114 NATURAL HISTORY OF OUR SHORES 



It is sometimes found at low water, living in rock crevices, 

 among nullipores, etc. 



The common little " Acorn-barnacles," that coat the 

 rocks in every situation, from the sun-scorched ranges at 

 high-tide level to deep water, and that are also attached 

 to stones, shells, the backs of crabs, and everything else 

 that has a surface, also belong to the Cirripedia. 



Many young visitors (and, I am afraid, some of their 



Fig. 45. Nauplius and Cypris of ship-barnacle 

 Much enlarged 



seniors) to the shore mistake these little things for young 

 limpets with the tops of their shells rubbed off. 



However different these may appear outwardly their 

 interior anatomy and their development is the same as 

 that of the ship -barnacle. The differences are that the 

 " stalk " is suppressed, and replaced by a shelly disc, and 

 that the outer shells are modified into a pyramidal form. 

 On looking at a specimen from the top the movable 

 valves, like those of Lepas, are easily seen. 



