272 



FltOGS AND TOADS. 



ened and furnished with horny sheaths. In some of the genera, and especially the 

 one of which a representative is here figured, the mouth is extremely narrow ; 

 and although it is convenient to take this character as the basis of the name of the 

 family, it must not be considered that it is applicable to all its members. These 

 narrow-mouthed forms feed exclusively or mainly on ants and termites, and thus 

 exhibit a modification of structure approximating to that characteristic of ant- 

 eating mammals. More than half the members of the family are nocturnal, and 

 may be recognised by the vertical pupil of the eye. 



Short-Headed The exceeding plumpness of the body serves not only to dis- 



Frogs. tinguish the short-headed frogs (Breviceps) from all their allies, but 



also makes them some of the most peculiar of their class. Indeed, when the body 



EAST AFRICAN SHORT-HEADED FROGS (nat. size). 



is puffed out to its fullest extent, they more resemble indiarubber balls than frogs. 

 The genus belongs to a group in which the so-called precoracoid bones are present 

 and the metacoracoids much dilated ; and they are specially distinguished by the 

 horizontal portion of the pupil and the absence of teeth on the palate. Three 

 species are known, all of which are African, the one here figured (B. mossambicus) 

 inhabiting the eastern districts. Generally having a perfectly smooth skin, this 

 frog is of a brown or blackish hue on the upper-parts, with a dark oblique streak 

 below the eye. The narrow mouth and long tongue of this curious frog indicate 

 that its food consists of white ants. 



. , A frog (Rhinoderma darwini) belonging to the present family, 



and inhabiting Chili, alone represents a genus remarkable for the 



