MEXICAN TAILLESS AMPHIBIANS 201 



with R. palmipes. Central American and Mexican specimens now 

 referred to this species vsivy considerably in the extent of the web 

 between the toes, the texture of the skin between the dorso-lateral 

 glandular folds, the relative transverse diameter of the tympanum as 

 compared wdth that of the eye, the shape of the snout, and the general 

 coloration. Until the limits of variation with respect to characters 

 such as those just mentioned can be determined by aa examination of 

 adequate series from one or more localities in South and Central 

 America, respectively, it is impossible to arrive at any definite 

 conclusion. 



This frog is especially interesting because it is the only representa- 

 tive of the genus Rana in South America. Since its discovery by 

 Spix in stagnant water along the Amazon River in Brazil, its range has 

 been extended to western Brazil, to the Pacific coastal region of Ecua- 

 dor, and north as far as central Mexico. In spite of its rather exten- 

 sive range, comparatively little is known in regard to its habits and 

 structural variation. With one exception, all the specific names here- 

 inafter enumerated are based on young or immature individuals. 



Banula gollmerii, according to Boulenger, "was described from a 

 recently transformed young, from Caracas, measuring 50 mm. from 

 snout to vent." A somewhat larger frog from Caracas, which mea- 

 sured 63 mm. from snout to vent, became the type of Peters's Rana 

 affinis. The describer was inclined to regard the last-mentioned 

 species as a local variety of the European Rana temporaria. Peters 

 some years later allocated these two species to Rana palmipes. 



The types of Ranula brevipalmata and Ranula nigrilatus were col- 

 lected by Prof. James Orton at Nauta on the Maranon River in 

 northeastern Peru. Both of these specific names were based on 

 young frogs, and they have head-and-body lengths of 49 and 48 mm., 

 respectively. The toes of hrevipalmata are not fully webbed, since 

 the membrane reaches to the bases of the distal joints on all the 

 toes except the fourth, on which it extends to the penultimate joint. 

 The tympanum is described as being as large as the eye. The toes of 

 nigrilatus are fully webbed, and the tympanum is two-thirds as large 

 as the eye. 



The type of Rana vaillanti was collected by Firmin Bocourt on the 

 banks of MulHns River, near Belize in British Honduras. It is a 

 large adult, with a head-and-body length of 125 mm. The toes are 

 fully webbed, the vomerine teeth are in oblique groups at the level of 

 the posterior borders of the choanae, and the coloration of the under- 

 parts and limbs is similar to other Central American specimens of 

 Rana palmipes. 



Giinther seems to have overlooked the small terminal disks of the 

 toes when he described Rana bonaccana. Bonacca Island lies off the 

 coast of British Honduras and not off Yucatan as stated by Giinther. 

 It is the eastern one of a group known as the Bay Islands. No char- 



