NATICA. 221 



quently in immature specimens) with also one or two similar 

 rows round the perij)hery of the last whorl : epidermis very 

 thin, buffcolour, to be seen only within the umbilicus, having 

 been rubbed off in other parts by the continual friction of the 

 sand which this species inhabits : sjnre short, slightly promi- 

 nent ; apex entire, flattened: luhorls 7, tumid and rapidly en- 

 larging ; the last occupies eleven-fourteenths of the spire : 

 .sw^Mr^ nearly straight, rather deep, and well defined: mouth 

 of the same relative dimensions as in the last species, slightly 

 expanding and angulated at the base : outer lip rather sharply 

 incurved above, and having a blunt edge: inner Up broad, 

 not very thick on the upper part of the pillar, forming a 

 slight ridge along that corner of the mouth, and a white solid 

 pad or callus in the middle, which ])rojects over that side of the 

 umbilicus ; the inner layer is more or less tinged with reddish - 

 brown, and sometimes also the inside rim of the upper part of 

 the body-whorl : umhiUcus rather large and deep, for the most 

 part open, marked with several slight obliquely spiral grooves : 

 operculum horncolour, microscopically and closely striated in 

 the line of growth, giving a fibrous appearance ; in other re- 

 spects Hke that of iY. sordida. L. 1-4. B. 1-4. 



Var. conico-ovalis. Spire somewhat elongated or di'awn 

 out. 



Habitat : Large sandy bays from Jersey (Dodd) to 

 Unst (J. G. J.), at low-water mark of spring tides and 

 down to about 10 f.; common. Shells inhabited by 

 hermit crabs (which had probably carried them into 

 deeper water) were dredged by Mr. Hyndman off the 

 Mull of Cantire in 40 f._, and by Professor Dickie in 

 Lough Strangford, from 15 to 25 f. j this shows the 

 advisability of recording in dredging-lists whether the 

 species so procured were living or dead. A specimen 

 of the variety was taken by me on Rossilly sands near 

 Swansea ; and M. Martin obtained the same variety on 

 the coast of Provence. This species is said to occur in 

 almost every upper tertiary fossiliferous bed in England^ 

 Scotland, and Ireland, including the deposit near Mac- 

 clesfield, 500-600 feet (Darbishire) , that on the Sussex 



