216 WEST COAST SHELLS 



Others live half of their lives under water, while a few 

 must be sought at very low tide. Their dead shells 

 are very common objects along the coast, for they are 

 liable to fall victims to some wandering crab if they 

 become washed from their footing. Though they 

 creep around somewhat they usually return to the 

 same spot to roost, and the protecting shell is seldom 

 lifted to any considerable distance above the object 

 to which they cling, and when they are at all dis- 

 turbed they close it down with force and rapidity. In 

 an especial manner these helpless animals must de- 

 pend on their thick, hard shell to protect them from 

 injury. 



Acniiza spectrum^ Nutt., tne 

 Ribbed Limpet, lives far up on the 

 rocks where it receives only a few 

 splashings at high tide. It is gray in 

 color, much like the granite to which 

 it clings. Two views are given of its 

 Fig. 209 shell, both of which represent unusu- 



ally large specimens. Figure 209 

 gives a good view of the shell as it appears from 

 above, while the other figure, 210, shows a side eleva- 

 tion of the same. Internally the 

 shell is chalky-white with various 

 dark markings, which sometimes 



1 • <.!. \ m T Fig. 210 



bring out the owl very dis- 

 tinctly. Look for a picture of that bird in various 

 shells of this class. 



Limpets are easily collected if they are suddenly 

 lifted by means of a broad-bladed knife, but if they 

 have been previously startled it is best to let them 



