PLEUROTOMA. 391 



diminishing in the same ratio upwards; the whole surface 

 (except the apex, which is quite smooth and glossy) is covered 

 with extremely fine and close-set minute spiral striae, which 

 become stronger towards the base ; these spiral striae are par- 

 tially decussated by irregular microscopic lines of growth : 

 colour chestnut or reddish-brown, the ribs being (probably from 

 attrition) of a paler hue or sometimes whitish ; throat or in- 

 side of the outer lip purplish : spire extending to an abrupt 

 point : whorls 8-9, moderately convex, but compressed towards 

 the base and strongly angulated by the ribs ; the last whorl 

 occupies nearly three-fifths of the shell ; the first two or three 

 are cylindrical, and the topmost whorl is button-shaped : suture 

 slight : mouth irregularly oblong, acute-angled above ; length 

 about two-fifths of the shell : canal short, nearly straight, 

 extremely wide and open, truncated at the point, and ending 

 in a curved notch : outer lip flexuous, with a sharp arid even 

 edge ; it seems to form a wedge-like margin to the labial 

 rib : labial notch very broad, but shallow, placed at some 

 distance from the upper corner of the mouth : inner lip forming 

 a porcellanous glaze, and occasionally thickened above so as 

 to produce a pad or callus at the junction of the two lips : 

 pillar curved in the middle, and nearly straight below : oper- 

 culum as in the last species, sometimes folding inwards or con- 

 cave down the middle. L. 0-55. B. 0-2. 



HABITAT : Laminarian and coralline zones, in. 7-25 f., 

 on our southern and western coasts (including the 

 Bristol Channel), from Guernsey (J. Gr. J.) to Anglesea 

 (M f Andrew), all Ireland, and the west of Scotland; 

 Firth of Forth (Forbes, MS.), ?Dunbar (Laskey). 

 ? Fossil in Ireland (Forbes); south of Italy and Palermo 

 (Philippi and Calcara) . The only northern locality that 

 I can find recorded is Bergen, on the excellent authority 

 of Professor Sars : the distribution south of Britain is 

 very extensive, and comprises the coasts of France, 

 Spain, and Portugal, the Mediterranean, Adriatic, and 

 ^Egean ; Madeira and the Canary Isles (M f Andrew, as 

 P. secalinum). Bathymetrical range 6-40 f. 



My finest specimens were collected in Langland 



