442 



AMPHIBIA— ORDER I.—ECAUDATA. 



a verj- large number of species distributed over the greater part of the world 

 with the exception of Oceania, Australasia, and Madagascar. In this genus 

 the'pupil of the eye forms a horizontal slit, the tip of the tongue is not 

 notched, the toes of the fore-feet are free, but the hinder ones are partially 

 webbed. Occasionally the ends of the toes are expanded into small discs ; 

 the head may bear bouy ridges, and in maay cases the skin is covered with 

 warts, which uiider excitement secrete a milky acrid fluid. Two species are 



met with in Britain, namely the 



Fiq. 6.— Natteejack Toad {Bu/o calo.mHa) 



common toad (^B. vulgaris), and the 

 natterjack {B. calamita); the latter 

 being very local in our islands, 

 and easily recognised by the 

 whitish or yellow streak on the 

 middle of the back. Although 

 not found in Britain, a third 

 European species is the handsome 

 green toad {B. viridis), which also 

 ranges into the north of Africa 

 and Asia. The males differ from 

 those of the common species in 

 possessing a vocal sac beneath the 

 throat. 



Although many of the tree-frogs belonging to this family are very similar 

 externally to the Dendrohatida, they agree with the toads in the conforma- 

 tion of the skeleton of the chest. From the Bufonidce they 

 Family HyHdm. may be readily distinguished by the possession of upper 

 teeth ; while a still more distinctive peculiarity is to be 

 found in the claw-shaped terminal joints of the toes. The frogs of this 

 family, which are mostly arboreal in their habits, and are ranged under a 

 considerable number of generic divisions, attain their maximum development 

 in America (especially its tropical regions) and Australasia, but also occur in 

 Europe and Northern Asia, while a single representative of the typical genus 

 Hyla is found in India. The genus 

 just named includes more than a 

 hundred and fifty species, and has 

 a distribution coextensive with 

 that of the family. Whereas the 

 European U. arborea is a tiny little 

 creature, some of the Brazilian 

 species measure as much as three 

 inches in length. These frogs have 

 the tips of the toes expanded into 

 discs, and the hind-feet more or 

 less fully webbed. In the eye the 

 pupil is horizontal ; and the hinder 

 end of the tongue may be either 

 adherent or partially free. The 

 males of the European species, and 

 likewise those of some other kinds, 

 have a huge vocal sac on the throat. 

 In order to assimilate them to their surroundings, tree-frogs are of a brilliant 

 green colour. Except during the breeding season — when they descend tem- 



Fig 7.— European Tbee-Fkoq (ffj/I^artorco). 



