RISSOA. 75 



The spiral carinse, with the densely disposed perpendicu- 

 lar lamellar strise, in their intervals, constitute the peculiar 

 feature of this species. The two principal keels are sharp 

 and prominent, particularly the upper one, which generally 

 curls a little upward and is not adjacent to the suture, but 

 lies about as far from it as from the second carina. These 

 two are followed on the body-whorl, at some little distance, 

 by numerous crowded spiral costae, the terminal ones of 

 which are rather further apart ; one of these ribs is gene- 

 rally apparent, also, along with the carina?, on some of the 

 smaller volutions. Occasionally a raised line or two winds 

 between the principal keels. The aperture is large, and 

 occupies about four-sevenths of the total length, and about 

 three-sevenths of the ventral area; its contour is rather 

 obliquely subovate, rounded below, but contracted above. 

 The outer lip is prominently marginated or thickened 

 behind, straightish or but little curved in the middle, and 

 well arcuated anteriorly ; its basal recession is very trifling. 

 The throat merely exhibits the indentations of the external 

 sculpture. The inner lip, which unites itself to the outer 

 one by a broad parietal enamel, is very narrow on the 

 columella, where its inner edge is comparatively rectilinear. 

 There is no umbilical chink. Our largest specimens measure 

 nearly a quarter of an inch in length, and fully two lines 

 in breadth. 



The animal of this, as of too many other Risso^, is, as 

 yet, unknown. 



This is a southern species and scarce ; Island of Herm 

 on rocks near low-water-mark (S. H.) ; Margate (S. H.); 

 gathered in sand from Cornwall by Mrs. Richard Smith, 

 and at Exmouth by Mr. Clark (Jeffreys); Tenby (Lyons) ; 

 in seven fathoms, Weymouth (E. F.) ; Bantry Bay 

 (Jeffreys) ; Arran Isles, Gal way (Barlee) ; in several locali- 



