RISSOA. 1 1 9 



quick ; they are mostly short, but the penult volution 

 is scarcely more than twice as broad as it is long. The 

 width of the body is equal to its length, which last vies, 

 at the least, with that of the spire ; the basal slope is 

 rather abrupt, and decidedly rounded. The mouth, which 

 occupies three-sevenths of the total length, is obliquely, 

 and generally broadly, pear-shaped, being much contracted 

 above, and well rounded belovt' ; the peristome is con- 

 tinuous ; the throat is smooth. The outer lip is simple, 

 acute, moderately projecting, convex above, and much ar- 

 cuated below ; it is not patulous. There is no distinct 

 umbilicus, but a linear hollow exists beyond the slightly 

 elevated edge of the rather broadly reflected pillar-lip, 

 which last is white, shelving, subarcuated, and almost 

 perpendicular. Specimens rarely measure more than the 

 tenth of an inch in length, and rather more than half 

 as much in breadth. 



The animal of this species has not been observed. 

 This species, though its range extends all round the 

 British islands, appears to become much scarcer north- 

 wards, and is possibly absent from the Zetland shores. 

 It is chiefly an inhabitant of the Laminarian zone, whence 

 it is cast up among shell-sand, but ranges into the com- 

 mencement of the region of Corallines. We cite a few 

 of its localities ; Herm, dead on the strand ; Torquay, 

 along with parva (S. H.) ; Dartmouth in seven fathoms, 

 Milford Haven in twelve fathoms water (M'Andrew and 

 E. F.) ; many localities on the south and north-west coast 

 of England, also at Oban and elsewhere on the west coast 

 of Scotland (Jeffreys) ; Scarborough (Bean) ; Northum- 

 berland (Alder) ; Berwick (Johnston) ; Firth of Forth 

 in seven fathoms (E. F.) ; Aberdeenshire (Macgillivray). 

 In shell-sand from Magilligan, Bundoran, and elsewhere, 



