NATICA. 221 



quently in immature specimens) with also one or two similar 

 rows round the periphery of the last whorl: epidermis very 

 thm, 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 : spire short, slightly promi- 

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

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

 suture 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 ty/rather sharply 

 incurved above, and having a blunt edge: inner lip 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 projects 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 : umbilicus rather large and deep, for the most 

 part open, marked with several slight obliquelv spiral grooves : 

 operculum horncolour, microscopically and closely striated in 

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

 spects like that of JV. sordida. L. 1-4. B. 1-4. 



Yar. conico-ovalis. Spire somewhat elongated or drawn 

 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 t, and by Professor Dickie in 

 Lough Strangforcl, from 15 /to 25 t; 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 



