PECORA. G9 
quadrangular, and complex, the enamel-foldings being numerous 
as compared with the simpler ones of Rhinoceroses and Tapirs. 
The wild species inhabit the plains of Asia and Africa. 
The cases numbered 38 and 37, with the central case H, 
contain specimens of several members of the family, as, 
for instance, the true Zebra, Equus zebra ( 1024 ) ; Grevy^s 
Zebra, E. grevi/i ( 1025 ); some of the local races of the Bonte 
Quagga or Burchell’s Zebra, E. hurclielli ( 1018 ), distinguished 
l)y the different arrangement of the stripes on the body ; and a 
specimen of the true Quagga, E. quagga ( 1017 ), now extinct. 
Two varieties of the African Wild Ass, Equus asinus ( 1014 , 
1015), the ancestral form of the domesticated breeds, are also 
exhibited. In the same case are shown specimens of the Kiang 
of Tibet, Equus kiang ( 1013 ), and of the wild Mongolian Horse, 
E. cahallus przeioalskii ( 1016 ). 
Suborder Artiodactyla. 
The Artiodactyla, or Even-toed Ungulates, are so called 
because their feet always possess an even number of toes, two 
or four, the centre line of the foot passing down between the 
toes which correspond to the third and fourth of the complete 
or typical five-toed mammars foot. These two toes are always 
equal, and larger than the second and fifth, if those are 
present, the first being absent. The metacarpal and meta- 
tarsal bones of the third and fourth digits are generally united, 
und form a “ cannon-bone.^’ The premolars and molars are 
distinct in shape, the former being single- and the latter two- 
lobed. The dorsal and lumbar vertebrae together invariably 
number nineteen. 
Artiodactyla, which are extraordinarily numerous both in 
genera, species, and individuals, are divided into four chief 
groups or sections, namely : (1) Pecora, or Oxen, Sheep, Ante- 
lopes, Giraffes and Deer ; (2) Tylopoda, or Camels and Llamas ; 
(3) Tragulina, or Ohevrotains ; and (4) Suina, or Hippo- 
potamuses, Peccaries, and Pigs. 
In the first three of these the molars consist of two pairs of 
[Cases 
40 to 40 
and West 
Corridor.] 
