SECOND GREAT DIVISION OF THE ANIMAL 

 KINGDOM. 



ANIMALIA MOLLUSCA(l). 



The Mollusca have neither an articulated skeleton nor a 

 vertebral canal. Their nervous system is not united in a spinal 

 marroW;, but merely in a certain number of medullary masses 

 dispersed in different points of the body, the chief of vvhich^ 

 termed the brain^, is situated transversely on the (Esophagus, 

 and envelopes it with a nervous collar. Their organs of motion 

 and of the sensations have not the same uniformitv as to num- 



(1) That portion of the Baron's Avork which relates to the Molhisca, and with 

 which he commences the third volume of his last edition, is preceded by a few re- 

 marks in the shape of a preface. As I have replaced this division, as well as that 

 of the Zoophytes, in their proper situation, it is impossible to give that preface 

 without creating- an awkward break in the series. Besides this, it contains but little 

 of moment. The author merely states the reasons which delayed the publication of 

 the third volume for a long time after the appearance of the fourth; among- the most 

 prominent of which were the number of changes in the genera, and in the distribution 

 of species, he was compelled to make by recent discoveries. He also acknowledges 

 his obligations to the works of tlie late lamented M. de Lamarck, and those of 

 MM. de Blainville, Savigny, Ferrussac, Des Hayes, D'Orbigny, Rudolphi, Bremser, 

 Otto, Lcuckart, Chamisso, Eisenhardt, Rang, Sowerby, Charles Desmoulins, Quoy 

 and Gaymard, Delle Chiaje, Defrance, Deslonchamp, Audouin, Milne Edwards, 

 Duges, Moquin Tandon, Morren, Ranzani, and other savans whom he names in 

 different places. He concludes by regretting that he had not received in time cer- 

 tain very recent works, which would have supplied him with valuable materials, 

 particularly the Sysi. Acaleph-, Berlin, 1829, 4to, of M. Eschholtz.and the article 

 Zoophytes of the Diet. desSc. Nat., of M. de Blainville, which was not then pub- 

 lished. Am. Ed. 



