The Transformation of the Mexican Axolotl. 577 



ever, less concave in Amblystoma than in Siredon 

 (Dumeril). 



I have not yet been able to verify Dume'riPs 7th 

 and 9th statements, as I did not want to kill any 

 of my living Amblystomas, 16 simply in order to 

 confirm the observations of a naturalist in whom 

 one may certainly place complete confidence. 

 Neither have I as yet observed the transformation 

 of the branchial arches, but all the other state- 

 ments of Kolliker and Dume'ril I can entirely cor- 

 roborate. 



The structural differences between Axolotl and 

 Amblystoma are considerably greater and of more 

 importance than those between allied genera, or 

 indeed than between the families of the Urodela. 

 The genus Siredon undoubtedly belongs to a 

 different sub-order to the genus Amblystoma into 

 which it occasionally becomes transformed. 

 Strauch, the most recent systematic worker at 

 this group, distinguishes the sub-order Salaman- 

 drida from that of the Ichthyodea by the posses- 

 sion of eyelids, and by the situation of the pala- 

 tine teeth in single rows on the posterior edge of 

 the palatal bone : in Ichthyodea the eyelids are 

 wanting and the palatine teeth are either " situated 

 on the anterior edge of the palatal bone," or 



" [Eng. ed. These Amblystomas have since died and 

 have been minutely described by Dr. Wiedersheim. See his 

 memoir, " Zur Anatomic des Amblystoma Weismanni" in Zeit. 

 fiir wiss. Zool., vol. xxxii. p. 216.] 



