CONCHIFERA OR BIVALVES. 69 



small foot from the other. — 4 species, re- 

 cent. 



One end of this shell gapes very much, and 

 at the aperture the thick epidermis is length- 

 ened out into a tube, which can be withdrawn 

 at pleasure by the animal. This mollusc buries 

 itself in the sand, allowing the tube just to 

 reach the surface, and by the aid of the smaller 

 tubes contained within it procures its food. It 

 is found on the shores of the European, Asiatic, 

 and African seas, and is used as an article of 

 food in several places ; it is also devoured by 

 marine birds. 



20. Anatina. — Shell transverse, thin, and 

 almost transparent, 

 gaping at one or both 

 ends, having a spoon- 

 shaped tooth in each 

 valve, and a small 

 moveable appendage connected with the in- 

 terior of the hinge. The tooth in each valve 

 is supported by a thin small plate ; ligament 

 internal. Animal, foot tongue-shaped. — 10 

 species, recent. 



These shells are found in India, New Hoi- 

 F 3 



