OPALINID CILIATE INFUSORIANS — METCALF 591 



Hylidae: America, Australasia, except New Zealand, one species (with several 

 subspecies) in Europe and eastern Asia. Prntoopalina, Zelleriella, Cepe- 

 dea, Opalinae angustae. 

 Leptodactylidae; Tropical America, Australasia (except New Zealand) , Africa (?). 



Protoopalina, Cepedea, and especially Zelleriella. 

 Gastrophkynidae: Neotropics, Ethiopia, Madagascar, southern India, south- 

 eastern Asia, Amboina, Papua. Protoopalina, Zelleriella. Opalina, and 

 especially Cepedea. 

 Ranidae: 



Ceratobairachinae, Solomon Islands. Opalinids unknown. 

 Raninae, Eastern Hemisphere (except Australia, Tasmania, and New 

 Zealand), North and Central America, one species each in the northernmost 

 portions of Australia and South America, respectively. Protoopalina, 

 Zelleriella (4 cases), and especially the multinucleate genera Cepedea and 

 Opalina. 

 Dendrobatinae, Neotropics. Zelleriella. 

 Mantellinae, Madagascar. Opalinae latae. 

 Cardioglossa, classification doubtful, western Africa. Opalinids not studied, 



The Opalinidae arose as Protoopalinae of subgenus I in archaic 

 Anura, perhaps Pipidae, apparently in the Southern Hemisphere, and 

 spread to all portions of the earth capable of supporting Anura, 

 except possibly Lemuria where their present absence is unexplained. 

 As the Anura evolved into their several families, their commensal 

 opalinids evolved to their present diversity. The interrelationships 

 and the course of the evolution of the families, subfamilies, genera, 

 and species of the Anura are by no means understood, though some 

 things are indicated. (Fig. 147.) 



THE PIPIDAE (Fig. 148) 



The Pipidae seem the most archaic of extant Anura, the African 

 and South American genera having diverged to different subfamiUes. 

 The Papinae (Guianas) have not been found carrying opaUnids, 

 probably because of the absence of free-living, browsing, vegetarian, 

 aquatic larvae, for it is in this stage of its Ufe history that an anuran 

 becomes infected with encysted opaUnids from the recta of the hosts. 

 The Xenopodinae (Africa) bear Protoopalinas belonging to the most 

 ancient subgeneric group, I. It seems natural that the most archaic 

 family of Anura should bear the most archaic opaUnids, members of 

 the most archaic subgenus of the most ancient genus. 



THE DISCOGLOSSIDAE, OR BELL TOADS 



The Discoglossidae, which, according to Stejneger, probably arose 

 in southeastern Asia, near the eastern end of the Himalayan highlands, 

 spread in three directions: (1) The Discoglossinae spread northward, 

 inhabiting western Europe and northern Africa (Bombma, Disco- 

 glossus, Alytes) and also eastern Asia (Bombina). This was one 

 migration, by routes north of the Himalayas, the eastern and western 

 genera becoming separated by the development of desert conditions 



