RISSOA. 21 



minent ; its edge on the side of the mouth is furrowed or fur- 

 nished with a double ridge, the inside one of which forms the 

 outer lip ; the last four whorls are covered with spiral ridges 

 equal in size and prominence to the longitudinal ribs, and in- 

 tersecting them at a right angle, so" as to produce a series of 

 square excavations ; the points of intersection .are muricated 

 or spiky ; the last whorl has 4 of these ridges (besides that at 

 the base), each of the next two whorls has 3, and the suc- 

 ceeding whorl 2, the uppermost whorls being spirally and de- 

 licately striated ; the ridges extend to the mouth : colour clear- 

 white, sometimes golden-yellow, especially the basal~ndgo : 

 spire rather short, abruptly pointed : whorls 6-7, convex, the 

 last occupying three-fifths of the spire, the first minute and 

 rounded : suture very deep and channelled : mouth roundish- 

 oval, considerably expanding outwards : outer and inner lips 

 forming a continuous and slightly elevated rim. L. 0-125. 

 B. 0-075. 



HABITAT : Sparingly found in the coralline and deep- 

 sea zones, Guernsey (Barlee and others) , Porth Curnow 

 Cove, Cornwall (Miss Lavars), Hayle (Hockin), co. An- 

 trim (Hyndman and J. G. J.), Lamlash, Bute (Lands- 

 borough), Skye and Hebrides (J. G. J.), St. Fergus bay, 

 Peterhead (Bingham^efe Brown), Aberdeeiishire (Daw- 

 son), Caithness (Gordon), Orkneys (Thomas), Shetland 

 (Fleming and others), at depths ranging from 18-70 f. 

 Fossil in the Coralline Crag at Sutton (Wood), and in 

 the miocene formation near Vienna (Homes) . Living on 

 the coast of South Sweden, in 12-75 f. (Loven and 

 Malm), Cherbourg (Recluz), off Vigo Bay (W Andrew), 

 Antibes (Mace), Nice (Verany), and Naples (Philippi). 



With respect both to this and the next little shell, 

 we may well say with Cicero, " Quid potest esse aspectu 

 pulchrius ?" 



The synonyms are R. cyclostomata of Recluz, R. ob- 

 tusa of Brown, R. scalariformis of Metcalfe (Thorpe's 

 ' British Marine Conchology ') , and R. clathrata of 

 Philippi. - 



