47. A keyhole limpet, Diodora aspera, 3 

 inches long, micovered at a veiy low tide. 

 By means of its muscular foot it clings to 

 the rock, even in strong surf, from Alaska to 

 Lower California. The ribbing of the shell 

 is obscmed bv a calcareous growth. (Ore- 

 gon. Ralph Buchsbaum) 



48. In the giant keyhole limpet, Mcgtithiiia crcnulata, 7 inches long, the 

 black, velvetv mantle partly covers the oval shell. Found on the open coast, 

 it is shown here in an aquarium. (Cy La Tour and Marineland of the Pacific) 



■'*S«fA 



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