THE COLLECTION OF FOSSIL VERTEBRATES 5 
or collateral ancestors of the modern Horses, Asses and Zebras, 
are in one alcove, arranged in series from the most ancient to 
the most recent. The most ancient and structurally primitive 
groups of mammals come first, the most modern and familiar 
types come last. 
Soutu (Ricut) Sipe. Nortu (Lert) SIDE. 
if TITANOTHERES AMBLYPODS ' Primitive Hoofed 
| Chalicotheres CONDYLARTHS Mammals 
Monkeys, Bats, Rodents, Insectivores 
and other Small Primitive Mammals 
Marsupials 
CREODONTS — } Carnivorous 
CARNIVORES ) Mammals 
Seals, Dolphins, Whales, } Marine 
eteadact yi Sirenians ete. ) Mammals 
erisso ris : 3 
Tapirs MASTODONS and } ee esacidie 
or Odd-Toed 5 1, phiodonts Sian {ooo 
Hoofed | RHINOCEROSES ELOTHERES  } 
Mammals Artiodactyls 
or 
Anthracotheres 
Pigs and Peccaries { 
OREODONTS | Even-Toed 
~ 
CAM E LS Hoofed 
Palzotheres DEER ete. Mammals 
HORSES oe Fossil Mammals 
brain | Peculiar to South 
EDENTATA J America. 
SOUTH (RIGHT) SIDE. 
The south side of the hall is entirely devoted to the PErts- 
SODACTYLS or Odd-Toed Hoofed Mammals in which the number 
of toes (in the hind foot and generally in the forefoot) is either 
I, 3 or 5, while in the other main division of hoofed animals, the 
Artiodactyls, it is either 2 or 4; or more exactly, the axis of 
symmetry of the foot passes through the central toe in Peris- 
sodactyls, while in Artiodactyls it passes between two toes. 
The TITANOTHERES come first in the series of Perissodactyla, 
large animals which suggest rhinoceroses in general goin al 
proportions, but have a differently shaped head and cove 1, 
peculiar teeth. These began as hornless animals of Titan- 
moderate size (Cases 1 and 17) and increased in size 1 ty 
and developed large bony horns (Cases 3, 5 and 19) before they 
