GENERAL CHARACTERISTICS. 



73 



well developed superficial gland, which exudes 

 an oily fluid with a disagreeable penetrating 

 odour. When the animal is killed in hunting 

 this gland must be at once removed with the 

 adjoining part of the skin, otherwise the 

 highly palatable flesh of the animal would 

 become quite unfit for food. 



The peccaries are nomads which roam 

 about in large troops in the forests both by 



night and by day. They are not so fond of 

 marshes as other members of the family, are 

 often found hiding in hollow trees, and support 

 each other loyally in battles against beasts 

 of prey, and especially against dogs. They 

 are very zealously hunted, but the hunters 

 always try to single out from the herd a 

 few individuals, which can then be easily 

 mastered. 



GROUP OF THE 



TWO-TOED ARTIODACTYLA OR RUMINANTS 



(DIDACTYLA OR RUMINANTIA). 



We have already drawn attention to the 

 principal characters of this group, and these 

 we will now only shortly summarize. 



The feet are always two-toed, the toes are 

 encased in hoofs and mostly articulated to a 

 single long metacarpal or metatarsal bone, 

 which is only rarely divided longitudinally, 

 but for the most part exhibits a trace of the 

 fusion that has taken place in a longitudinal 

 groove of greater or less depth. The two 

 latent digits never touch the ground, and 

 carry more or less well developed accessory 

 hoofs. But if, on the one hand, the meta- 

 carpal and metatarsal bones belonging to 

 these digits remain for the most part more 

 or less distinct, in other cases they are rudi- 

 mentary, and in others again they vanish 

 altogether with the toes themselves. There 

 is thus a series of developments by which 

 the two lateral digits get more and more 

 reduced, and this series is the continuation 

 of that which was presented by the preceding 

 group. At the same time the limbs become 

 more slender and longer, as the fleetness of 

 the animal increases. Among the ruminants 

 we meet with runners which surpass all other 

 known mammals in point of speed. 



Vol. II. 



In many ruminants there are found on the 

 hoof-bearing joints of the toes special sacs 

 formed of folds of the skin lined with hair, at 

 the bottom of which open numerous glands, 

 from which an oily, often strongly smelling, 

 fluid is exuded. The presence of these 

 so-called interdigital glands often serves to 

 distinguish genera and groups of genera. 

 The dentition displays very characteristic 

 evolutional series, but confined within pretty 

 narrow limits. In the first place there is 

 observed a tendency to dispense with the 

 upper incisors, which often begin to appear 

 in the embryo, but remain undeveloped 

 except in the camels, in which a single incisor 

 survives in each premaxilla. A callous pad 

 covering the edge of the jaw takes on the 

 function of the absent teeth. On the other 

 hand, the number of incisors in the lower jaw 

 is brought up to eight, which are united in 

 a semicircle and placed almost horizontally. 

 This increase perhaps arises in most cases 

 from the fact that the lower canine assumes 

 the form of an incisor and gets attached to 

 the series of true incisors. The upper canines 

 remain longer distinct, but in the hollow- 

 horned ruminants and the giraffes they 



42 



