and its Natural Affinities. 365 



" Recueil d'Observations de Zoologie et d' Anatomic comparee " 

 of the Voyage of Humboldt and Eonpland*. The title of this 

 memoir gave occasion to naturalists to make use of the term 

 " doubtful reptiles " to indicate this group. That which was 

 then doubtful is not so^ however^ at the present day. Doubts 

 there will always be : what field of human research is free from 

 them ? but these doubts at present affect other points. That 

 which was then unascertained, and which Cuvier sought to de- 

 termine, was whether the reptiles with branchiae were not larvse 

 destined to lose those organs. He examined the Axolotl, of 

 which Humboldt had given him two specimens which he had 

 brought from Mexico, and he compared it with the Siren of 

 South Carolina and the Proteus of the lakes and subterranean 

 waters of Carniola and Dalmatia. All these animals possessed 

 branchise and lungs. 



As the result of his researches, Cuvier was convinced that the 

 Siren and the Proteus were adult animals, always retaining the 

 double organs of respiration f, while he i-egarded the Axolotl as 

 the larval state of some large unknown Salamander {. Sub- 

 sequently, however, he placed the Axolotl among the genera 

 with permanent branchiae, along with Proteus and Siren^. 



To these three species, which form as many genera, we must 

 now add some others, coming, like the Siren and Axolotl, from 

 North America. But, besides these genera with persistent gills, 

 we cannot refuse a place in this natural group for certain animals 

 very similar, but in which we find no gills, although there is a 

 branchial orifice on either side of the neck. A large reptile of 

 this division was already known to Cuvier when he published 



* I., Paris, 1811, pp. 93-126: "Recherches anatomiques sur les Rep- 

 tiles regardes encore comme douteux par les naturalistes, faites a I'occasion 

 de I'Axolotl rapporte par M. de Humboldt du Mexique." This was read 

 at the Institut National, January 19 & 26, 1807. 



t Prof. B. Smith Barton had independently arrived at the same convic- 

 tion. — 'Some Account of the SJrere Zacer^/na '(Philadelphia,1807),a6rocAMre 

 in the form of a letter to J. G. Schneider, and of which only fifty copies 

 were printed, one of which I obtained at the sale of Blumenbach's library. 



X hoc. cit. p. 116. This was still the opinion of Cuvier when he pub- 

 lished the first edition of his 'Regno Animal' (1H17, ii. p. 101). 



§ Regne Animal, 2nd ed. 1827, ii. p. 119, note: ''So many persons 

 affirm tliat it does not lose them, that 1 feel obliged to acquiesce." How- 

 ever, more recently still, the distinguished American, Spencer Baird, re- 

 tained similar doubts (Journ. Acad. Nat. Sc. of Philadelphia, Oct. 1849, 

 vol. i. ser. 2. p. 281, "Revision of the North American Tailed Batrachia"). 

 The author expresses himself as follows : — " It is only because there is no 

 positive proof to the contrary that I retain the genus Siredon as real, 

 placing it at the bottom of the series. It so much resembles the larva of 

 Ambystoma punctata, in both external form and internal structure, that I 

 cannot but believe it to be the larva of some gigantic species of this genus" 

 (p. 292). 



