Reasons for giving the name, &c. 213 
an animal, somewhere intermediate between fishes and lizards, 
although belonging to neither ; and the name Icthyo-saurus 
has been suggested by those who saw it in that point of 
view. 
Finding the farther I advanced in my investigation, that 
the approaches to the lizard were greater/and greater, and 
the only association with fishes was in the cupped vertebra, 
I was led to examine the vertebras of the Proteus, three 
1* 
specimens of which Sir Humphry Davy had just sent me 
from Germany, and found them all deeply cupped at both 
extremities, and the intervertebral cavity filled with a fluid. I 
found the same structure in the vertebrae of the syren from 
Carolina, and in those of the axolotl from Mexico, Dr. Leach 
having placed at my disposal a specimen of the axolotl, in all 
respects similar to that brought to Europe by Humboldt, and 
so well described by Cuvier. In both of these last species 
the cavity was filled with elastic ligament, and in the ax- 
olotl, the septum between the two cups was not completely 
closed. 
Mons. Cuvier, who has proved in so satisfactory a manner 
that the proteus and syren are completely formed animals, 
has expressed his doubts respecting the axolotl ; and 
hints at its resembling the larva of the salamander ; but 
leaves the matter open for future enquiry. 
When it is mentioned that the salamander has ball and 
socket joints to its vertebrae, and those of the axolotl are 
cupped, that celebrated anatomist will agree that these ani- 
mals belong to different genera ; and admit that, if the axolotl 
is a larva, the complete animal must have cupped vertebrae, 
which structure, I believe, is only met with in the proteus,, 
