NATICA. 339 



Bergen in Norway. It does not appear to occur south of 

 the Celtic region. 



N. HELicoiDEs, Johnston. 



White, longitudinally oval ; whorls narrowly scalar above ; 

 suture more or less distinctly canaliculated : axis imperforated. 



Plate C. fig. 6. 



Littorina « Lvell, Pliilos. Trans. 1835, pt. 1, p. 37, pi. 2, f. 10 (fossil). 

 Natka Helicoides, Johnston, Report Berwick. Club, 1835, vol. i. pp. 69, 266, 

 with figure. — Lyell, London and Edinb. Phil. Mag. 1840, 



pt. l,p. 365, f. 12 (fossil) Macgill. Moll. Aberd.p. 127. 



— Brit. Marine Conch, p. 149. — Brown, Illust. Conch. 

 G. B, p. 130, pi. 13, f. 24, 25. — Searles Wood, Crag 

 Moll. p. 145, pi. 16, f. 3 (fossil). — MiDDEND. Malacoz. 

 Ross. pt. 2, p. 88, pi. 7, f. 8, 9 (a varietj-). 

 „ canaliculata, Gould, Silliman's Journal, vol. xxxviii. p. 197; Invert. 

 Massach. p. 235, f. 161. — Philippi, Neue Conch, vol. ii. 

 p. 43, Nat. pi. 2, f. 12. 

 „ cornea, Philippi, Neue Conch, vol. ii. p. 43, Nat. pi. 2, f. 7 (as of 

 MOller, Moll. Groenl. p. 7). 



The shell is thin, a little transparent, quite smooth, and 

 of an uniform dull white hue, that is concealed externally 

 by a fugacious epidermis, which, in fine specimens, is of a 

 somewhat olivaceous yellow, but is horn-coloured in those 

 smaller examples that are more usually taken in our islands ; 

 it is of a longitudinally suboval shape, that is nearly 

 equally attenuated at both extremities. The whorls are 

 scalariform, and the narrow flattened ledge has an inward 

 inclination, so that the suture is more or less canaliculated. 

 The body, which is ventricose above, is manifestly atte- 

 nuated and somewhat produced below, where its basal de- 

 clination is very gradual and less rounded than in the ma- 

 jority of this genus. The spire, in the adult, is nearly equal 

 in length to half the body ; the longitudinal increase of its 

 turns, which are moderately ventricose, and taper but little 



