266 MARINE SHELLS 



alated angle, from which it declines also in a right 

 line, nearly to an equal distance ; alated projection 

 rounded ; anterior margin short and small ; basal 

 margin with a dilated but slightly impressed con- 

 traction in the middle ; epidermis transversely 

 wrinkled, light-brown, the raised oblique portion of 

 the shell yellowish -white ; cortex with membranous 

 scales and Aliments, and covering all the anterior 

 portion of the shell to the beak. 



Modiola i^mericana, Leach Zool. Misc. vol. 2. 

 pi. 72- fi£. 1. Var. 



Inhabits the southern coast. 



Length, from the tip of the angle to the middle of 

 the base, three-fifths of an inch nearly. 



Breadth one and one-fifth of an inch. 



Thickness half an inch. 



Cabinet of the Academy and Philadelphia Mu- 

 seum. 



This variety differs from that figured by Dr. 

 Leach, in being always destitute of oblique coloured 

 radii. 



2. M. *castaneat Shell transversely oblong sub- 

 oval ; hinge margin elevated in a right line from the 

 beak to the alated angle, from which it declines in a 

 line slightly arquated ; alated angle rounded : ante- 

 rior margin rounded at the tip ; posterior margin 

 rather large ; base with a dilated but slightly im- 

 pressed contraction before the middle; epidermis 

 concentrically wrinkled, castaneous ; cortex not con- 

 tinued behind the middle of the shell ; within bluish. 



