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 



v * 



cir. fn.b. ci. a'. 



FIG. 12. Two stages in the growth of the Common Barnacle 

 from the Nauplius stage. Diagrammatic. 



cir. t the double legs or cirri; m, mouth; o, the single eye; 



d, the digestive canal. 

 a 1 , 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. In 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. I o and 12); 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 



