90 THE HORSE AND ITS RELATIVES 



the limbs are frequently developed. Although short 

 in summer, the coat becomes long and shaggy in 

 winter, when the mane displays a slight tendency to 

 fall to one side ; the hair on the fetlocks and lower 

 jaw likewise showing a decided increase in length 

 at the latter season. 



The dentition is characterised by the relative 

 shortness of the interval between the outermost, or 

 third, incisor and the first tooth of the cheek-series, 

 and the absolutely and relatively large size of the 

 cheek-teeth themselves, as shown in plate v. fig. i. 

 This large size of the cheek-teeth is indicated by 

 the circumstance that in a skull with a basal 

 length of i8f the length of the row of six cheek- 

 teeth is 7^ inches, or only one-quarter of an inch 

 less than that of the corresponding teeth in the 

 skull of a shire mare, of which the basal length 

 is 23 inches. Structurally the upper cheek-teeth 

 are characterised by the absence of complex 

 folding in the rings of enamel surrounding the 

 central pits, and the relatively great length of the 

 worn grinding surface of the anterior inner pillar, 

 which is produced considerably in advance of the 

 connection with the main body of the tooth, and is 

 much flattened on the inner side ; this feature being 

 more pronounced in the premolars than in the 

 molars. In a Dartmoor pony, with a skull of about 

 the same size as that of a tarpan, the length of the 

 row of cheek-teeth was only 5! inches ; but this 



