416 BULLIDiE. 



or slaty tinge in worn specimens : mouth narrow and of 

 equal width in the upper and middle portions, pear-shaped 

 and very wide at the base, which is rounded although some- 

 what truncated : outer Up nearly straight in the middle, with 

 a curved slope at each end ; the outer corner at the top is 

 bluntly rectangular, and not prominent; inner corner ob- 

 liquely incurved : apex twisted and slightly contracted, ob- 

 liquely truncated, encircled by a solid white rim or keel, and 

 concave in the centre ; perforation small and indistinct : mner 

 lip conspicuous, sometimes thickened, and partly folded over 

 the apex : pillar short, curved or somewhat twisted, and 

 having a broad fold at the base ; it abruptly turns to the left. 

 L. 0-6. B. 0-2. 



Var. linearis. Shell somewhat shorter, nearly smooth and 

 decidedly glossy, marked at each end with yellowish-brown 

 spiral lines, which are few and remote at the top, and close- 

 set at the bottom ; apex invariably perforated and exhibiting 

 part of the internal spire. 



Monstr. Base irregularly cup-shaped, with the edge re- 

 flected. 



Habitat : Muddy sand in the coralline zone, on all 

 our coasts, from Guernsey to Unst; rather common. 

 I obtained the variety in Loch Fyne and Shetland ; it 

 may be specifically distinct. The monstrosity is from 

 Tenby. This species occurs in the Clyde beds (Smith) ; 

 Red and Coralline Crag (Wood) ; Antwerp crag (Nyst) ; 

 French tertiaries (Grateloup and Mayer) ; Nice (Risso) ; 

 Italian tertiaries (Brocchi and others) ; Vienna basin 

 (Homes) ; Rhodes (Hedenborg, fide Homes). Its 

 ditfusion, as recent, extends from Vadso in East Fin- 

 mark (Danielssen) to Madeira and the Canaries (M^An- 

 drew), and throughout the Mediterranean (Risso and 

 others), Adriatic (Brocchi and Cantraine), and iEgean 

 (Forbes) ; depths recorded 3-160 f. 



Its habits are sluggish ; and its progress is painfully 

 slow, although by means of its foot it can crawl up the 

 side of a glass vessel. When irritated it emits a saiOPron- 

 coloured liquid. The head and the front of the foot, 



