ANIMAL KINGDOM. 313 



to the Radiata, and that the transition from one to 

 the other is effected by means of the Cirripeda. The 

 principal deviation from this line of affinity will be found in 

 the structure of the shell of these last, which, while it differs 

 from that of the Mollusca, appears by no means perfectly to 

 correspond with the external covering of the Radiata. 



Of the method in which the Crustaceous animal dis- 

 appears, and leaves the structure of Echinus only appa- 

 rent, I am at present totally ignorant; but it will be 

 sufficient for my purpose to prove that the Cirripedes have 

 a nearer affinity to the Echini than to any other tribe of 

 animals except the Crustacea. The operculum of a Ba- 

 lanus, the complicated structure of its valves, and the 

 method by which they are affixed to the radiated cone 

 which contains the animal, have no affinity to any thing in 

 nature, unless it be to what we may witness on examin- 

 ing the mouth of the Echinidec. The porous nature and 

 radiated structure of the outer shells, with the solid calca- 

 reous substance of the inner ones, correspond in both the 

 Cirripede and Echinus. — Their common hermaphrodi- 

 tism and the peculiar disposition of their ovaries afford 

 additional proofs of their affinity; and it is not a little re- 

 markable that the older naturalists, such as Linnaeus, 

 Bruguieres, Klein, and Muller, placed the Echini as well 

 as the Cirripedes among the Mollusca, although merely, as 

 it would appear, because they have all a calcareous cover- 

 ing. That they had any more profound view is doubtful, 

 from their interposing Chiton between Echinus and Lejjas. 

 M. de Blainville indeed considers the genus Chiton to 

 form one group with the Cirripedes ; but as he then passes 

 from these to Lepidopterous insects, we may be permitted 



