— 

 Guernsey 20 f. ; Scilly 40 f. ; Torbay i2f. ; Knapdale Lochs 10 f. ; 

 Clyde 18 f. ; Ionai6f. ; Gairloch 30 f. ; the Minch 50-70 f. Also 



