SUBORDER B 



DUPLICIDENTATA 



115 



Family 1. Leporidae. Rabbits and Hares. 



-f P. |- M. P'^ peg-like, the remaining P resembling the molars. Skull 

 laterally compressed, clavicle incomplete. Hind legs and ears long, tail very short. 



Palaeolagus Leidy. White River Oligocene ; North America. 



Panolax Cope. Miocene ; North America. 



Lepus Linn. In North America extending from the John Day Miocene 

 to the present day. In Europe and Asia from the Lower Pliocene to 

 recent times. 



3-2 



P. 



2-3 

 233'- 



Family 2. Ochotonidae {Lagomyidae). 



Only P ^ resembles M. Skidl low. Clavicle complete. Hind 

 legs and ears short. Tail lacking. 



In Europe extending from the Upper Oligocene to the modern fauna. 

 Recent in the eastern part of Europe, in the 

 mountain regions of Asia and North America. 

 Fossil also in the latter continent. 



Prolagus Pomel {Myolagus Hensel) (Fig. 147). 



3.2. 



From Miocene to the Pleistocene of Europe. 



3.2. 



2.2. 



Titanomys v. Meyer 



and Miocene. 

 Dep6ret. 



Lagopsis Schlosser 



Upper Oligocene 

 T. visenoviensis v. Meyer, T. fontannesi 



3.2. 



2^3^ 



Miocene. 



mZ 



Fig. 147. 



Ochotona Linck (Laqomys CuV.). Recent in the Prolagus oeningensis Konig. 



■, • T c .^ ■ 1 r^T 1 Upper Miocene of La Gnve St. 



northern hemisphere, fossil in the Pliocene and Aiban. a, upper molars, b, 



Pleistocene of Europe and North America. M*ajw\)"° ^^^' ^^'^ ^^"^^ 



Geological Distribution of the Rodents. 



The oldest known rodent is that from the Lower Eocene of North America 

 (Wasatch and Bridger beds), and belongs to the genus Paramys, one of the 

 Ischyromyinae. Accompanying this form in the Uinta beds is found Protoptychus, 

 ancestor of the recent subfamily Geomyinae, which is now restricted to North 

 America. The Paramyinae give rise in North America to the Sciurinae and 

 Haplodontinae, the former later becoming widely distributed in Europe. The 

 Ischyromyinae become extinct in the White River Oligocene, where the forms 

 Leporidae, Castorinae and Cricetinae first appear. The Castorinae are repre- 

 sented in Europe at an early period, whereas the Cricetinae are apparently 

 of Old AVorld origin, and the Leporidae first appear in Asia and Europe in 

 the Pliocene. Recent North American rodents are essentially the same as 

 those of Eurasia. The Arvicolinae and Ochotonidae from the Pleistocene of 

 Europe, and the Erethizontinae, originating in South America, are successors 

 of families already found in the Tertiary. 



In the Eocene of Europe, and more especially in the early Oligocene of 

 the same region, rodents display a great diversity of forms. Besides the 



