REPTILES. 41 



by Mons. d'Orbigny, and which formed the subject of Mons. Bibron's descrip- 

 tion. 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 oppor- 

 tunity 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 RanidjE which irresistibly 

 lead us to doubt the correctness of the present received arrangement of the anou- 

 rous Amphibia. 



Genus— ALSODES. Bell. 



Caput convexum. Lingua antice acutb-producta, postice rotundata, et libera. Dentes 

 palatini inter nares posteriores. Tympanum celatum. Aperturse Eustachianse 

 haud conspicuce. Digiti anteriores ad basin tantum — posteriores usque ad pha- 

 langem tertium membrand 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 mar- 

 gin 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. 



Alsodes monticola. Mihi. 



Plate XVIII.— Fig. 3. 



Description. — Head semi-elliptical, somewhat convex, with the muzzle nearly perpendicular; 

 vertex smooth. Eyes of moderate size. Nostrils very small, opening upwards. Tongue 

 broad and rounded behind, narrowing to a point at the apex, detached at the posterior part. 

 Palatine teeth in two small approximate patches, between the posterior nostrils. Openings of 

 the Eustachian tubes scarcely visible. Extremities of moderate length. The fore feet, with 

 four rather short toes, connected at the base by a short membrane ; the inner toe broad, and 

 with a slight projection under the skin, along its inner margin; hinder toes connected as far as 

 the joint of the second and third phalanges. 



The colour of the only specimen in the collection has become totally changed 

 into a smoky brown by the spirit, but the following is Mr. Darwin's description 



G 



