ON 



THE NERYOUS SYSTEM 



OF 



RANA PIPIENS, LIN. 



THE following memoir comprises an anatomical description of the nervous sys- 

 tem of a single species of Batrachian Reptiles, one of the largest existing represent- 

 atives of the Anourous group. The peripheral portion especially is described some- 

 what in detail ; likewise some of the changes which it and the nervous centres 

 undergo during the process of metamorphosis. A comparison is made between the 

 temporary conditions of some of the organs, as observed in the young, with the 

 permanent conditions found in the class of Fishes, from which it appears that 

 there exists a more complete analogy between some of the anatomical condi- 

 tions of this class and the Iarva3 of Batrachian Reptiles, than has been generally 

 recognized. 



In drawing up the descriptive details of this memoir, there are many which have 

 been already noticed in other and allied Reptiles ; nevertheless, they are drawn from 

 a species whose anatomy has not as yet been fully described, and which in some 

 respects differs from that of the closely allied species ; it is therefore probable, 

 that the want of agreement between the results contained in this memoir and 

 those of other anatomists whose works are quoted, is dependent upon specific 

 differences. 



In the details relating to the cranial nerves, there are some facts noticed, which 

 have not only a bearing on their physiology, as in the case of the facial nerve, but 

 upon the philosophical anatomy of the nervous system, and the reduction of all 

 of the cranial nerves, except those connected with the organs of the special senses, 

 to the common spinal type. 



The nervous system of Batrachian Reptiles is worthy the attention of the anato- 

 mist, on account of the great simplicity of its structure, presenting a condition in- 

 termediate between the two extremes of the Vertebrate series, as exhibited by that 

 of the higher Mammals, on the one hand, and that of the Cyclostome Fishes and 

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