[ 3^5 1 



THE RAZOR-SHELLS*. 



These shells are bivalve, oblong, in shape 

 somewhat resembling the handle of a razor, and 

 open at both ends. The hinge has a small and 

 sharp reflected tooth, sometimes double, not in- 

 serted into the opposite valve. The animal is simi- 

 lar to that of the last tribe. 



Many of the bivalved shell-fishes have the power 

 of performing a progressive or retrograde motion, 

 by an instrument that has some resemblance to a 

 leg or foot, and called the tcngue. But the present 

 animals can, at pleasure, make this assume almost 

 every kind of form, as their exigences require. 

 By this tongue they are not only enabled to creep, 

 to sink into the mud, or disengage themselves 

 from it, but to perform a motion which no one 

 could suppose shell fishes were capable of per- 

 forming. 



All the species of Razor-shells are incapable of 

 progressive motion on the surface ; but they dig a 

 hole or cell in the sand, sometimes two feet in 

 depth, in which they can ascend or descend at plea- 

 sure. The instrument or tongue, by which they 

 perform all their motions, is situated at the centre. 

 It is fleshy, cylindrical, and tolerably long. When 

 necessary, the animals can make the termination of 



* Solen. Linn, 



Oos 



