LACUNA. 67 



widest behind, the anterior end capable of being extended 

 considerably beyond the head, the margins plain, but there 

 are two very short filaments between the hinder part and 

 the operculum. It swims on the surface in a reversed 

 position, and it frequently leaves the water to settle on the 

 surface of fuci exposed to the atmosphere." 



This species in one form or other, is universally distri- 

 buted around the British Islands, living on Laminarise 

 just below low-water mark, and often cast up dead upon 

 sandy shores. It ranges all round the boreal regions of 

 the North Atlantic. 



L. cRAssioR, Montagu. 

 Ovate-conoid, strong, never banded ; pillar not canaliculated. 



Plate LXXII. fig. 5, 6. 



Turbo crassior, Mont. Test. Brit. vol. ii. p. 309 ; Suppl. p. 127, pi. 20, f. 1. — 

 Maton and Rack. Trans. Linn. Soc. vol. viii. p. 159. — 

 TuRT. Conch. Diction, p. 198. — Fleming, Brit. Animals, 

 p. 299. — Brit. Marine Conch, p. 1G7. — Dillw. Recent Shells, 

 vol. ii. p. 820.— Wood, Index Testaceolog. pi. 30, f. 12. 

 „ palUdus, DoNov. Brit. Shells, vol. v. pi. 178, f. 4. 

 Lacuna crassior, Turt. Zoolog. Journ. vol. iii. p. 192 — Johnston, Berwick. 

 Club, vol. i. p. 271. — Ha.nl. Brit. Marine Conch, p. xx.xix. 

 —Brown, lllust. Conch. G. B. p. 10, pi. 10, f. 43. 



This anomalous Lacuna is strong, nearly opaque, has 

 an ovate conoid shape, is covered with a rather thick dull 

 yellowish epidermis, that is disposed in obliquely longitu- 

 dinal flakes, beneath which the shell is almost smooth, a 

 little glossy, and of a cream or pale pinkish hue. The five 

 volutions, whose longitudinal increase is rather quick, termi- 

 nate in a small depressed and not particularly pointed apex ; 

 their line of division is simple, but the whoids (except the 

 apical ones which are simply rounded) appear peculiarly 



