78 Zoological Society. 



right. Umbiliciis, very deep and suddenly narrowed. Labral lamella, 

 very strongly produced close to the labrum above, less prominent 

 round the iirabilicus. Operculum, slightly concave in the middle, 

 with a deej) broad margin all round, very fine granulations in the 

 hollow, with (?) four very fine distant carinse crossing diagonally 

 from right above to left below. 



Height 0-04, greatest breadth 0-06G, least breadth 0-053. 



Named in compliment to the memory of the late Mr. David Dyson 

 of Salford, so well known for his zoological researches in Central 

 America, Venezuela, &c. 



WiLKiNSON^A Hanleyana, Chitty. 



Huh. Pool's Rock, Hanover. 



Form, subdiscoidal, or very depressed conic. Colour, pale horn. 

 Sculpture, lines of growth, wide apart : 3 strong spiral carinse ; 

 4th, stronger ; 3 strong ; 8th, stronger ; 3 strong ; 1 2th, stronger ; 

 3 strong; 16th, stronger; 2 strong; 19th, stronger; and 4 strong 

 round the umbilicus. On the upper whorls, 3 strong ; 1 stronger ; 

 and 3 strong. Spire, slightly elevated, with straight or very slightly 

 concave outlines. Whorls, 3\, well rounded with light suture. 

 Aperture, much constricted behind the labrum, and then much di- 

 lated ; depressed above and expanding below ; subsemicircular. La- 

 brum, double, slightly produced above ; pectinated and slightly scol- 

 loped by the five stronger carinse ; attached to the body-whorl and 

 produced at an angle of about 70° ; slightly thickened and reflected. 

 Labium, much lower than the plane of the labrum above ; less so, 

 below, moderately detached from the body-whorl ; rather curved at 

 both extremities. Umbilicus, shallow and broad, not aft'ected by the 

 labral lamella, which is fine and narrow throughout. Operculum ? 



Height 0-041, greatest breadth 0-061, least breadth 0-047. 



Named in compliment to Sylvanus Hanley, Esq., author of ' Bri- 

 tish Shells,' &c. 



WiLKiNSON.EA Bensoniana, Chitty. 



Hab. Roaring River, Westmoreland. 



Form, subdiscoidal. Colour, rather dark brown. Sculjiture, six 

 prominent sharp spiral carinse intermingled with eighteen less strong : 

 on the upper whorls, one strong between about six less strong. 

 Spire, very little elevated, with slightly concave outlines. Whorls, 

 'i\, slightly rounded with a very light suture. Aperture, semicir- 

 cular, depressed above in the vippermost third, much expanded 

 below. Labrum, much and pointedly produced above, at an angle 

 of about 75° from the body-whorl, white, slightly thickened and re- 

 flected, angulated, not pectinated, by all five pohits of the sharper 

 carinse. Labium, rather curved below, much detached from body- 

 whorl, on a plane with the labrum at the lower end, much below it 

 above. Umbilicus, rather deep and broad. Labral lamella, regu- 

 larly produced, strong but narrow, subangularly pointed close at the 

 labrum. Operculum, moderately concave, serpentine on the labial 

 side, with a groove on the labral side. 



Height 0-027, greatest breadth 0-049, least breadth 0-038. 



