334 MURICID^E. 



smooth and polished: inner Up forming a glaze, the limit of 

 which is parallel with the outer lip, not spread on the lower 

 side ; it becomes thicker towards the base, and lines the inner 

 side of the canal : pillar slightly curved, and bevelled inwards : 

 opercidum(in a specimen from Iceland) pear-shaped, and rather 

 thick, with oblique layers of increase. L. 5*5. B. 2. 



HABITAT : South-eastern coast of Shetland, 40-50 

 miles from land, in 78 f. ; two specimens only were 

 procured, both dead, but one in an excellent state of 

 preservation. Mr. Walpole possesses a specimen from 

 the Wexford coast. Sars, Loven, and Danielssen have 

 taken this species, together with F. gracilis, on many 

 parts of the Norwegian coast, north of Christiansund, 

 in 40-100 f. ; M' Andrew and Barrett also dredged both 

 in Finmark, in 30-50 f. ; Iceland (Chemnitz, Mohr, 

 and Steenstrup) ; Faroe Isles (Morch) ; Greenland 

 (Fabricius, as Tritonium antiquum, Moller, and Pingel) . 



It is much larger than the next species (F. gracilis) , 

 which has been confounded with it by many authors ; 

 F. Islandicus is more spindle-shaped, being produced 

 and attenuated towards the base; the canal is much 

 longer, and in some specimens quite straight ; the whorls 

 are more rounded; the apex is stiliform and prominent; 

 and the ridges are less crowded, and are sharper or 

 more raised, especially on the upper whorls. The odon- 

 tophore differs nearly as much from that of F. gracilis 

 as the latter does from F.propinquus in the same respect. 

 The pleurae in F. Islandicus and F. gracilis are exactly 

 similar ; but the rhachis in the present species is broader, 

 and has three distinct and nearly equal points at the 

 base. In F. propinquus the pleurae have a more deeply 

 lobed fang in front; and the rhacliis is still broader 

 and straight behind, with cuspidations as in F. Is- 

 landicus. 



Dr. Jonas pointed out the distinction between F. Is- 



