fusus. 339 



species, and rather slowly increasing ; the last occupies a little 

 more than five-eighths of the shell : suture narrow, deeply 

 channelled : mouth oblong- oval, acute- angled above ; length 

 (including the canal) nine- sixteenths of the shell : canal rather 

 short and wide, turning to the left, half open, ending in a 

 large and obliquely curved . notch : outer lip rounded and 

 slightly flexuous, not projecting so much as in F. gracilis, but 

 more contracted or incurved above ; edge sharp and thin ; in- 

 side smooth and polished : inner lip forming a thin glaze : 

 pillar curved, bluntly angulated at the commencement of the 

 canal : operculum triangularly oblong, with an oblique con- 

 tour, thin, yellowish-brown or light horncolour, somewhat 

 concave and furrowed lengthwise at the distance of about one- 

 third from the outer lip, marked with fine and numerous but 

 irregular laminae of growth, and sometimes with a few slight 

 impressed lines down the middle, which radiate from the 

 nucleus. L. 1-75. B. 0*75. 



Var. turrita. Smaller and thinner, more slender and almost 

 cylindrical, with a longer spire. Tritonium turritum, Sars, 

 Arct. Moll. ]S T org. in Yet. Forh. Christ. (1858) p. 39. 



Habitat : Muddy and sandy ground in the coralline 

 and deep-water zones on the coasts of Yorkshire, Dur- 

 ham, and Northuniberland,Berwick Bay, Aberdeenshire, 

 Hebrides, and Shetland ; New Brighton, near Liverpool 

 (Collingwood) ; Dublin Bay (Kinahan) ; Cork (Hum- 

 phreys, fide Walpole) . The variety is from 78 f. off the 

 east of Shetland. Fossil in the Wexford raised beach 

 (Sir H. James) ; glacial beds, Aberdeenshire, at a height 

 of 150-200 feet (Jamieson). Finmark, 20-150 f. (Sars, 

 M f Andrew, and Barrett); Kullaberg, in South Sweden 

 (Lilljeborg); Cattegat (Jonas, as F. Listeri, var.). 



The shell of the female is more tumid than that of 

 the male. Capsules solitary, and attached to the in- 

 side of old bivalves ; they are hemispherical, and 

 resemble those of F. gracilis, but have a smaller 

 and oval orifice ; the base is margined by a narrow 

 membrane. Embryo the colour of a pomegranate. In 



q 2 



