A GROUP OF SAND-DWELLERS. 93 



it has various names in the north, where it is dug 

 out of a very deep burrow in the sand and mud. 



If you wish to know its true name, you can look 

 at the list of Names of Figures, at the end of this 

 book. But it is very proper to call it a giant; for 

 when you are making soup, you must remember 

 that it would take more than a thousand of the 

 little Wedge-shells to fur- 

 nish as much meat as is 

 contained in a single 

 Giant Clam. 



There is just one more , 

 sand-dweller that we will I 

 think of to-day, and he 

 is very different indeed 

 from those we have been 

 considering. His picture 

 is given in Figure 47, but Figure 47. 



that shows only the shell when the animal has 

 gone inside and has pulled in his door, or opercu- 

 lum, as it is called. 



The shell is so big and round that it is some- 

 times called the Moon-shell, though its color is 

 not pure white, but somewhat spotted like the real 

 moon. Sometimes it grows to a size three or four 

 times that of the picture. 



When the mollusk comes out of his shell he 



