360 BULLETIN 120, UNITED STATES NATIONAL MUSEUM. 



The DiscoGLOSsiDAE (fig. 223, p. 287). 



The Discoglossids have a peculiar, but not inexplicable, distribu- 

 tion. Ascaphus is found in extreme western North America. The 

 genera Alytes and Discoglossus are European. Bomhina is European 

 and eastern Asiatic. Stejneger (1905, a and 7;), who has studied the 

 distribution of this family, " makes the region southeast of the Hima- 

 layas, in Asia, the original home of the family. From here they 

 radiated to New Zealand in earW Cretaceous times,^^ to w^estern 

 America (over the land bridge that existed between Asia and North 

 America) in upper Cretaceous times, and to western Europe in early 

 Tertiary ^® times. Curiously enough, although at the moment of pub- 

 lication of his theory no Discoglossid toad had ever been found in the 

 region indicated as the center of radiation, a new species [Bomhina 

 maxima, Tong Chang Fu, Province of Yunan] was announced from 

 there one month later by Boulenger.^' 



The single specimen examined of the very local and rare Ascaphus 

 truei was barren. Alytes bears Cepedea minor. Bomhina carries 

 four species of Protoopalina of the archaic intestinalis group and 

 there is a single report of an infection by Opaline ranarum. No light 

 is cast upon the distribution of the Discoglossidae by our incomplete 

 infection data and we know no fossil forms, but the present occur- 

 rence of its members shows the family to have arisen probably from 

 forms in southeastern Asia during the Cretaceous (fig. 234), or later, 

 after Australia had severed its connection with Asia. Their spread 

 to Europe may have been either in the Cretaceous (fig. 234) or dur- 

 ing the Tertiary (figs. 236, 237). Their migration to extreme north- 

 western United States occurred probably in the late Cretaceous or 

 early Tertiary, as is indicated by the fact that they are known only 

 from the Olympic Mountains west of Puget Sound and from the 

 coastal Siskiyou Mountains. The American genus, Ascaphics, appar- 

 ently hadn't retained sufficient vigor for further spreading when in 

 the later Tertiary the Olympic Mountain region became connected 

 with lands further east.^^ They seem to be a waning family. 



'^ lAopelma, the only New Zealand amphibian, was classed as a Discoglossid at the 

 time Dr. Stejneger wrote this sentence. He wrote me recently that Liopelma has now 

 been found to be a Leptodactylid. 



» Arldt would date each of these migrations, except (lie one to America, one period 

 earlier, Australia severing its connection with Asia before the Cretaceous (fig. 234), and 

 Europe being separated from Asia in the early Tertiary by an ocean strait from the 

 Mediterranean Sea and the Indian Ocean, on the south, through the Caspian Sea to the 

 Arctic Ocean (fig. 236). 



"Quoted from Dickerson (1906), p. 52. 



" It hardly seems best to discuss here the question of late Cretaceous or nearly Tertiary 

 land connection from the Olympic Mountains eastward. It is simpler to align our data 

 with Arldt's charts as given. 



