b LITTORIXID.E. 



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

 sometimes double, or else having a vaiix 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 : s/)//v 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, occuppng 

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

 somewhat acutely above and obtusely below, and slightly ex- 

 panded outwards ; inside plain : outer Up semicircular, forming 

 a very narrow rim vrithin 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 homcolour, 

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

 0-215. B. 0-1.5. 



Habitat : Lower part of the littoral zone in the 

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

 Cornwall; by no means common. It has also been 

 found at Margate (Hanley), Tenby (Lyons), An'an 

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

 (Hai'vey, ^^f/e Thompson), Bantry Bay (J. G. J.), Dublin 

 Bay (WaUer), off Larne, co. Anti'im (Hyndman and J. 

 G. J.), Cumbrae, 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- 

 viUe, Cailliaud, and others) ; Cadiz (M'^ Andrew) ; south 

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

 Spezzia (J. G. J.) ; Naples (Scacchi,/f/e 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 thi'ce- 

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



