LIMA. 81 



2. L. ellip'tica*, Jeffreys. 



L. subauriculata, F. & H. ii. p. 2G3 (partly), pi. liii. f. 4, 5. 



Body pale orange: UntacuJa pale pink: foot pale orange. 

 (F. & H.) 



Shell oval or elliptical, convex, slightly and almost equally 

 expanding towards the sides, thin and glossy, semitranspa- 

 rent: sculpture, 30-40 fine longitudinal ribs, which become 

 very faint and indistinct as they approach the sides ; one of 

 these ribs, near the middle but more towards the posterior 

 side, is rather larger than the rest, and a corresponding furrow 

 is formed inside each valve, appearing outside like an oblique 

 white line; the ribs are crossed by extremely delicate and 

 numerous concentric stria^, making the crests beautifully 

 serrate ; the substance of the shell also exhibits a few diagonal 

 white streaks or lines, which diverge from the centre to each 

 side : colour pearl-white : margins broadly rounded in front, 

 and sloping with a gentle but somewhat flexuous curve up- 

 wards to the ears, much compressed at the sides: beaks ex- 

 tremely prominent and gibbous, projecting considerably be- 

 yond the hinge : ears triangular, small, erect : cartilage dia- 

 mond-shaped, occupying about one-third of the hinge, and 

 minutely striate across ; there is also a very slight and in- 

 distinct ligament on each side of the cartilage: hinge-line 

 straight except in the middle, where it is incurved to receive 

 the cartilage : hinge-plate blunt: cartilage-pit forming an ob- 

 tuse triangle, smooth ; under each ear is a shelving triangular 

 space confined below by a narrow rib : insidi highly nacreous, 

 and marked by a furrow which runs obliquely down the 

 middle, and is the reverse or under side of the larger rib on 

 the outer surface ; it is also indistinctly grooved by the im- 

 pression of the ribs ; the front margin is slightly notched by 

 the edges of those ribs : muscular sc<ir irregularly circular and 

 distinct. L. 0-55. B. 0*35. 



Var. leviuscula, JShell nearly smooth, the ribs being want- 

 ing. 



Habitat: Sandy mud, in 15-85 fathoms, off the 

 Shetland Isles and west coast of Scotland. It is not 

 uncommon in the latter district. The variety is from 



* Elliptical. 



E 5 



