40 THE STORY OF LIFE IN THE SEAS. 



with a multitude of firmly - fixed creatures. 

 Among them there is almost certain to be found 

 a number of small conical shells, made up of a 

 series of triangular plates, fixed to the rock by 

 their bases. These are commonly spoken of as 

 Barnacles (Balanus), and they pass through an 

 interesting history. For many years they were 

 considered, from the character of their shells, 

 to be allied to the Molluscs, but an examination 

 of the soft parts of the 

 animal shows that, 

 unlike any Molluscs, 

 they are provided with 

 six pairs of jointed 

 legs ; and a still further 

 study of their anatomy 

 proves beyond a doubt 

 that they can no longer 

 be classified, with any 

 pretence of scientific 



FIG. 11. Vertical section of a accuracy, With that 



Balanus, showing animal in situ 



in its shell. group. 



The secret of their 



true relationship was not discovered until the 

 story of the development was worked out, when 

 it was found that the eggs they discharged each 

 gave rise to a little larva called Nauplius, which is 

 provided with three pairs of legs like the larvae of 

 some of the Prawns and their allies. The result 

 of these observations then was to prove that the 

 Barnacles are really Crustaceans, notwithstanding 

 the fact that, unlike most of that group, they 

 are, in the adult stage, permanently fixed to the 

 rocks. 



