39 



ny be considered the width, is in fact the length of the 

 shell, and is consequently very small. The two valves 

 are equal, and when closed resemble a flattened cylin- 

 der, truncated at both ends, sometimes a little curved ; 

 they are united by a hinge, more frequently lateral than 

 in the middle of the lower margin, and sometimes it is 

 situated very near one of the extremities. When open, 

 the shell exhibits two or three small recurved teeth, 

 often placed at the extreme edge of the truncated extre- 

 mity, but more frequently at a short distance from it; 

 they join laterally when the valves are closed, but do 

 not enter the cavities apparently formed to receive them. 

 The apices are very small and scarcely perceptible; the 

 ligament external and near the hinge: in some species 

 there is a callosity to which the ligament is attached. 



The Solenes inhabit the sand of the sea shore, which 

 they sometimes penetrate to the depth of two feet in a 

 verticle direction, and there remain stationary ; the ani- 

 mal only quitting the thell and returning to the surface 

 in search of food, which it effects by an extension of 

 the muscular foot affixed to the further extremity of the 

 shell. Some species have their valves much longer, 

 narrower, and flatter at the extremities, as the Solen 

 Diphos, (S. llostratus of La Marc k), in which the cal- 

 losities at the hinge are also very visible. 



