GEOLOGIC HORIZONS AND LIFE ZONES. 



13 



Lower Harrison, Western Nebraska. 



A number of species of horses have been found by Harold Cook in the Lower Harrison but have not yet been deter- 

 mined or described. They represent the genera Parahippus and Kalobatippus. 



Type of Kalobatippus agatensis Osborn, 1918. Type of Parahippus tyleri Loomis, 1908.2. 



Lower Rosebud, South Dakota. 



Type of Miohippus equinanus Osborn, 1918.3. Type of Parahippus pristinus Osborn, 1918.1. 



" gcmmarosa? Osborn, 1918.4. 



Merycochcerus-Parahippus Zone. Lower Miocene. Burdigalian of Europe. 



This life zone is distinguished by the first appearance of the widespread oreodont genus Merycochosrus, a genus which 

 survives into the Middle Miocene, also by the abundance of Parahippus, and by camels of more advanced type (Oxy- 

 daclyhis). Oxydactylns, Ticholeptus, Blastomeryx first appear here. 



1. Horizon D of Hayden, 18(39. 



2. Upper Harrison formation, western Nebraska, Hatcher 1902, Peterson, 1906. 



3. Upper Rosebud, South Dakota, Matthew, 1904. 



4. Martin Canon beds, northeastern Colorado, Matthew, 1901. 



5. Laramie Peak, Wyoming. 



Upper Harrison. 



Type of Parahippus nebrascensis Peterson, 1907.3. Type of Parahippus nebrascensis primus Osborn, 1918.4. 



Type of Parahippus pawniensis atavus Osborn, 1918.3. 



Upper Rosebud. 

 Type of Parahippus eoloradcnsis prcecurrens Osborn, 1917.2. 



Washington Co. (Incertae sedis), Texas. 

 Type of Parahippus texanus Leidy, 1S6S. Type of Parahippus australis Leidy, 1873.1. 



