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 preserved from 

 slipping backward, while by the action of its mus- 

 cular power, it throws the shell forward. The 

 peculiar habits of the Solen render only perpen- 

 dicular motion necessary to it, and the form 

 of its shell, and the powers with which it is gifted, 

 are admirably calculated for movement in this 

 direction, but it is unable to advance horizon- 

 tally. 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 depression on 

 the sand ; sometimes the shells are dug out by 

 the fishermen, but as this is a laborious employ- 

 ment, they are often entrapped by stratagem. 

 For this purpose, at the reflux of the tide, when 

 the men can approach them, a little salt is placed 

 round their perforations, this melting, is mistaken 

 by the animal for the return of the tide, and thus 

 decoyed, they elevate themselves in the expecta- 

 tion of finding their prey. So rapid, however, 

 are their actions that great dexterity is requisite 



