172 



the lašt whorl from the labrum, about 0*015, and then convexly 

 rounded esternally and concaTely internally ; widely expanded, de- 

 flected below, subsemielliptical. Labrum, leaves the body at about 

 50°, very mucb tliickened and reflected ; pure white ; deeply scol- 

 loped by the strong spirai carinse, whicb form five blunted points. 

 Labium *, nearly straight above, curved below abruptly to the right 

 and then to the left back agaia ; nrnch below the plane of the labrum, 

 joining it at about the constriction of the aperture above, but rising 

 to the plane below. Umbilicus, narrow and deep. Labral lamella, 

 very slightly rounded, and projecting at its junction with the labrum, 

 narrow and slightly produced below. Ojjerculum, very broadly 

 margined all round by a wide convex fold and a raised lamella on 

 the labral side likę the capital italic D ; very deeply coucave, with, 

 in the hollow, three or four rounded raised ridges crossing diagonally 

 from right above to left belovv^, vehich are finely decussated diagonally 

 from left to right, the labral side finely plaited, the lower left end 

 expanding broadly, and folding over the lovver part of the labium 

 in thin plaits or laminse ; which plaits are continued on the lower 

 side of the operculum. A very interestiaig shell. 



Height 0-039, greatest breadth 0-074, least breadth 0-053. 



Named in honour of Sir Robert Schomburgk, the celebrated 

 traveller in Guiana, and great naturalist, &c. 



WiLKiNSON^A Abbottiana, Chitty. 



Hab. ? Hanover. 



Form, subdiscoidal. Colour, white, subtransparent, shining. 

 Sculpture, five very strong spirai carinse, with, at the periphery, two 

 highly microscopic, scarcely visible, intervening the strong lines ; 

 three rather stronger, belovv the lowest strong carina round the um- 

 bilicus ; one strong on the upper whorls. Spire, niuch depressed, 

 with convex outlines. JVhorls, 4, very slightly rounded, with a light 

 suture. Aperture, extraordinarily produced from the body-whorl, 

 rather constricted far away from the labrum, and rather cupped 

 inwards to the labrum ; flattened above, expanded and depressed 

 below, semielliptical. Labrum, extraordinarily produced and de- 

 pressed at the uppermost strong spirai carina, slightly scolloped and 

 pectinated at and by the other strong carinse, reflected and thickened 

 slightly. Labium, widely detached from the body-whorl, very little 

 curved to the right below, very much below the plane of the labrum. 

 Umbilicus, shallow and broad. Labral lamella, slightly and angu- 

 larly spread out close to the labrum, then thin and narrow and not 

 concealing the umbilicus. Operculum, most extraordinary, and who 

 can describe it ? ! Very deeply concave in the middle, with a broad 

 raised margiu all round, very broad and much rounded on the labial 

 side, which has a largely developed tooth-like horizontai plait or fold 

 half-way down it descending into the hollow, and a much larger one 

 proceeding from the loveest labial side, flovnng, as it were, to the left 



* It is singular, that out of only ten specimens, every one shouid have the 

 operculum which partially hides the labium. 



