60 CLASSIFICATION AND CRIATION. 



however, a connection with his past home bj a 

 siphon that runs through the whole succession 

 of chambers. The readers of the "Atlantic 

 Monthly'" cannot fail to remember the exquisite 

 poem suggested to the Autocrat of the Break- 

 fast-Table by this singular feature in the struc- 

 ture of the so-called Chambered Shells. 



Cuvier divided the Mollusks also into a larger 

 number of classes than are now admitted. He 

 placed the Barnacles with them, on account of 

 their shells ; and it is only since an investigation 

 of the germs born from these animals has shown 

 them to be Articulates that their true position is 

 understood. They give birth to little Shrimps 

 that afterwards become attached to the rocks 

 and then assume the shelly covering that has 

 misled naturalists about them. They ought 

 therefore to be referred to the class of Crus- 

 tacea, in which they are now generally included. 

 Brachiopods formed another of his classes ; but 

 these differ from the other Bivalves only in 

 having a network of bloodvessels upon their 

 mantle, in the place of free gills, and this is 

 merely a complication of structure, not a differ- 

 ence in the general mode of execution, for the 

 position and relation of these organs to the rest 

 of the structure are exactly the same in both. 

 Pteropods constituted another class in his divis- 

 ion of the type of Mollusks ; but these animals. 



