New Species of Bairacian Reptiles. 57 
donc, si l’on vent, porter le nom d’amphibies dans son ac- 
ceptation la plus rigoureuse.’’? (Cuvier Anim. douteux, Voy. 
d’Humboldt.) 
In specimens which we subjected to examination, we found 
the lungs and nostrils to exist in a rudimentary state; the lat- 
ter are small, and barely admit the passage of a very fine 
bristle; the former are of a deep black colour. That the 
larve do not depend altogether upon their branchia for the 
decarbonization of the blood, we were satisfied, by observing 
them to rise frequently to the surface of the water, in order to 
discharge the foul air and to respire: this process was re- 
peated every three or four minutes, on some occasions, in a 
number of these animals confined in a tub of water.—Accord- 
ing to Swammerdam and Roésal, the branchia of tadpoles are 
exterior and free during the first days of theirexistence. This: 
statement was not verified by observations we have made on 
very young tadpoles of this country, in which not the slightest 
vestiges of branchia or of feetare visible. We subjected a num- 
ber of individuals to examination, both with and without the 
glass: the subjects appeared to have just emerged from the eggs, 
were nearly transparent, the viscera being apparent through 
the abdominal parietes; though it is not improbable that these 
organs may have existed at a still earlier period. The frog,, 
in common with other batracians, being destitute of true ribs 
and a diaphragm, is obliged to force the air into the lungs by: 
means of the muscles of the throat; this is effected by closing 
the lips, and forming a vacuum by protruding the muscles of 
the throat, when the air rushes into the nostrils, which open 
in the anterior. portion of the palate, generally between two 
transverse palatine ridges. I could observe no valves at these,’ 
openings, which, we are informed by several authors, exist 
there, for the purpose of preventing the escape of the air; and 
have little doubt but that the fleshy and free extremity of the 
tongue, by being applied to the palate of the mouth, performs 
the function of a valve. In addition to the ordinary perma- 
nent specific distinctions, I have observed good characters in 
the form, number, and size of the transverse palatine plates. 
Some species of frogs possess, to a remarkable degree, the 
faculty, more or less peculiar to all the batracian order, of 
changing their colours. The Rana pipiens, or common bull- 
frog, | have observed to change, in the course of a few hours, 
from a light ash, or nearly dirty white colour, to a light green 
Vou. X.-—No. 1. g 
