6o THE HORSE AND ITS RELATIVES 



these occurs in the bones of the foot, and takes the 

 form of the more or less complete development of 

 one or both of the lateral toes normally represented 

 by the splint-bones. In certain instances, as has 

 been pointed out by Sir William Flower, when only 

 one of these lateral toes is developed, the abnor- 

 mality does not apparently indicate reversion to an 

 ancestral type, but seems due to a splitting of the 

 bones of the main toe. In other cases, however, 

 there seems little doubt that such supplemental toes 

 are really a reversion to the condition obtaining in 

 the extinct three-toed members of the family. An 

 instance of this kind of reversion is exhibited in the 

 foot of a shire colt formerly in the possession of 

 Lord Wantage, by whom the specimen was pre- 

 sented to the British Museum. The metacarpal 

 bones of the fore-foot are complete, although vary- 

 ing in size, and the terminal toe-bones carried 

 complete hoofs. 



Apparently this reversion to the three-toed type 

 occurs only among domesticated horses. 



A second abnormality among domesticated 

 horses is displayed by the development of rudi- 

 mentary horns, or rather horn-cores, on the fore- 

 head (pi. vii. fig. i). In his Animals and Plants 

 under Domestication^ Darwin wrote that "In 

 various countries horn-like projections have been 

 observed on the frontal bones of the horse : in 



1 Vol. i. p. 52. 



