1 66 AMPHIBIA 



in former times by the monks of Lombardy. The edible frog 

 croaks much more than the common species ; the latter only does 

 so individually and occasionally, but edible frogs are gregarious 

 and they croak in concert, often the whole night long. 



R. catesbiana, formerly known as R. mugiens, is the bull- 

 frog of North America ; it reaches a length of five to seven 

 inches with hind-legs nine or ten inches long. (Plate XIV., C.) 

 The tympanum in this species is very large and the voice loud 

 enough, when uttered by hundreds of males in a pond, to be 

 heard half a mile off. 



Sub-Order Arcifera 



Fam. BUFONIDAE. — In this family there are no teeth in 

 either jaw, no ribs, and the transverse processes of the sacral 

 vertebrae are dilated. The genus Bitfo, like Rana, is large, con- 

 taining more than a hundred species which are distributed all 

 over the world except Australasia and Madagascar. The 

 tongue is free behind but not bifurcate ; the toes of the fore-foot 

 are free, those of the hind-foot more or less webbed. The skin 

 always contains numerous poison glands which are concentrated 

 in thickened swellings behind the ear. The rough warty char- 

 acter of the skin in the common species is not universal, in some 

 it is smooth and moist, in others again covered with dry, horny 

 spikes. The common toad, B. vulgaris, has a warty skin and 

 sometimes minute cornified spines also. (Plate XV., C.) The 

 female is from three and a half to five and a quarter inches in 

 length, the male somewhat smaller. The male has no vocal sacs 

 and has slighter nuptial excrescences than the frog ; they breed 

 like the frog in the water and the eggs are distinguished by 

 forming strings instead of irregular masses. 



The Natterjack toad, Bufo calamita, occurs in Ireland where 

 the common toad is absent. 



The sub-order includes four other families, namely Pelo- 

 batidae, burrowing toads, Discoglossidae with tongue attached 

 by its whole base, Hylidae, the tree-frogs, and Cystignathidae. 



Sub-Order Aglossa 



This sub-order is not divided by Dr. Gadow into families. 

 The tongue is absent, the Eustachian tubes, conducting air from 

 the mouth to the middle ear, open by a single aperture in the 



