A REMARKABLE AXOLOTL FROM NORTH 
DAKOTA. 
HENRY LESLIE OSBORN. 
THE name “axolotl” is primarily the popular designationamong 
the Mexicans for an animal found abundantly in their lakes. 
The name “siredon ” has also been applied to this and allied 
animals, at first as a generic name, till that was shown to be 
superfluous by the demonstration of the amblystomid nature of 
the axolotl, or siredon, larva. The Mexican axolotl is said not 
to metamorphose from an aquatic to a terrestrial form after 
the manner of Amblystoma, but to be a permanently aquatic 
animal, thus imitating Necturus physiologically, with which, 
however, it has no morphological relationship, as indicated by 
the fact that Necturus has no free gula folds or opercula, only 
two gill slits, no dorsal fin, a much shorter tail, and only four 
toes in the hind limb. It had early been strongly surmised 
that the axolotls were amblystomas, but Dumeril of Paris in 
1865 was the first to observe the metamorphosis of axolotls into 
true adult amblystomas. Specimens in the Jardin des Plantes 
laid eggs which in developing did not stop when they reached 
the form of their axolotl parents, but continued to develop, 
losing the gills and many other larval features and becoming 
true terrestrial salamanders. Dumeril’s observations were 
corroborated by Marsh in 1868, by Tegetmeyer in London in 
1870, and by Madame Chauvin in 1874. The latter managed 
to arrange an experiment in which young tadpole larvae were 
gradually transferred from an aquatic to a terrestrial environ- 
ment, resulting in the correlated metamorphosis to the terres- 
trial form. 
While Dumeril, Tegetmeyer, Marsh, and Chauvin have 
shown that an amphibian with the characters of the Mexican 
axolotl does metamorphose into a salamander under some con- 
ditions, it has not been satisfactorily shown as yet that the 
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