308 GEOGRAPHICAL A>TD GEOLOGICAL DISTRIBUTION 



the Alps to a height of nearly 7,000 feet. Bufo calamita and B. 

 viridis are likewise distributed throughout the greater part of 

 Europe, the latter extending its range eastward to Turkestan. The 

 greater number of the American species occurring north of the 

 Mexican boundary belong to the Sonoran transition-tract, where 

 some six or seven species are met with. The common form of the 

 Eastern and Southern United States is the Carolina toad (Bufo 

 lentiginosus), of which several distinct varieties are recognised. A 

 number of bufonine species are found in the West Indies, and Bufo 

 (Chilophryne) dialophus is said to inhabit the Sandwich Islands. 



Next to the toads the most broadly distributed family is that 

 of the true frogs (Ranidse), which are most abundantly developed 

 in the Oriental and Ethiopian tracts, but are almost entirely absent 

 from Australia. Of some two hundred species (representing eighteen 

 genera), recognised as belonging to this group, somewhat more than 

 half belong to the genus Rana itself, whose distribution is practi- 

 cally that of the family. The genus is absent from the southern 

 parts of South America in the whole of which continent there 

 have been determined thus far only three or four species and from 

 New Zealand, but is represented by a single species (Rana Papua) 

 in North Australia. A solitary species (Rana Krefftii) is also found 

 in the Solomon Islands. The most broadly diffused Old World 

 form is the green or edible frog (Rana esculenta), whose habitat 

 extends from England and Scandinavia to North Africa, and east- 

 ward through Central Asia to China and Japan ; the species is 

 wanting in the island of Sardinia.* Somewhat less broadly dis- 

 tributed through Eurasia is the common frog (R. temporaria), which 

 is the most northerly of known species, ranging in Norway (var. 

 platyrhina) to beyond the seventieth parallel of latitude. In the 

 Alps it still frequents the waters at an elevation of 8,000 feet. 



The two commonest species of Eurasian frog have their American 

 representatives in the shad- or leopard-frog (R. halecina) and wood- 

 frog (R. sylvatica) the latter by some authors considered to be 

 identical with R. temporaria both of which are widely distributed 

 in the United States. The largest American species of the genus, 

 which alone represents the family north of the Mexican frontier, 



* Schrciber affirms that the species is also wanting in Great Britain ; but 

 the British Museum Is in possession of a specimen from Cambridgeshire 

 (Boulenger, " British Museum Catalogue," 1882). 



