312 BULLETIN 120, UNITED STATES NATIONAL MUSEUM. 



apparently older than the time when Australasia separated from 

 continental Asia. It seems then pre-Cretaceous at least (figs. 233, 

 234) . Its presence in Australasia, Africa, and South America would 

 seemingly place its origin still a period earlier, indicating its pres- 

 ence as early as the Triassic in Equatoria (fig. 232), the continent 

 including Australia, Africa, and South America. For further dis- 

 cussion see page 325. 



There are indicated different degrees of relationship between the 

 species of the genus Protoopalina^ allowing us to arrange them in 

 several subgeneric groups. ^^ 



Group I (fig. 240, dots). 



P. diplocarya (p. 33) in Eleutherodactylus (Leptodactylidae) 



Patagonia. 



P. papuensis (p. 34) in Hyla Papua. 



P. acuta (p. 36) in Limnodynastes (Leptodactylidae) Australia. 



P. xenopodos (p. 61) in Xenopus (Pipidae) Tropical Africa. 



All four species have the body drawn out posteriorly into a long, 

 slender, unciliated point. These slender, tapering Protoopalinas 

 have much the same form as the microgamete mother-cells of differ- 

 ent species of Protoopalina, Gepedea, and Opalina and are similar in 

 shape to the young individuals of a number of species of Cepedea, as, 

 for instance, C. dimidiata. They are probably the most archaic group 

 of species in the genus, though there is not definite evidence absolutely 

 to demonstrate this. They may at least be accepted as among the 

 most archaic species. The Australian and Papuan species are very 

 similar to each other; so also are the Patagonian and African species. 

 The geologic distribution of these four species, two in Australia, 

 one in South America and one in tropical Africa, indicates a south- 

 ern origin and reinforces evidence from other sources of former 

 land connection between Australia, South America, and tropical 

 Africa. Comparison with the charts (figs. 232 to 238) indicates 

 origin in the equatorian continent during the Triassic or earlier. 

 The earliest known fossil Anura are an ^^ Oxyglossus''''^^ {Ranlnae) 

 from the Eocene (Gadow, 1909) or Comanchian (Schuchert, 1915 ?) 

 of Wyoming, Bufo serratus from the Oligocene of Europe (Gadow, 

 1909), B. gessTieri from European Miocene rocks (Gadow, 1909), 

 and Palaeohatrachus (Pipidae) from the mid-Tertiary of Europe 

 (GadoAV, 1909). The geographic distribution of the characteristic 

 parasites of the Anura apparently places the origin of the hosts 

 at least two geologic periods earlier than their earliest known fossils. 

 The paleontologic data are strangely scant for the Anura. The 



^ All the subgeneric groups in the genera Protoopalina, Cepcdca, and Opalina were 

 demarcated before the author began the review Of the geographical distribution and have 

 not been modified in connection with this review. They therefore are based upon morpho 

 logical data ratlior than upon distribution. 

 ^ Identification very doubtful. 



