160 MR. TEGETMEIER ON SIREDON MEXICANUS. [ Mar. 24, 
situation so badly adapted for its structure and habits? But, in 
truth, natural selection has done absolutely nothing for our Wood- 
» pecker. Its colours are not dimmed, nor its loud notes subdued ; 
but even when it traverses the open country it calls about it the 
enemies from which it has little chance to escape. Natural selection 
has not endowed it, for its safety, with the instinct of concealment, 
so common in the true pampas birds. Its peculiar flight also, so 
admirably adapted for gliding through the forest, here only excites 
the rapacious birds to pursuit. In fact, the residence of this species 
in a region of which the conditions seem inimical to its preserva- 
tion, so far from modifying, seems rather to have intensified its cha- 
racteristics. Compared with the other Woodpeckers of this portion 
of South America, in structure, size, colour, voice, and flight, it is 
the type of the genus. The habit of occasionally perching on the 
ground it possesses in common with other species; but it never 
roosts on the ground, like the true pampas birds ; never builds a nest 
or burrows in banks, like the Patagonian Parrot; nor ventures on to 
those vast and treeless plains that border on its habitat. Scarcity 
of provisions and seeking for trees better adapted for breeding, with, 
perhaps, other reasons, have probably led to the distribution of this 
species over a great extent of country. 
“«« Twenty years ago, which is as far back as my recollection extends, 
the Carpintero was rather a common bird; but it has now become 
so very rare, that for the last four years I have met with only three 
individuals.” 

Mr. Tegetmeier exhibited living specimens of the Axolotl (Sire- 
don mexicanus), one of which (fig. 1, p. 161) had undergone the 
metamorphosis described by M. Aug. Duméril in the ‘Annales des 
Sciences Naturelles’ for 1867. 
This animal had hitherto been regarded as a perennibranchiate 
amphibian, as it breeds freely in the larval state, and in Mexico 
appears to be only known in that condition, although many natural- 
ists have suspected it to be the larva of a large Salamander. 
The specimens exhibited were hatched in the summer of 1868, 
and kept under similar conditions, without any change taking place 
beyond a steady increase of growth, during the succeeding winter and 
summer of 1869. Inthe autumn one only out of five began to change ; 
the external gills disappeared, the jaws became much more pointed, 
and the skin assunied a singularly mottled appearance. The animal 
did not leave the water, but, when the temperature was warm, usually 
breathed by standing erect against the side of the aquarium and 
elevating the nostrils above the surface, respiration being effected 
by the very rapid movement of the skin of the lower jaw. During 
cold weather it usually remained submerged, rising at intervals to 
the surface to breathe. 
Mr. Tegetmeier also exhibited some microscopic slides, on which 
were mounted portions of the excessively thin cuticle of the feet of 
the animals, that had been shed like a glove, the skin of the toes 
being partly inverted, 
