260 DR JOHNSTON'S DESCRIPTIVE CATALOGUE OF THE 



with a brownish margin; throat brown. Operculum horny, thin, ear- 

 shaped, turned spirally at the inferior and inner margin, whence fine 

 stri;r diverge to the circumference. 



The animal buries in sand at the very lowest recess of the tide, and is dis- 

 covered by the little hillocks which it raises above the shell. Dr Gould, 

 in his valuable and elaborate w Report on the Invertebrate Animals of 

 Massaclmsetts," p. 232, asserts that the Naticae are all very voracious, 

 and play a conspicuous part in devouring the dead fish and other animals 

 which are thrown up by the tide. The small circular holes with which 

 bivalve shells are often drilled are also, according to Dr Gould, the work 

 of these snails, and made by them to gain an entrance to the animal ap- 

 parently so well secured against such a foe. Their foot is very large, so 

 as -completely to envelope the objects on which they prey. 



2. N. Alderi, shell subglobular, smooth, flesh-coloured with a white 

 .zone at the sutures and base, the body with five rows of arrow- 

 shaped brown spots, one continued round the base of the lesser 

 whorls ; spire small, slightly produced ; umbilicus partly covered 



-by callus and brown. Length T 4 5 ths ; breadth about ^ths. Forbes, 

 Faun. Mon. 31. Nerita glaucina, var. B. Turt. Conch. Diet. 125. 

 Hogg, in Lin. Trans, xiv. 320. tab. 9. fig. 3-8. 



Hob. Berwick Bay, occasionally found in the refuse of fishing-boats. 



Operculum semilunate, horny, with a narrow membranous edge. The white 

 band on the shoulder of the body -whorl, under the suture, is occasionally 

 obscure or obsolete. A brown narrow fascia always enters within the 

 umbilicus, and the callus, on the pillar above it, is more or less tinted 

 with the same colour. 



3. N. helicoides, shell ovato- conical, smooth, white, immaculate, 

 coated with a yellowish epidermis ; whorls five, rounded, separated 

 by a channelled suture ; the spire produced, rather obtuse ; aper- 

 ture pure white with a small fissure on the pillar. Length i 6 5 ths ; 



breadth scarcely T %ths. Lyell in Phil. Mag. for May 1840, p. 

 365, fig. 12. 



Hab. Berwick Bay, very rare. 



This new species was found in the refuse of one of our fishing-boats. When 

 the epidermis is removed, the whorls appear to be very finely striolate 

 in a spiral direction. 



This shell, which departs from the normal form of the genus, Mr Lyell finds, 

 in a fossil state, in the " Norwich crag," when it appears to have been 

 much more abundant than in our present sea. Mr Lyell has given an 

 excellent figure of it, which will correct the faults of our own. In habit 

 <the species is closely allied to the Natica canaliculate of Gould. See his 

 Report, p. 235, fig. 161. 



I found, some time since, among the refuse of a fishing boat, a specimen of a 

 Natica which appears to be identical with the NATICA OLAUCINOIDES of 

 my friend Dr Thomas Thomson (Rec, Gen. Science, i, p. 133.), and which 

 Mr Alder tells me is certainly the NAT. CLAUSA described by Mr Smith 

 as a fossil found in the pliocene deposits of the British islands. I cannot, 

 however, affirm that the species still lives in our Bay, for the shell was 

 dead, and presented the same appearance as the subfossil specimens. 



10. TURRITELLA. LAMARCK. 



Shell turreted, tapered, with numerous whorls, the last not much 



