VEETEBKATA 



113 



Sciuromorpha only occur fossil in the Northern Hemi: 



sphere, and are the prin- 

 cipal Glires of the Eo- 

 cene. From that peri- 

 od they became more 

 abundant in both North 

 America and Europe, 

 reaching their highest 

 expression in thebeaver, 

 and spread into South 

 America. (Figs. 48-49.) 

 The M y o m o r ph a 

 (mice, rats, etc.) have a 

 few supposed represen- 

 tatives in the Eocene of 

 Patagonia, but only cer- 

 tainly begin in the Neo- 

 cene in the Northern 

 Hemisphere. The dor- 

 mice are peculiar to Eu- 

 ropean beds, and the 

 pocket-gophers to North 

 America. They cover 

 the earth, including a 

 few forms in Australia, 

 at the present period. (Fig. 50.) 



The Lagomorpha (rabbits) appear first in the lowest Neo- 

 cene of North America (White River), and continue to the 

 present day. They appear in Europe at about the same 

 time, but not in South America until the Plistocene. (Fig. 

 51.) 



The Chieopteea (bats) includes two primary divisions at 

 the present time, the insectivorous (Animalivora) and the 

 frugivorous (Frugivora), which differ as follows : 



Crowns of molar teeth Vs ; those of opposite 



Fig. 49. — Plesiartomys delicatissimus Leidy ; 

 a, humerus; 6, proximal ends of ulna and radius; 

 Cf d, tibia, distal end; e, /, astragalus ; all natural 

 size. From Eocene of "Wyoming. 



