54 ANIMAL PARASITES AND MESSMATES. 



much changed them, that Cuvier and all the zoologists 

 of his age placed them in the class of mollusca. The 

 incrustations of their skin resemhled shells, which these 

 creatures generally carry in the suhstance of their 

 mantle. 



These amhiguous creatures are far from heing micro- 

 scopic ; there are Balani which attain the size of a 

 walnut, and some have heen found not less than ten 

 inches high, as the Balanus psittacus. . Some years Bince 

 we saw on a piece of floating wood, found by fishermen 

 in the North Sea, Anatifae on the end of stalks from 

 six to seven feet in length. The anatifse themselves 

 were of the usual size. These cirrhipedes belonged to 

 every geological period ; they have already been found 

 in the Silurian formation, but, unlike the trilobites their 

 contemporaries, they pass through all the ages, and, far 

 from decreasing, they reign as masters at the present 

 time in the two hemispheres. 



It was an English naturalist, Thomson, who first 

 made known the true nature of these singular organ- 

 isms. So far were many from understanding their 

 affinities with the other classes, that even after the 

 excellent researches of the Belfast naturalist, they 

 doubted their correctness, and .supposed that these 

 animals were allied both to the mollusca and to the 

 articulata. 



We see by this the immense progress which embryo- 

 logical studies have caused us to make in the apprecia- 

 tion of natural affinities. No one at the present time, 

 who has seen a cirrhipede hatched, can retain any doubt 

 as to the place which it ought to occupy. These crusta- 

 ceans, taken as a whole, lead a life in which we find 



