THE OPALINID CILIATE INFUSORIANS. 343 



Sca-phiopus knowii to bear Cepedea, Protoopalina being the usual 

 Opalinid in this American genus, though one Zelleriella and two 

 Opalinae have been reported. We have no record of Scaphiopus in 

 South America or in Central America south of northern Mexico, 

 and northern Mexico zoogeographically belongs to North America 

 and not to tropical America. Scaphiopus alhus, or its ancestors, 

 probably, therefore, reached Key West from southwestern United 

 States by a route north of the Gulf of Mexico rather than by way 

 of tropical Central America and either of the land bridges from this 

 region to the West Indian lands and on to Florida. Probably, then, 

 its Cepedea is derived from some species in western North America. 

 If we are correct in regarding C. occidentalis and O. floridensis as 

 related to the southeastern Asian C. pulchra, then we must believe 

 that their forbears entered America from Asia by way of Alaska and 

 spread across temperate America to the tip of Florida, a migration 

 during the evolution of these species of Cepedea which almost rivals 

 that of the Hylas from tropical South America (their ancestral 

 home) north to Alaska and west to westernmost Europe. The 

 present distribution of the species of division 5 and comparison of the 

 charts would indicate origin in the Indian island in the later Cre- 

 taceous (figs. 235, 235, J.), or in the early Tertiary (fig. 236), or in 

 continental Asia or Malaysia in the late Tertiary (fig. 237) or later 

 (fig. 238), and spreading to their present homes — from Asia to 

 Malaysia or vice versa, to Japan, and by way of Alaska to North 

 America and Central America. 



Division 6 (fig. 253). 



C. hispanica (p. 161) in Rana Spain. 



C. cantabrigensis(p. 162).in Rana , Northwestern North 



America. 

 C. multiformis (p. 164) . . .in Hyla tropical Central America, 



Brazil. 



C. multiformis [of Polypedates schlegelii] (p. 165). in P. schlegelii (Raninae), 



Japan. 



C. seychellensis (p. 167)..in MagaUxalus (Raninae). Seychelles Islands. 



C. doliochosoma (p. 168) .in Bulo Tropical Central Americ a 



C. sp.P (p. 170) in Hyla Texas. 



C. longa (p. 168) in Rana "Asia," Japan, Formosa . 



C. opliis (p. 170) in Rana Formosa, East Indies. 



C. segmentata (p. 171). ..in Polyedates (Raninae) Cochin China, East Indies. 



In this division we place a group of species which, on the one hand, 

 approach the dimidiata group and, on the other hand, have a greatly 

 elongated body form, and, between, show a series of intergrading 

 species. Cepedea hispanica^ which most nearly approaches the 

 dimidiata group, is a southwestern European form, living in a region 

 now inhabited by two species of the dimidiata group. It may not 

 be closely related to the other species placed in this group, but seems 



