THE GOOSE-MUSSEL, OR DUCK-BARNACLE. 



489 



We will now cast a hasty glance at the transformations through which these creatures 

 pass before attaining their perfect state. It has already been mentioned that the young 

 cirripedes are free and able to wander about at will ; and as is generally the case in such 

 instances, they are apparently of a higher organization when young than when adult. For 

 example, the young Barnacle can swim freely with certain limbs. When adult, it loses those 

 limbs. When it is young, it possesses eyes ; but when it attains maturity, it loses those 

 valuable organs, which, although indispensable to a wanderer, are needless for a being which is 

 fixed to one spot and needs not to move in order to obtain subsistence. 



When first set free from the parent, the Barnacle is extremely minute, and has a striking 

 resemblance to the young of one of the Entomostraca already described. It has three pairs of 

 legs, with imperfect joints and ending in bristle-like appendages. By the vigorous flapping of 

 these limbs the young Barnacle is driven quickly through the water, with a sharp but uncer- 



GOOSE-MUS8EL. Lepaa onoOfera. (On pumice-stone.) 



tain movement. In fact, a microscope of low power, when applied to the water wherein a 

 number of these tiny creatures are swimming, discloses a swarm of merry little beings playing 

 about just like the clouds of gnats over water, or the dancing motes in the sunbeam. 



Just in the middle of the part of the body which by courtesy we will call the forehead, a 

 single eye is placed, black, round, and shining as if it were a little jet bead inserted into the 

 body. There are also two very large antennae, which serve two useful purposes, for they aid 

 the free and imperfect Barnacles to proceed through the water, while they are the means 

 whereby the creature fixes itself to the rock when about to undergo its last change. 



IN the accompanying illustration is seen a group of the common GOOSE-MUSSEL, or DUCK- 

 BARNACLE,, so called on account of the absurd idea that was once so widely entertained, that 

 this species of barnacle was the preliminary state of the barnacle-goose, the cirri representing 

 the plumage, and the valves doing duty for the wings. 



This Barnacle is tolerably universal in its tastes. It clings to anything, whether still or 

 moving, and is the pest of ships on account of the pertinacity with which it adheres to their 



Voi.Ui.-62. 



