338 THE PHILOSOPHY 



mufcles, and iLould be carefully pulled ofF before the animals are 

 thrown into the ftomach. 



Other blvalved fhell-fifhes, the fpecies of which are numerous, 

 perform a progreffive or retrograde motion by an inftrument that 

 has no fmall refemblance to a leg and foot. But the animals can, 

 at pleafure, make this leg affume almoft every kind of form, accor- 

 ding as their exigencies may require. By this leg they are not on- 

 ly enabled to creep, to fmk into the mud, or difengage themfelves 

 from it, but to perform a motion, which no man could fuppofe fhell- 

 fiflies were capable of performing. When the tellina, or limpin, is 

 about to make a fpring, it puts the fhell on the point or fummit, as 

 if with a view to diminifh fridlion. It then ftretches out the leg 

 as far as poffible, makes it embrace a portion of the {hell, and, by a 

 fudden movement, fimilar to that of a fpring let loofe, it ftrikes the 

 earth with its leg, and actually leaps to a confiderable dillance *. 



The fpout-fifh f has a bivalved fhell, which refembles the handle 

 of a razor. This animal is incapable of progreffive motion on the 

 furface ; but it digs a hole or cell in the fand, fometimes two feet in 

 depth, in which it can afcend and defcend at pleafure. The inftru- 

 ment or leg by which it performs all its movements is fituated at 

 the centre. This leg is flefhy, cylindrical, and pretty long. When 

 necelTary, the animal can make the termination of the leg affume 

 tlae form of a ball. The fpout-fifli, when lying on the furface of 

 the fand, and about to fink into it, extends its leg from the inferior 

 end of the fliell, and makes the extremity of it take on the form of 

 a fliovel, fharp on each fide, and terminating in a point. With this 

 inftrument the animal cuts a hole in the fand. After the hole is 

 made, it advances the leg ftill farther into the fand, makes it affume 



the 



* Oeuvres de Bonnet, torn. 5. pag. 341. 4to edit, 



I The name of the animal in Scotland. In England it is called razor-fijk. 



