_Capite brevi. Oculis subprominentibus. Tympano mediocri circulari.
Lingua subrotundâ, posticè libera, anticè angustatâ. Dentibus
palatinis in fasciculis binis, paulò separatis, ad marginem
postico-interiorem narium posteriorum. Dorso granuloso. Gulâ
plicatâ. Digitis anticis ad basin tantùm, posticis usque ad
phalanges penultimas palmatis. Suprà viridis, lineâ albâ laterali,
femoribus posticè atque lateribus abdominis, albis,
nigro-maculatis_.
Habitat, Maldonado, in grassy fields.
DESCRIPTION.—Head short, thick, the two sides of the muzzle
approaching each other at a rather acute angle, rounded at the
extremity. Eyes rather large and prominent. Tympanum circular, of
moderate size, and very distinct. Tongue entire, rounded, and free
behind, narrowed, and almost angular in front. Palatine teeth in
two oval parcels separated by a very small interval, and placed on
a line with the hinder margin of the _posterior nares_; the whole
of the back covered with extremely small granules; a slight fold
or elevation of the skin commencing above the posterior margin of
the tympanum, and extending backwards just above the arm, in front
of which it is met by a more considerable one which crosses the
throat from side to side; the under parts covered with large
granules; fore feet with the toes palmated only at the base;
hinder ones palmated to four-fifths of the length.
The colour of this beautiful species is thus given by Mr. Darwin:—“Above
emerald green, beneath white; a silvery white stripe bordered beneath
with a very narrow black line, extends from the corner of the eye, along
the side, to the thigh; a smaller one at the corner of the mouth; the
posterior surface of the hinder legs and the flanks marked with black
spots. Iris gold coloured; tympanum brown.”
DIMENSIONS.
Inches. Lines.
Length of the head and body 1 8
of the anterior extremities 1 0
of the posterior extremities 2 8
The young of this species, instead of the bright green colour of the
upper parts, is of a delicate grey with small brown markings; and a
lateral fascia of brown, bordered above and beneath with a white line,
extends from the fore part of the head backwards, the upper white line
nearly to the thigh, the inferior one to the shoulder. The black spots
on the flanks and thighs are but just visible.
This species so nearly resembles the _Hyla pulchella_ of Mons. Bibron,
at least as far as his description enables me to ascertain its
characters, that it was with some hesitation that I came to the
conclusion that they are distinct. Exclusive, however, of the difference
of colour, the back of the present species is granulated, and the throat
still more distinctly so, whereas the other animal has the skin on the
upper parts, as well as on the anterior part of the throat, quite
smooth. The palatine teeth also appear to be somewhat differently
arranged.
Mr. Darwin observes, that this species was found in numbers in the open
grass plains, and likewise in swamps, about Maldonado, and that they can
never ascend trees, as these are entirely wanting at the places
frequented by the Hylæ.
FAM.—BUFONIDÆ.
GENUS—RHINODERMA. _Bibr._
_Lingua cordato-ovata, posticè libera et subemarginata. Dentes
palatini nulli. Tympanum celatum. Glandæ parotideæ nullæ. Digiti
breves, depressi; anteriores ad basin tantùm, posteriores ferè
dimidio palmati. Rostrum cutis appendiculo filiformi instructum._