AMPHIBIA. 143 



particular with the American genus Amblystoma. During this metamorpho- 

 sis a pulmonary respiration takes the place of a branchial one, the gills are 

 lost, and the gill slits close. The tail loses its fin and becomes rounded, the 

 colour changes, and alterations take place in the gums, teeth, and lower jaw. 



Madame von Chauvin 1 was able, by gradually accustoming Axolotl larvae 

 to breathe, artificially to cause them to undergo the above metamorphosis. 



It seems very possible, as suggested by Weismann 2 , that the existing 

 Axolotls are really descendants of Amblystoma forms, which have reverted 

 to a lower stage. In favour of this possibility a very interesting discovery of 

 Filippi's 3 may be cited. He found in a pond in a marsh near Andermat 

 some examples of Triton alpestris, which, though they had become sexually 

 mature, still retained the external gills and the other larval characters. 

 Similar sexually mature larval forms of Triton taeniatus have been described 

 by Jullien. These discoveries would seem to indicate that it might be 

 possible artificially to cause the Newt to revert to a perennibranchiate 

 condition. 



Gymnophiona. The development of the Gymnophiona is 

 almost unknown, but it is certain that some larval forms are 

 provided with a single gill-cleft, while others have external gills. 



A gill-cleft has been noticed in Epicrium glutinosum 

 (Miiller), and in Ccecilia oxyura. In Ccecilia compressicauda, 

 Peters (No. 108) was unable to find any trace of a gill-cleft, but 

 he observed in the larvae within the uterus two elongated 

 vesicular gills. 



BIBLIOGRAPHY. 

 A mphibia. 



(93) Ch. van Bambeke. " Recherches sur le developpement du Pelobate 

 brun." Memoires couronnes, etc. de F Acad. roy. de Belgique, 1868. 



(94) Ch. van Bambeke. "Recherches sur 1'embryologie des Batraciens." 

 Bulletin de I'Acad. roy. de Belgique, 1875. 



(95) Ch. van Bambeke. " Nouvelles recherches sur 1'embryologie des Batra- 

 ciens." Archives de Biologie, Vol. I. 1880. 



(96) K. E. von Baer. " Die Metamorphose des Eies der Batrachier." Muller's 

 Archiv, 1834. 



(97) B. Benecke. " Ueber die Entwicklung des Erdsalamanders. " Zoolo- 

 gischer Anzeiger, 1880. 



1 Zeit.f. wiss. ZooI.,"Bd.. xxvn. 1876. 



2 Zeit.f. wiss. Zool., Bd. xxv. sup. 1875. 



3 Archivio per la Zoologia, /' Anatomia e la Fisiologia, Vol. I. Genoa, 1861. Conf. 

 also Von Siebold, " Ueber die geschlechtliche Entwicklung d. Urodelen-Larven." 

 Zeit.f. wiss. Zool., Bd. xxvm., 1877. 



