48 LITTORINIDiE. 



The hreadtli of a full-sized individual of the former 

 variety was three quarters of an inch, and its length only 

 half; an example of the latter variety measured seven and 

 a half lines hroad, and seven lines long. 



The animal is usually of a bright yellow colour, but 

 occasionally, as in a variety we have taken in the Isle of 

 Man, is tinged with dusky, and has the tentacula and 

 muzzle nearly jet black. The former organs are slen- 

 derer than in its congeners, and the eyes placed rather 

 farther back. The mantle in the former variety is edged 

 with orange, in the latter with a black line. The opercu- 

 lum is tinged with rich brown. 



This species is abundant all round the British and Irish 

 coasts, living on Fuel, between tide-mark, but more espe- 

 cially inhabiting the third subregion of the Littoral zone, 

 tliat o^ Fucus serratus, where it is found in company with 

 TrocJius cinerarius. It ranges along the shores of the 

 Northern and Celtic provinces on the European side of the 

 Atlantic. 



species : — " Shell strong, subconic, smooth ; spire very short, being about one- 

 fourth of the length of the body, consisting of four well-rounded volutions ending 

 in an obtuse apex ; body large, tumid, crossed by some obscure lines of growth, 

 its upper margin provided with a narrow spiral groove, which continues throughout 

 the volutions; aperture subrotund, dark purplish brown within, pale fawn colour 

 within ttie margin of the inner lip, which is thin, and not continuous; pillar lip 

 glossy, white or pale reddish purple, broadly reflected on the columella, with a 

 very slight subumbilicus behind. Length nearly five-eighths ; breadth upwards 

 of three-eighths. 



" We discovered this species adhering to rocks below high-water mark, neiir 

 Downpatrick, Ireland, where it is very plentiful." 



