Z*^ COl^GEYUA—DITHYRA. 14. 



Shell oblong, angular and truncate at the anterior end, with a notch 

 on the teeth at the the broader end. 



Tab. nost. 4, fig. 3. The young shell. 

 Mya pubescens. Montagu, Test. Brit. p. 40. 



Turton, Conch. Diet. p. 99, fig. 35. 

 Mya declivis. Linn. Trans, viii. p. 36. 



Dorset Catal. p. 27j tab. 4, fig. 6. 

 Wood, Conch, p. 93, tab. 18, fig. 3. 

 Mus. nost. Torbay and Plymouth. 



Shell when full grown two inches and a half long and three and 

 a half broad, oblong, much flatter than the Anatina convexa, 

 rough, striate transversely, brownish white : beaks nearly central, 

 with the jjoints not opposite, but crossing each other at the tips : 

 teeth projecting and running obliquely to the anterior side, with 

 a cavity or notch behind and small erect denticle : inside with an 

 oblique rib from the tooth towards the truncated end. 



We have been fortunate enough to procure the intermediate sizes 

 of this species, by which we are enabled to clear up all difficulties 

 with respect to the young of the present shell; and the Mya de- 

 clivis of Montagu. 



This has the teeth oblique, as may be observed in our plate ; and 

 the Mya declivis has the teeth projecting inwards and oval, as may 

 be seen in Montague's plate 1, fig. 2. 



tnincata, Anatina testd conveocd cuneatd, latere postico truncato, umbonihus 

 subterminalibus. 

 Shell convex wedge-shaped, truncate at the hinder end, with the 

 beaks nearly terminal. 



