220 NATICIDJE. 



In Shetland also it occasionally takes or sucks the 

 fish-baits. Its horny jaws are large; and when ex- 

 panded they form a triangular plate. The size of my 

 largest specimen is I-f$ x -f^ inch. This species differs 

 from N. Grcsnlandica in size, solidity, colour, and the 

 umbilicus. 



It is perhaps the Nerita laevida of Laskey (Mem. 

 Wern. Soc. i. p. 409), who says, " It bears some resem- 

 blance to N. glaucina [N. catena], but has a more pro- 

 duced apex, and is divested of the markings of that 

 shell. " It appears to be the N. glaucina ? of Scacchi. 

 Swainson's N. sordida is N. plumbea of Lamarck, an 

 exotic species, to which Philippi erroneously referred 

 the European shell. 



j>l.*}fr- 4. N. CATE'NA*,(J)a Costal 



Cochlea catena, Da Costa, Br. Conch, p. 83, t. v. f. 7. N. monilifera, 

 F. & H. iii. p. 326, pi. c. f. 1, and (animal) pi. PP. f. 6 (by mistake 



as N. canrena}. 



BODY yellowish or drab, with a purplish tinge on the upper 

 part, and faintly lineated with purplish-brown : snout fleshy : 

 mouth or orifice of the proboscis globular, small, lying under- 

 neath the snout: tentacles rather long, slender, and pointed, 

 placed in the middle above the snout, and nearly concealed by 

 the front lobe of the mantle : [eyes " so excessively minute as 

 scarcely to be visible" (Clark) :] foot very voluminous, and when 

 at rest enveloping the greater part of the shell, divided across 

 so as to form two unequal portions, the posterior of which is 

 the larger, bluntly pointed behind ; front lobe notched or in- 

 dented in the middle : male organ situate under the right ten- 

 tacle : ovary pale yellow : liver dull olive. 



SHELL globose, and somewhat resembling an Ampullaria in 

 shape, moderately thick and solid, opaque, glossy : sculpture, 

 microscopical and very close-set flexuous spiral striae: colour 

 pale yellowish -white or buff, ornamented with a row of red- 

 dish-brown or light chocolate short, oblique, or zigzag, longi- 

 tudinal streaks at the top of each whorl, and sometimes (fre- 



* From its chain-like rows of spots. 



