MARSHALl. : APDrriONS lO " BRITISH CONCHOI.OGV. I9I 



Some of the specimens from St. Bride's Bay are intermediate 

 between this species and the next ; they have the characteristic um- 

 bilicus of N. soj'dtda, but are greyish, thin, and globular, with convex 

 whorls, like -A'! catena. I have great doubts about Mr. Clark's 

 Exmouth record for this species. 



N. catena DaCos. — The ground colour of this shell is cinereous 

 or dove-colour, passing into buff of various shades. Those from the 

 Channel Islands are cinereous, while those from the west of Ireland 

 are a bright buff, very large and solid. 



Var. leckenbyi Marsh. ^ — Aberdeenshire (Simpson) ! Doggerbank, 

 10 f. This can easily be mistaken for the globular form of N. sordida, 

 previously mentioned, but the umbilicus is very different. 



Var. conico-ovalis Jefifr. — Herm Island and Torbay. 



N. g^laucina L. — Ground colour variable, white, pink, fawn, or 

 buff of various shades. The name — glaucina—xs not very apposite. 



Var. lactea Jeffr.- — Scilly (Smart and others): Aberdeenshire (Simp- 

 son) ! Guernsey and Herm ; Milford Haven. 



Var. subovalis Jeffr. — Aberdeenshire (Simpson) ! Herm Island, 

 Scilly, Milford Haven, and Bantry Bay. Not always fawn-coloured. 

 This and the previous variety are well figured in " British MoUusca " 

 as unnamed varieties of N. nitida. This one resembles N. ?nadlenta 

 Phil., but the umbilicus is different. 



Var. ventricosa Jeffr. — Birterbuy Bay (Walpole). 



This species has a wide variation in shape, size, markings, and length 

 of spire. Dredged specimens are much smaller than those living 

 between tide-marks. A large form from Torbay has a produced spire 

 and rounded whorls, resembling a half-grown N'. catena var. conico- 

 ovalis; and a monstrosity from Guernsey is compressed and elongated. 

 It is abundant near low-water mark at Herm, and on a hot day, on 

 the return of the tide, they spring out of the sand faster than they can 

 be picked up ; on one occasion I gathered quite a pint in this way. 

 The authors of " British Mollusca" record " a fine example, ten lines 

 in length by two less in breadth," but this must be erroneous, and it 

 was more probably an example of N". catena var. conico-ovalis. 



N. montacuti Forb. — lo to 140 fathoms. Off Fermain Bay, 

 Guernsey, 18 f , a single specimen in 1874 ; Scilly Islands, rare. 



Var. albula Jeffr. — Doggerbank, 40 f. : the Minch, 30 f ; ^Vest 

 Orkneys and East Shetlands. 



Var. conica Jeffr. — Doggerbank, 40 f ; the Minch, 30 f. ; Aber- 

 deenshire, West Orkneys, and East Shetlands. 



The last two varieties are sometimes combined in one form. Two 

 unnamed varieties from the Shetlands correspond to the vars. subovalis 

 and ventricosa of N. glaucina. I have a monstrosity from Lamlash 



I Ann. and Mag. N'at. Hist., ser. 4, vol. 16, p. 392, 1875. 



