Tlie Transformation of the Mexican Axolotl. 575 



an explanation of the complete transformation of 

 the whole structure, such as I have already alluded 

 to, and which I will now enter into more closely. 



The differences between the Paris Axolotl and 

 its Amblystoma according to Dume*ril, Kolliker, 

 and my own observations are as follow : 



1. The gills disappear; the gill-clefts close up, 

 and of the branchial arches only the foremost re- 

 main, the posterior ones disappearing. At the 

 same time the os hyoideum becomes changed 

 (Dumeril). 



2. The dorsal crest completely disappears 

 (Dumeril). 



3. The aquatic tail becomes transformed into 

 one like that of the salamanders (Dumeril), which, 

 however, is not as in the salamander cylindrical, 

 but somewhat compressed laterally (Weismann). 



4. The skin becomes yellowish white, irregu- 

 larly spotted on the sides and back (DumeYil), 

 whilst at the same time its former grey-black 

 ground-colour changes into a shining greenish 

 black (Weismann) ; it loses, moreover, the slimy 

 secretion of the skin, and the cutaneous glands 

 become insignificant (Kolliker). 



5. The eyes become prominent and the pupils 

 narrow (Kolliker), and eye-lids capable of com- 

 pletely covering the eyes are formed ; in Axolotl 

 only a narrow annular fold surrounds the eyes, so 

 that these cannot be closed (Weismann). 



6. The toes become narrowed and lose their 



