118 THE WANDERINGS OF ANIMALS [CH. 



undoubtedly indicate land connexion of North and 

 South America during at least part of the Cretaceous 

 epoch, and a longer intercourse bet ween North America 

 and Europe. 



2. Archaic Metatheria of Jurassic date, some of 

 which are supposed to be ancestral to the Insectivora, 

 e.g. Triconodon,Amphitherium, Dryolestes of England 

 and North America, 



3. Archaic or ancestral marsupials. 



(a) Polyprotodonta, with a complete set of four 

 pairs of lower incisors, e.g. Pediomys and Didel- 

 phops of North American Upper Cretaceous. Bor- 

 hyaena from South America, Eocene to Miocene, 

 supposed to be nearly allied to the Australian 

 Thylacinus. Paratherium from Lower Eocene into 

 Oligocene in North America where it died out, 

 but continued in Europe from Upper Eocene into 

 Lower Miocene, indistinguishable from the recent 

 Didelphys, which is also known from South Ameri- 

 can Pleistocene, whence one species, the common 

 opossum, D. virginiana, now extends far into the 

 United States. 



(b) Diprotodonta. Many species of Epanorthus 

 and Abderites in Patagonian Tertiary, considered as 

 allies of the recent Colombian Caenolestes. Their 

 diprotodont feature may be a case of parallelism with 

 the Australians, but it is significant that the recently 

 discovered Wynardia bassiana, described by Spencer 



