622 UNGULATA. 



keep pace with their eager and hungrily active followers, and so are 

 forced to drop into the rear. The hindermost animals in the meantime 

 are anxiously pushing forward in search of food, so that there is a con- 

 tinual interchange going on as the herd moves onward, tliose in tront 

 dropping back to the rear, while those in the rear are constantly press- 

 ing forward to take their place In front. 



In size the Spring-bok is rather superior to the Dorcas gazelle, but 

 ma}- be immediately distinguished from that animal by means ot a curious 

 white patch of long hairs on the croup. Although the animal is so mar- 

 velously agile, the body is rather clumsily formed, and seems to be dis- 

 proportionately large when contrasted with the slight and delicate limbs 

 on which it is supported. While standing at rest, the Spring-bok may 

 be recognized by the peculiar line of the back, which is more elevated 

 at the croup than at the shoulders. The horns of this animal are much 

 larger in the adult male than in the young or the female, and when full 

 grown, are marked with eighteen or twentv narrow complete rings. 

 The lyrate form of the horns is not so perceptible in the young Spring- 

 bok as in the older animal, for until the creature has attained its full 

 growth, the tips of the horns point forward. 



GENUS PROCAPRA. 



The tzvo species of this genus inhabit Mongol-Tartary and the steppes 

 between China and Thibet. 



The DSEREN, Procapra guitiirosa, stand about two feet and a half liigh, 

 and measures about four feet and a half in length. The body is slender, 

 the head short and thick ; the throat of the males has a large protuber- 

 ance, the tail is short, and its upper pari covered with curly hair ; the 

 legs are slender and graceful ; the horns, which are borne only by the 

 males, are placed close together on the skull, but gradually widen out, 

 curving backward and inward, and marked at the base with about 

 twenty prominent rings. The ears are large and pointed. The color of 

 the coat varies according to the season. In summer the throat and the 

 thighs below the tail are pure white, and the rest of the body is cream- 

 color, with some brownish marks on the brow. The winter coat is 

 uniformly lighter. The hair is very thick, and longer on the hind- 

 quarters than in front. 



These animals are usually hunted in the winter season, when they 



