1909-10.] Eestoration of an Ancient British Race of Horses. 295 
Africa was regarded by M. Thomas as a member of the ass tribe and 
named Equus asinus atlanticus. 
M. Boule, who studied the small equine molars from the Pliocene and 
Pleistocene deposits of France (fig. 10) and the Pleistocene deposits of North 
Africa (fig. 9), arrived at the conclusion that the small French variety of 
Equus stenonis (sometimes known as Equus ligeris) and Eqnus asinus 
atlanticus of North Africa were intimately related, and might be regarded 
as the ancestors of the zebras now living in South Africa.* 
It thus appears that the small equine teeth found in the south of 
England were regarded by Owen as belonging to an ass or a zebra, that the 
small-pillared teeth found in France were regarded as belonging to a variety 
of Equus stenonis ( i.e . to Equus ligeris), that similar small teeth found 
in North Africa formed the type of M. Thomas’ species Equus asinus 
atlanticus, and that Equus ligeris and Equus asinus atlanticus were 
looked upon by M. Boule as the direct ancestors of some of the species of 
striped horses now living in Africa. 
From a study of the teeth alone it is difficult to decide whether the 
small equines which in Pleistocene times ranged from Algiers to England 
should be regarded as members of the ass, the zebra, or the horse section of 
the Equidae. Fortunately, the Italian, French, and English deposits which 
yielded the small -pillared teeth have also yielded small limb bones. At 
first it was impossible to say whether some of these limb bones belonged to 
an ass or to a small horse ; but by making numerous measurements it was 
eventually possible to distinguish ass from horse cannon bones, to say 
whether the horse cannon bones belonged to a slender-limbed or a coarse- 
limbed race, and from the length of the cannon bones to estimate approxi- 
mately the height at the withers. In Arabs and other slender-limbed 
modern breeds the metacarpals are decidedly narrower at the middle of the 
shaft than at the ends (fig. 13), whereas in Shires and other coarse-limbed 
breeds the shaft has nearly the same width throughout (fig. 14). Moreover, 
while in Arabs the total length of the metacarpal is from 7*20 to 7 ‘50 
times the width of the middle of the shaft, in coarse-limbed breeds — small 
Shetland ponies as well as Shires — the total length of the metacarpal is 
only from 5 ‘40 to 5*70 times the width at the middle of the shaft. 
In the Onager (a variety of which lived in Europe during the Ice age), 
the cannon bones are decidedly more slender than in the finest desert Arab, 
and even in the Kiang of Tibet the length of the metacarpal may be equal 
to 8*50 times the width of the shaft. 
* Marcellin Boule, “ Equides Fossiles.” Extrait du Bull, de la Soc. Ge'ol. de France , 3 e serie, 
tome xxvii., 1899. 
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