THE OPALINID CILIATE INFUSORIANS. 376 



have sent a few migrant species into western North America, and the 

 narrow Opalinae, Western Hemisphere forms, have sent one repre- 

 sentative into Euro-Asia since the early Pliocene, but while the 

 broad Opalinae have entered equatorial Africa, neither broad nor 

 narrow Opalinae have passed from North America into South 

 America. Each of the four genera thrive under widely diverse con- 

 ditions of temperature. 



Noting the indications as to the Opalinid and Anuran fauna of 

 the three great land zones, Antarctic, equatorial, and northern, we 

 may say: I, 1, In Equatoria arose; «, the earliest Opalinidae, Pro- 

 toopdHnae^ not later than Triassic times, and in Anura probably more 

 primitive than any now persisting; 5, the Discoglossidae ; c, the 

 Bufonidae, excluding the genus Bufo; 2, In Australasia, after it 

 separated from Equatoria, or in southeastern Asia-Malaysia with 

 which Australia promptly united, arose groups 2, 3, 4, 5, and 6 of the 

 genus Protoopalina and also the Pelobatidae; 3, In South Atlantis 

 (South America-Africa and its Madagascar-India extension, the 

 Jurassic and early Cretaceous continent formed from western 

 Equatoria) arose groups 7 and 9 of the genus Protoopalina, the 

 genus Cepedea and its divisions 4, 6, and perhaps 5, also the Gas- 

 trophrynidae, the Raninae and the Dendrohatinae; 4, in the Brazilian 

 highlands the Hylidae evolved during the early Cretaceous; II, In 

 Antarctica and connected South American lands arose Zelleriella 

 and the Leptodactylidae ; III, In Arctogea arose a, group 8, of the 

 genus Protoopalina; h, division 2, and perhaps also division 5 of the 

 genus Cepedea; c, Opalina and both its subgeneric groups Opalinae 

 latae and Opalinae angustae; d^ the genus Ascaphus among the Dis- 

 coglossidae ; e, the genus Scaphiopus among the Pelobatidae ; /, the 

 genus Acris and possibl}'^ the genus Chrophilus among the Hylidae, 

 although the latter genus is known also from northwestern South 

 America. 



Anura arising in the western end of the continent Equatoria show 

 remarkable migrations: 1, the Hylidae evolved in the Brazilian 

 highlands during the isolation of this region in the early Cretaceous 

 and, as new connections were established, they spread first to 

 Australia and later throughout tropical America and all Arctogea ; 

 2, the Leptodactylidae evolved in Argentina-Patagonia-Chile dur- 

 ing the Cretaceous or early Tertiary separation of this land mass 

 from both tropical America and Africa, and later spread by way of 

 Antarctica to Australia and New Zealand, probably during the early 

 or middle Tertiary. There have thus been in the western hemisphere 

 northward migrations from Equatoria to Arctogea and southward 

 migrations from Equatoria to Antarctica. In the eastern hemisphere 

 there was Jurassic migration of Equatorian Anura from Australia to 



