6 LITTORINID.E. 



ous on the upper than under part of the shell ; lahial rib thick, 

 sometimes double, or else having a varix on the body-whorl ; 

 top whorls quite smooth and polished : colour that of alabaster, 

 with a scarcely perceptible tinge of yellow and occasionally an 

 ochreous stain : spire moderately produced and pointed : ivhorls 

 5-6, convex, the last composing rather more than two-thirds 

 of the shell : suture distinct, but not deep or channelled ; the 

 separation of the whorls is chiefly indicated by the prominent 

 spiral ridge which surmounts each : mouth large, occupying 

 about half the length of the spire, roundish-oval, angulated 

 somewhat acutely above and obtusely below, and slightly ex- 

 panded outwards ; inside plain : outer lip semicircular, forming 

 a very narrow rim within the labial rib : inner lip broad and 

 thick, reflected on the pillar, and united with the outer lip at 

 the upper corner of the mouth : operculum pale horncolour, 

 with a short lateral spire, and very delicately striated. L. 

 0-215. B. 0-15. 



Habitat : Lower part of the littoral zone in the 

 Channel Isles, and on the coasts of Dorset, Devon, and 

 Cornwall ; bv no means common. It has also been 

 found at Margate (Hanley), Tenby (Lyons), Arran 

 Isles, co. Galway (Barlee), Miltown Malbay, co. Clare 

 (Harvey, fide Thompson), Bantry Bay (J. G. J.), Dublin 

 Bay (Waller), off Larne, co. Antrim (Hyndman and J. 

 G. J.), Cnmbrae, Arran, N.B. (J. Smith), Lamlash Bay 

 (Norman) . Fossil in a bone-cavern at Mardolce in 

 Sicily (Philippi) . North and west of France (De Ger- 

 ville, Cailliaud, and others) ; Cadiz (M f Andrew) ; south 

 of France (Michaud and others) ; Dalmatia (Brusina) ; 

 Spezzia (J. G. J.) ; Naples (Scacchi, fide Philippi). 



This, as well as R. cancellata, adheres with some 

 tenacity to the stones on which it is found ; and when 

 detached it also spins a fine byssal thread, by means of 

 which it suspends itself in the water. The carving of 

 the shell is inimitable. One of my specimens (probably 

 a male), although full-grown, is little more than three- 

 quarters of a line in length, and of proportionate breadth. 



