MYA GAPER. 149 



derably, curved at the areola, wrinkled trans- 

 versely, and covered with a brownish yellow 

 tough epidermis, extending an inch or two be- 

 yond the gaping end, like a thick membrane, 

 through which the animal protrudes its tube ; 

 hinge with a rounded tooth projecting forwards ; 

 inside white ; length from one to two inches ; 

 breadth from two to three. 



These shells inhabit the sand or gravel about 

 low water mark on most of the northern coasts 

 of Europe. In Greenland their mollusca are 

 the food of man and other animals. When taken 

 alive, the epidermis of the shell is found joined 

 to the tube or proboscis of the animal, having 

 become a thick, tough, coriaceous* skin for its 

 protection. The animal is capable of extending 

 this tube to the distance of nine or ten inches, 

 and of contracting it to about three, but cannot 

 withdraw it entirely into the shell. 



MYA Marga atifera. 

 PEARL-BEARING OYSTER. 



Specific character. Shell strong, ponderous, 

 thick ; shape ovate, oblong, front compressed, 

 margin a little contracted in the middle, giving 

 a somewhat curved outline to the circumference ; 

 hinge consisting of a cardinal tooth in one valve, 

 which is thick, obtusely conical, and locking into 



* Coriaceous, like leather, derived from the Latin con wm, skin, 

 leather. 



13* 



