233 VENUS. 



heart-shaped depression under them, which with the carti- 

 lage slope is purple : hinge with three teeth in one valve, 

 one of which stands transversely $ in the other valve three, 

 besides a prominence on the side of the cavity which re- 

 ceives the transverse tooth of the opposite valve: length 

 an inch and a quarter ; breadth one and a half- 



In its contour it much resembles the V. Galiina ; but dif- 

 fers in the teeth, in having the ridges much more raised 

 and sharp-edged, lying over each other in a kind of imbri- 

 cate manner, and in the margin being quite plain. 



Dredged in the Firth of Forth : very rare. 



14. Venus triangularis. Triangular Venus. 

 Montagu, pi. 1 7. f. 3. 



Shell strong, roundish and somewhat triangular, equally 

 sloping on each side from the beaks, marked only with a 

 few antiquated ridges, of a dull yellowish-white color ; in- 

 side smooth, with the margin plain : beaks projecting in a 

 rather acute angle, giving the shell a somewhat triangular 

 outline, central, turning a little obliquely, with a lanceolate 

 depression under them : hinge stroxig, with two teeth and 

 a lateral semilunar lamina in one valve, one of the teeth 

 cloven, the other triangular and placed near it, the semi- 

 lunar lamina running parallel with the heart-shaped depres- 

 sion, its convexity pointing inwards, between which and the 

 margin is a deep groove $ in the other valve three teeth, 

 two of which diverge much, in order to admit tile triangu- 

 lar central tooth of the opposite valve, and a, lateral pne 

 locking between that and the marginal edge : length and 

 breadth abmit half an inch. 



Devonshire coast,' and Dublin bay : rare. v. in. 



15. Venus Islandica. White Clam. 



Lister, pi. 272. f. 108 Pennant, pi. 56 Da Costa, 

 pi. 14. f . 5 Donovan, pi. 77 Linn. Trans, vi. pi. 17- 

 f. 1, 2 Dorset Cat. pi. 6. f. 5. 



Shell strong, thick, convex, rounded, a little produced 

 and sloping on the cartilage side, covered when fresh with 

 a glossy yellowish-brown or dusky skin which is finely stri- 

 ate transversely, under which it is dull white and irregularly 

 striate; inside pure chalky- white, not glossy, with the margin 



plain 



