THE OPALINJD CILIATE ] XFUSORIAXS. 317 



tions need scrutiny. The presence in a Urodele, Triturus^ is very 

 unusual and may well be due to this newt's habit of devouring 

 Anuran tadpoles. The infrequent occurrence in European frogs 

 and toads may be due to temporary cross infections of these hosts 

 by cysts of unaccustomed parasites, like many of the author's arti- 

 ficial cross infections of Anura with unusual species of Opalinids 

 (Metcalf, 1909). The records from two Australian Hylas and an 

 Australian Leptodactjdid may very likely be based upon infection 

 by similar but not identical species of Protoopalina, but they indi- 

 cate, at any rate, the presence in Australia of one or more species of 

 this group besides P. hylarum. The species of this group do not 

 show the two forms, very stocky and A'ery slender, nor do they have 

 posteriorly either a sharp point or any protuberance such as that 

 which gave the specific name to P. caudata. Some individuals of P. 

 caudata are very similar in shape to ordinary P. intestinalis, but the 

 species as a whole is quite different. Europe and Australia are the 

 homes of the species of this group, a distribution which again argues 

 that the group is an old one, having arisen in southeastern Asia, 

 Malaysia, or Australasia at the time when Australia was connected 

 with continental Asia, that is, in Jurassic times. (Figs. 232, 233, 

 234.) They were Jurassic in origin, rather than Triassic (fig. 232), 

 for none of this group are known from Africa or South America. 

 Members of this group may very likely be discovered in Asia after 

 more thorough exploration of Asiatic Discoglossids and Pelobatids. 

 In the absence of data from southern Asia, the available evidence 

 indicates that the representatives of this group passed from Aus- 

 tralia to Europe by a route north of the Himalaya ISIountains. and 

 the absence of this group from tropical Africa, so far as known, 

 emphasizes the indication that the distribution was northern and not 

 equatorial. It is to be regretted that our data from southern Asia 

 are so scant. 



Group 5 (fig. 243). 



P. moatana p. 54 1 in Pelobatidae Java. 



P. adelaidensis (p. 53 1 in Hyla Australia. 



These two species ajjproaoh group 4, but have quite diflerent pro- 

 jiortions. Their occurrence on both sides of the Bali-Lombolc line 

 is an indication of pre-Eocene origin (fig. 236). 



The presence of members of this group in Australia and Java, 

 but not in Sumatra and Asia, is in agreement with Arldt's (1907) 

 conclusion that Java remained longer in connection with Australia 

 than did Sumatra. The conditions seem to indicate origin in Aus- 

 tralasia (including JaA-a) during the Cretaceous (fig. 234). The ab- 

 sence of this group from Soutli America perhaps deserves notice, 



