336 MURICID.E. 



species : ivTiorJs 9, less convex than in F. Island'icus, but 

 like^yise compressed upwards ; the last is much broader towards 

 the base, and occupies more than two-thirds of the shell: 

 suture narrowish, and slightly channelled : mouth oblong-oval, 

 narrower than in the last species, and acute-angled above ; 

 length (including the canal) rather more than half the shell : 

 canal very much shorter than in F. Islandicu!^. turning some- 

 what abruptly to the left, wide, and two-thirds open, ending 

 in a large and obliquely curved notch : outer lip rounded and 

 slightly llexuous, not projecting so much as in the last species, 

 nor contracted or incurved above ; edge sharp ; inside smooth 

 and polished : inner lip forming a glaze, the limit of which is 

 coextensive with the outer lip : pillar curved, and bevelled 

 inwards ; it is sharply angulated at the commencement of the 

 canal': operculum triangularly oblong, rather solid, yellowish- 

 brown or horncolour, marked with fine and close-set hues of 

 growth, and lengthwise with a few slight and irregular striae 

 or impressed lines, which radiate from the nucleus. L. 3. 

 B. 1-25. 



Var. convoluta. Smaller, narrower, and somewhat cylin- 

 drical, more solid, with a longer spire, having sharper ridges 

 and a deeper suture ; mouth proportionally smaller. 



Habitat : Coralline and deep-sea zones, on all onr 

 coasts_, from 20 to 145 f . ; common on the northern 

 fishing-banks, but rare in the south of England. The 

 late Lord Vernon procured a specimen in the Scilly 

 Isles, and Dr. Lukis one at Guernsey. The variety 

 occasionally occurs in rather shallower water. F. gracilis 

 has been found in quaternary deposits at Kelsey Hill 

 (Prestwich), Macclesfield and Moel Tryfaen (Darbi- 

 shire) , and Wexford (James) . I do not consider the Crag 

 specimens wdiich have been referred to this species by 

 Searles AVood, Woodward, and Nyst identical with the 

 above. These last agree T\ith the North-American 

 form, which is smaller, more tumid, and has a short spire. 

 If such should prove to be distinct, it might be called 

 curtus. The present species appears to inhabit Behring^s 

 Straits (Wossnessenski, fide Middendorff) , White Sea 



