_Lingua cordiformi; dentibus palatinis in lineâ transversâ interruptâ,
inter nares posteriores positis; tympano celato; dorso mammillato._
This curious species has, I believe, only once before been found. A
single specimen exists in the French Museum, which was brought from
Buenos Ayres by Mons. d’Orbigny, and which formed the subject of Mons.
Bibron’s description. Mr. Darwin’s specimen was taken on the open plains
at Monte Video.
Of the three species of this remarkable genus at present known, two are
inhabitants of Africa, from whence they were brought by Delalande. As
neither of them has as yet been figured, it was thought desirable that
the present opportunity should be taken to exhibit some of the generic
characters, and especially the hard horny spur on the hinder foot.
This genus is one of those bufonine forms of the RANIDÆ which
irresistibly lead us to doubt the correctness of the present received
arrangement of the anourous Amphibia.
GENUS—ALSODES. _Bell._.
_Caput convexum. Lingua anticè acutè-producta, posticè rotundata, et
libera. Dentes palatini inter nares posteriores. Tympanum celatum.
Aperturæ Eustachianæ haud conspicuæ. Digiti anteriores ad basin
tantùm—posteriores usque ad phalangem tertium membranâ connexi._
A genus of the Raniform group, nearly allied, as Mons. Bibron observes,
to _Scaphiopus_, by the structure of the hands, which, although without
any projecting rudimentary thumb, has a small process under the skin,
along the extreme margin of the first finger. In common with the genus
_Bombinator_, it has the opening of the Eustachian tubes so small as
scarcely to be detected.