LUNATIA. 341 



the inner margin, very slightly modifying the nmbilicus, where it 

 has a fissure at the posterior margin of the umbilicus ; a dense mass 

 of callus, within the aperture, at its upper angle, strengthens the 

 lip ; throat colored with dark chestnut, or transmitting the exterior 

 markings ; umbilicus rather small and simple, not much wrinkled 

 within ; operculum horny. Length, seven tenths of an inch ; breadth, 

 half an inch. 



Found along the whole coast to the north of Cape Cod, on fiats 

 which are left liy the tide at low water ; but it is as yet doubtful 

 whether it passes to the south of this limit. 



This has been thought by some to be the young of the preceding 

 species. In general aspect there is a resemblance ; but the propor- 

 tionate length of this is greater ; the thick, white callus indicates a 

 mature shell, and the dark portion of the upper whorls is at the 

 upper instead of at the lower portion of the whorl, as in iV. hews, 

 and the umbilicus is proportionally smaller instead of larger, as is 

 the case in young shells. Besides, I have never seen a large shell 

 in the localities where this species is abundant. The largest speci- 

 men I have seen, which I could distinctly refer to this species, is 

 less than an inch in length. It is evidently analogous to N. can- 

 rena of Europe. 



It varies in marking greatly. Some specimens are of a pale yel- 

 low color, and destitute of marking ; on some, the spots blend so as 

 to present alternate bands of light and dark color ; again, some of 

 the series are blended, and some are not. Tlie spots may be square, 

 oblong, or crescentic, and are usually oblique. The ivory-white cal- 

 lus seems to be the most constant character. 



Whole of New England coast, rare south of Cape Cod ( Simp- 

 son) ; Banks ( Willis) ; Magdalen Bay {Bell) ; Vineyard Sound, 

 six to twelve fathoms. 



Lunatia Grcenlandica. 



Fig. 166. 



Shell small, sub-oval, ash colored ; umbilicus imperfect ; operculum horny. 



Naticn pusilla, not of Say. — Gould, Inv. 1st ed. 237, fiir. 166. 



Natica Grcenlandica, Moller, Fauna Grcpnl. 7 — Stimpson, Shells of New England, 43, 



Lunatia Grcenlandica, Stimpson, Check Lists, 5, 



Shell sub-oval, liluish-white, with a light ash colored epidermis ; 

 surface glossy, smooth, or with merely microscopic revolving lines, 



