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CLASS V. CIRRIPEDIA. 

 (BARNACLES.) 



AT first sight no two objects can well be more 

 unlike than a Barnacle and a Shrimp. The former 

 is enclosed in a true shell composed of many pieces 

 united either by shelly matter or by cartilage, 

 which allow of the protrusion and retraction of a 

 hand of fine hairy filaments, the whole permanently 

 affixed to foreign objects either by a thick, flexible 

 stalk, or by a broad, immoveable base. The older 

 naturalists associated these animals with the shell- 

 bearing MOLLUSCA, calling them Multivalves, and 

 even up to very recent times they have been con- 

 sidered as equally allied, to the Sub-Kingdom just 

 named and to that in which they occur here. Mr. 

 Charles Darwin, however, in his admirable Mono- 

 graph, has fully demonstrated the close affinity 

 which subsists between them and the CRUSTACEA, 

 of which he, indeed, considers them only a sub- 

 division. I prefer, however, to treat them as a 

 Class by themselves, believing that the diversity 

 between the groups is quite as great as that 

 which subsists between the CRUSTACEA and the 

 ARACHNIDA, or between the ARACHNIDA and 

 the INSECTA. 



The Barnacle begins life in a form exactly like 

 that of a young Entomostracous Crustacean, with a 

 broad carapace, a single eye, two pairs of antennae, 

 three pairs of jointed, branched, and well-bristled 

 legs, and a forked tail. It casts off its skin twice, 





