152 BIVALVES. 



OBSERVATIONS ON THE SHELL AND ITS 

 INHABITANT. 



There is generally but little difficulty in deter- 

 mining the Solenes : they are recognised by 

 their oblong form, their disproportionate breadth 

 and their gaping at both extremities. A few of 

 the species, however, are oval, and these have 

 their hinge nearly central.* 



The history of this genus affords various in- 

 stances of ingenuity in the application of very 

 simple means. The animal is furnished with a 

 long pliable cylindrical leg ; when he wishes to 

 bore a hole for his residence he extends this in- 

 strument from the inferior end of the shell, using 

 it as a pointed shovel to excavate the sand. 

 When the tunnel is partly formed, the animal 

 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 the animal wishes to re- 

 gain the surface, the leg is rolled up into a sphe- 

 rical 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 ren- 

 der 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 



* Plate VII. fig. 5. 



