SOLEN RAZOR SHELL. 155 



advances the leg a little farther, fixes it by its 

 point as a hook in the ground, and using this as 

 a fulcrum, descends in safety, continuing the 

 operation till the shell is buried about two 

 inches under ground. When it wishes to regain 

 the surface, the leg is rolled up into a spherical 

 form, and stretched very tight ; by means of 

 the ball thus formed, the little creature is pre- 

 served from slipping backward, while by the 

 action of its muscular power, it throws the shell 

 forward. The peculiar habits of the Solen 

 render no other than perpendicular motion neces- 

 sary to it, and therefore while the form of its 

 shell, and the powers with which it is gifted, are 

 admirably calculated for movement in this 

 direction, it is unable to advance horizontally. 

 It requires a safe retreat and a supply of food ; 

 the former it obtains by withdrawing into its 

 recess, and the latter by ascending its channel 

 when the tide comes in and brings the little 

 marine insects which form its food. The 

 retreat of the Solen is marked by a small de- 

 pression on the sand ; sometimes the shells are 

 dug out by the fishermen, but as this is a labo- 

 rious employment, they are often entrapped by 

 stratagem. For this purpose, at the reflux of 

 of the tide, when the men can approach them, a 

 little salt is placed round their perforations, 

 which melting, is mistaken by the animal for 

 the return of the tide, and thus decoyed, they 

 elevate themselves in the expectation of finding 

 their prey. So rapid, however, are their actions 



