114 THE NEOG^IC REALM. [CHAP. 



2. PERISSODACTYLA. 



Tapiridae. Elsewhere only in Malaysia at the 

 present day, but formerly widely distributed 

 over the northern hemisphere. 



Equidae. Now unknown, except through intro- 

 duction. In addition to the cosmopolitan 

 Equus (including Tertiary forms), the pecu- 

 liar Pampean genera * Hippidium and * Ono- 

 hippidium. 



3. * Litopterna. Santa Cruz. 



* Macraucheniidce. Santa Cruz. 



* Proter other iidtz. Santa Cruz. 



4. * Astrapotheria. Santa Cruz. 



* A strapotheriidce. Santa Cruz. 



* Homalodontotheriida. Santa Cruz. 



5. * Toxodontia. Santa Cruz. 



* Toxodontidce. Santa Cruz. 



* Typotheriida. Santa Cruz. 



* Pachyruchidce. Santa Cruz. 



6. * Pyrotheria. Patagonian beds lying below those of 



Santa Cruz. 



* Pyrotheriidte. Patagonian beds. 



7. PROBOSCIDEA. 



Elephantidse. Represented by Mastodon in 

 the Pampean and Monte Hermoso beds. 



VI. RODENTIA. 



I. SCIUROMORPHA. 



Sciuridae. Represented by Sciurus as far south 

 as Paraguay. 



* Castoroididse. Peculiar to New World. 



2 MYOMORPHA. 



Muridae. Represented by species of the New 

 World genus Sitomys, as well as by several 

 peculiar types such as Rhithrodon, Ichthyomys 

 of Peru, Holochilus of Brazil, etc. 



