GASTEROPODOUS MOLLUSCA OF BERWICKSHIRE. 265 



3. T. tumidus, shell conical, obtuse, greyish-white mottled with 

 darker spots or lines, spirally striated ; whorls six, flattened on 

 the upper margins, the superior minute ; base convex ; umbilicus 

 small ; aperture roundish. Diam. f^ths ; height ^ths. Flem. 

 Brit. Anim. 322. Tr. patholatus, Dillw. Rec. Sh. 776. 



Hab. Berwick Bay, rare. 



4. T. Margarita, shell depressed, subglobular, flesh-red and clouded, 

 iridescent, smooth ; spire lateral, of four whorls, the apex obtuse ; 

 base rounded; umbilicus small; aperture round, perlaceous. Diam. 

 th. Gray, in Zool. Journ. ii. 567. Helix Margarita, Laskey, 

 in Wern. Mem. i. 408. tab. 8. fig. 5. Turbo Margarita, Lowe, 

 in Zool. Journ. ii. 107. tab. 5. fig. 10, 11. Flem. B. Anim. 299. 



Hob. On the fronds of sea-weed, not uncommon. 



This pretty shell is glossy, and in some lights reflects metallic colours : it is 

 smooth, or only marked with the striae of growth, but the base has some 

 faint impressed spiral stria?. Tentacula two, slender, white, setaceous, 

 with the eyes on a pedicle at their external base : foot ovate with plain 

 margins : sides furnished with tentacular filaments, four on each side : 

 margin of the cloak between the tentacula rounded and beautifully ore- 

 nulate. When the animal is in motion the shell is placed laterally. 



The snail is active and quick in its progression, moving by very evident un- 

 dulations of the foot. It adheres to smooth surfaces less tenaciously 

 than most snails do, and is easily shook from its hold ; nor does it seem 

 to be so readily alarmed. When in confinement, it rarely leaves the 

 water entirely ; and it swims in a reversed position, but seldom, and 

 with much less than its usual freedom. It lives naturally at low water- 

 mark, and is usually found among the roots or on the frond of Laminaria 

 digitata, or perhaps still oftener on the dulse (Khodomenia palmatu), 

 which is probably a favourite food. 



9. NATICA. ADANSON. 



Shell globose, smooth, the body-whorl very large, and the spire 

 small ; aperture lunated, the pillar-lip oblique, toothless, with a callus 

 more or less concealing the umbilicus ; outer lip acute, plain ; operculum 

 horny. Zoophagous. 



1. N. monilifera, shell subglobular, smooth, greyish tinged with 

 brown, and a row of brown waved stripes along the tops of the 

 whorls ; whorls six, the body very large, obscurely angled on the 

 shoulder ; spire somewhat produced, oblique ; umbilicus deep, open, 

 obscurely striate. Length l^ths; breadth 1 inch. Lam. Anim. 

 s. Vert, vi. ii. 200. N. glaucina, Flem. Br. Anim. 319. Nerita 

 glaucina, Pen. Brit. Zool. iv. 344. tab. 90. fig. 1. 



Hab. Ross sands. 



The waved oblong spots which run up the shell at the base of the sutures are 

 concealed or obscured in recent specimens by the thin glaucous epider- 

 moid covering. The umbilicus is not contracted by a deposition of callua, 

 and is spirally striated ; pillar white, thickened ; outer lip thin, even, 



