158 littorinidte. 



backwards. The diameter, for the most part, is not even 

 a single line. 



The animal is of a hyaline white. Its head is pro- 

 longed into a rather broad muzzle. The tentacles are 

 rather long, cylindric, or subulate, wdiite, with conspicuous 

 black eyes or bulgings at their external bases. The foot is 

 short. Beneath the transparent operculum is seen the 

 slight process or rudimentary filament terminating the oper- 

 CLiligerous lobe. As it walks it usually drags its shell 

 sideways, so that often the hinder 2)art of the foot only is 

 applied to the ground. The tentacula, whilst the creature 

 is moving, are often turned back or directed laterally. 

 The operculum is thin, horny, and of very few turns. 



This little Mollusk lives in great numbers under stones 

 at low water, and among the stems and roots of Co- 

 raUina officinalis. It is found, usually in great abun- 

 dance, all round the shores of the British Islands, but from 

 the smallness of its size often escapes notice. It ranges 

 throughout the boreal and arctic seas. 



S. NiTiDissiMA, Adams. 



Extremely minute, polished, neither ribbed nor spirally 

 striated, pellucid : suture simple ; aperture not circular. 



Plate LXXIII. fig. 7, 8. 



Hclice nitidissima, Adams, Trans. Linn. Soc. vol. v. pi. 1, f. 22, 23, 24, from 



which Mont. Test. Brit. vol. ii. p. 447 ; Maton and Rack. 



Trans. Linn. Soc. vol. viii. p. 205; Turt. Conch. Diction. 



p. 58. 



Turbo nitidissimus, Fleming, Brit. Animals, p. 300 (from Adams). 



Truncatella 9 utoimis, Phil. Wiegm. Archiv. Nat. 1841, p. 54, pi. 5, f. 4 ; Moll. 



Sicil. vol. ii. p. 134, pi. 24, f. 5 (most probablj-). 

 Sinra nitidissima. Brown, Illust. Conch. G. B. p. 20, pi. 8, f. 42, 44 (from 

 Adams). 



