BARNACLES. 



197 



-double from the basal joint outwards, while the first 

 pair are simple. In the fore part of the body a large eye 

 is placed, deep-seated, which is of a roundish form, and 

 is intensely black both by reflected and transmitted light. 

 On the summit of the forehead are placed a pair of thick 

 flexible horn-like organs, which are abruptly bent in the 

 middle, and which I believe represent the first pair of 

 antenna?. This, then, is the first stage of the Barnacle — 

 the form under which it appears when it is hatched 

 from the egg. 



YOUNG OF BAEXACLE. 



Among the multitudes which have been evolved 

 •during these last few days, and which are now swimming 

 at large in the tank, we may be able to detect some 

 that have passed through their first stage, and, having 

 moulted their skin, have attained a more advanced form. 

 Here is one, which by its superior size seems to have 

 made some progress towards maturity. 



Yes, here are more. These are evidently in their second 

 stage. There is an increase in length ; for, whereas the 



