MYA GAPER. 147 



The circumference. 



The muscular impressions, marks in the inside 

 of the shell made by the adhesion of the adduc- 

 tor muscles. 



The right valve, the valve nearest to the right 

 hand, when the shell is placed on its base with 

 the area opposite to the person looking at it. 



The left valve. 



The teeth, pointed protuberances at the hinge. 



The cardinal teeth, the central teeth, or those 

 near the centre of the hinge. 



The lateral teeth, the teeth near the sides. 



GENUS. MYA.* 



GAPER. 



Generic character. Shell bivalve, equivalve, 

 inequilateral, sometimes gaping at one end, 

 sometimes at both ; shape suboval, broader than 

 it is long ; generally smooth, or only slightly 

 striated ; hinge with a thick, strong, patulous,^ 

 or spoon-shaped tooth, sometimes inserted into 

 the opposite valve. 



OBSERVATIONS ON THE SHELL AND ITS 

 INHABITANT. 



The points of generic resemblance in the Myae 

 are wanting in many of the species. The coarse 



* Plate VII. fig. 1 , 2. 



t Patulous, lying open, spreading, from the Latin, pat ere, to 

 Jie open. 



