Introduction 



portions of the austral zones, counting from north to south, 

 are known as the Alleghenian, Carolinian, and Austroriparian 

 faunas, respectively. In a consideration of the distribution of 

 the Salientia the first two may be taken together for the 

 sake of convenience and called the Eastern subregion. The dry 

 portions of the austral zones from the elevated plains to the 

 west coast are known as the Transition, Upper Sonoran, and Lower 

 Sonoran faunas. ' 



The Eastern subregion presents throughout similar con- 

 ditions of environment for the Salientia. Everywhere are fertile 

 fields or prairies, extensive wooded tracts, and a multitude of 

 lakes and ponds, rivers and brooks, all affording suitable haunts 

 and an abundance of insect food. Because of the thermal con- 

 ditions, there are more species near the southern limits, and 

 they diminish in number toward the north. This part of the 

 continent is the home of the genus Rana, possessing eight species. 



The species distributed throughout the extent of this sub- 

 region are as follows: Rana clamitans, Rana palustris, Rana pi- 

 piens, Rana sylvatica, Bufo americanus, Hyla versicolor, and 

 Hyla pickeringii. Species not found outside its boundaries are 

 Rana palustris, Rana sylvatica, Rana virgatipes, Bufo fowleri, and 

 Hyla evittata. Bufo fowleri is reported only from Massachusetts, 

 Rhode Island, and New York near the coast; Hyla evittata, Hyla 

 andersonii, and Rana virgatipes are found only in the country 

 east of the Alleghenies, New Jersey to Virginia. 2 A few species 

 found in a more or less limited section of this subregion are re- 

 ported from other subregions also; such are, Cboropbilus nigritus 

 triseriatus, Hyla andersonii, Acris gryllus, and Scaphiopus bol- 

 brookii. 



The boreal region has but few representatives of the Tailless 

 Batrachians. At the east it has Rana septentrionalis peculiar to 

 itself and gains Rana clamitans, Hyla pickeringii, Bufo ameri- 

 canus, and a few others from the austral zones just south. At 

 the west it has Rana cantabrigensis and its subspecies latiremis, 

 Bufo boreas, Bufo bemiophrys, and Choropbilus n. septentrionalis. 



The Austroriparian subregion consists of the southeastern 

 United States, i. e. the coast region south from isothermal 77 



!For boundaries of Mcrriam's Life Zones, see chart in Bulletin No. 10, U. S. Department of 

 Agriculture. 



2 The eastern part of the Carolinian division of Verrill or the Cisalleghenian division of Cope. 



38 



