THE CRUSTACEANS 



81 



the males are minute, degenerate creatures without shells, mouth or 

 intestines, and live within the shell of the female. 



Fig. 4><; llock covered with KoL'k liariiacles. Cape Ann, Mass. 



The liock Barnacle, fBalanus halanoides, Fiij. 48 J, is found 

 along the Atlantic shores of Europe and America, from the Caro- 



linas northward. It lives only between 



tide levels, where it remains uncovered 

 for a considerable period each half day, 

 and is so abundant as to whiten the rocks. 

 Individuals are crowded so closelj' to- 

 gether as to become distorted and elon- 

 gated in shape. When the tide is out 

 the barnacles remain closed up, but as 

 soon as the water reaches them the lids 

 of the shells open, and the delicate I'url- 

 ing feet are thrust out at regular inter- 

 vals, sweeping food into the hungry 

 mouths of the barnacles. At the least shock or jar the 1)arnacles 

 close their lids with a snap and the waving motion ceases. 



Fig ^9-'/ Deep-watef Jiariiacle 



growing upon a stone. From 



life. Cape Ann, Mass. 



