112 



DIVERSIONS OF A NATURALIST 



creature except the protruding antennules with their 

 suckers. 



In this condition it swims about for a time, and then, 

 once for all, fixes itself by means of the suckers and their 

 abundant cement, on to rock, stone, or floating wood — 

 and there remains for the rest of its life (Fig. 12). It 



Fig. 12. — Two stages in the growth of the Common Barnacle 

 from the Nauplius stage. Diagrammatic. 



dr., the double legs or cirri; m, mouth; o\ the single eye; 



d, the digestive canal, 

 a', one of the antennules or " feelers " (that of the right side of 



the head) provided with a sucking disk by means of which 



the young animal becomes fixed. 



increases enormously in size, the delicate transparent 

 shell develops into hard calcareous plates, opening and 

 shutting on the hinge-line of the back. Iri the stalked 

 kinds a peculiar elongated growth of an inch or several 

 inches in length takes place between the mouth and the 

 fixed suckers of the antennules (Figs. 10 andli2); in the 

 short, so-called, "acorn" kinds, this stalk does not form, but 

 a separate part of the shell grows into a ring-like protective 



