ASTAETE. 



125 



or pitcliy ; concentric waves not numcrons (al)oiit twenty), large 

 except on the beaks, recurved, and often quite wanting near the ven- 

 tral margin, and along the posterior slope ; this absence of folds is 



Fig. 435. 



Fig. 436. 



A. elliptica. 



A. elliptica. 



Fig. 4.37. 



A. elliptica. 

 Young. 



often quite remarkable, even in young shells. Fine concentric lines 

 are generally found on l)oth ril)s and interspaces. Tlie hinge-mar- 

 gin is quite narrow and delicate, as the beaks do not 

 rise to a point so as to form a large triangular area for 

 the hinge, and the teeth are by no means conspicuous 

 and robust; color of interior a dead livid or leaden 

 color ; muscular and pallial impressions large and 

 deep ; inner margin always simple. 



The elongated, elliptical form, usual disappearance of waves near 

 the ventral margin and rear, delicate hinge and hinge-margin, 

 dingy-white or livid interior, and simple inner margin at the most 

 antiquated stages, are quite enough to determine the specific value 

 of this shell. 



Astarte Banksii. 



Shell small, elevated, heart-shaped, tumid ; beaks acute, anterior margin exca- 

 vated, lunule deep and broad, surface with croAvded, well-defined waves, inner 

 margin smooth. 



Astarte Bunksii, Leach, in Ross's Voy. Appendix. — Gray, Zool. Beeclicy's Voy. pi. 44, 

 fig. 10. — SowERBT, Thes. Conch, ii. 782, pi. 167, fig. 8. 



Shell quite small, ovate-triangular or ol)liquely heart-shaped, tu- 

 mid ; beaks nearly median, prominent, acute, pointing 

 forwards, the lunule broad and deeply excavated ; an- 

 terior dorsal slope concave, sometimes remarkably so, 

 rendering the anterior ])ortion much less elevated and 

 smaller than the posterior, and forming an angle as it 

 joins the well-rounded end, which curve passes into 

 that of the gently curved base ; posterior dorsal margin 

 always very slightly swelling, though nearly direct, but rapidly de- 



A. Banksii. 



