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 ridge : 

 spire rather short, abruptly pointed : ivhorls 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 slightlv 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, fide Brown) , Aberdeenshire (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 (M f 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. cyclostornata of Recluz, R. ob- 

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

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

 Philippi. 



