1905.] AMPHIBIANS AND REPTILES, 205 



matinse point to the long-continued land-connection with Eastern 

 Asia, A later centre of dispersal lies in the Eastern lialf 

 of North America, the old Appalachia, the Alleghany moun- 

 tains, &c., whence Urodeles have spread, as Plethodontinse and 

 Desmognathina3, over most of the Eastern and Southern States, 

 also into and through Mexico's eastern half. This spreading 

 dates back to Miocene times, witness the existence of Spelerpes in 

 Hayti, while others have reached even South America, and, lastly, 

 the occurrence of a Pletliodon somewhere in the La Plata basin. 

 Much later immigrants, directly from the old north-western home, 

 are Amhlystoma and Bairachoseps : A. tigrinum and B, aitemiaitts 

 being identical species in the States and in Mexico, only A. alta- 

 mirani being a new modification ; while ^peleri^es has developed 

 many species, different in the north, centre, south, and in Hayti. 



Anura. 



Pelobatid^,- — Sccq^hiopus, the Spadefoot, closely allied to the 

 European Pelohates, is the only American genus of this family, 

 with about 7 or 8 species, two of which are restricted to the United 

 States. The zone of sandy terrain of Texas, Xew Mexico, and 

 California is richest in Spadefeet, whence they have extended over 

 the Mexican plateau down to the Pacific and Atlantic coasts, 

 S. clugesi s. hammondi has the widest distribution : fi-om Missouri 

 and California through New Mexico and Texas, the mountains 

 west of Chihuahua, in Guanajuato, and again on the southern slope 

 of Oaxaca, where I found it at Totolapan, its most southei-n locality. 

 The retiring habits of the Spadefoot no doubt account for the 

 few scattered records. The well- wooded mountain ranges which 

 form the south-eastern, southern, and western borders of the 

 Mexican plateau are a natural obstacle to a further southward 

 spreading of this genus. 



BuroNiD^. — Central America and Mexico are one of the centres 

 of Bufonidpe. Concerning Mexicans, they can be grouped as 

 follows : — 



1. Indigenous: Rhinoj^hryne dorsalis, the only species of the 

 genus, a toad specialised as an eater of Termites ; it is restiicted to 

 the moist Atlantic Tieriu Caliente, from Tuxpan, noith of Yera 

 Cruz, through the Isthmus to Campeche and Guatemala, The 

 light-coloured spots on the bluish-slaty black skin are either yellow 

 or orange to red, varying in individuals from the same locality. 

 They are very sluggish, rather nocturnal, and retire beneath a 

 rotten stump or into a small self-dug hole in the moist humus, 

 Aztec name " Poche." 



2. Southerners : Ungi/stomojys, the few species of which range 

 from Venezuela and Ecuador northwards, but only E. 2'>ustulosus 

 reaches the Isthmus of Tehuantepec, 



Several of the 13 species of Bufo found in Mexico are southern 

 forms : in their spread northwards they either stop short at the 



