THE ODD-TOED UNGULATES. 



ridges on the bones of the limbs, and especi- 

 ally the third trochanter on the thigh, are 

 enormous ; even the ribs have oblique middle 

 ridges throughout their entire length. 



The dentition is characterized by the want 

 of constancy in the front teeth, and the 

 peculiar form of the enamel folds in the 

 cheek-teeth. The canines are always want- 

 ing, so that a considerable interval separates 

 the cheek-teeth from the incisors, which were 

 originally (in fossil forms) four or evert six 

 in number both above and below. The 

 rhinoceroses of the present day have at first 

 two incisors in each half of the jaw, but their 

 subsequent development varies greatly. In 

 the upper jaw the incisors are very close-set; 

 the outer pair are the smaller and first dis- 

 appear. In the lower jaw the incisors are 

 conical, almost horizontal, and directed for- 

 wards ; the outer ones are often very strong, 

 and in some fossil species developed almost in 

 the form of tusks. They persist the longest; 

 while the inner ones drop out early, although 

 always subsequently to the shedding of the 

 outer incisors of the upper jaw. At last all 

 the incisors disappear and are never replaced. 

 We thus have species in which there are only 

 two incisors above and four below; others in 

 which only two incisors are found below in 

 the adult ; and others again in which they are 

 latterly altogether wanting, and in which the 

 callous margins of the gum serve to root up 

 plants. In the young animal the various stages 

 of this gradual reduction can be observed. 

 The cheek-teeth are seven in number in each 

 half of each jaw, in all twenty-eight, but they 

 are very diverse in their nature. The upper 

 ones are much larger than the lower. They 

 have two irregular transverse prominences, 

 which are separated on the inside by a deep 

 winding fissure, but on the outside are con- 

 nected by a longitudinal fold. When the tooth 

 has been worn down to some extent these pro- 

 minences seem to be surrounded by a con- 

 tinuous curiously-twisted strip of enamel. The 

 lower cheek-teeth are longer than broad, and 



exhibit two sickle-shaped bodies surrounded 

 by enamel, these bodies standing obliquely be- 

 hind one another and having their convexity 

 behind. 



Among the internal parts of the organization 

 we may take note of the relatively small 

 simple stomach, the enormous colon and 

 caecum, the small brain, the two -horned 

 uterus, the two inguinal teats, and the diffuse 

 placenta. The female remains pregnant 

 seventeen months, and brings forth a single 

 young one, which is defended by the mother 

 with fury. The horn begins to grow only 

 when the young animal has advanced a little 

 in age ; the new-born animal has only a slight 

 swelling on the nose, such as characterized 

 the hornless ancestors of our present rhino- 

 ceroses (Aceratherium) throughout life. 



The habits of these dull, stupid, and clumsy 

 but powerful animals are almost everywhere 

 the same. They are exclusively herbivorous ; 

 but while most of them prefer marshy woods, 

 the jungle, and the banks of rivers and ponds 

 where they can wallow in the mud, we have 

 African species (Rh. simus) which show a 

 preference for the steppes with dry stiff 

 grasses. But in general rhinoceroses require 

 water and mud if it is for nothing else than 

 to defend themselves against the insects which 

 torment them in spite of the thickness of 

 their hide. These giants have no enemy to 

 fear except man. Lions and tigers go out 

 of their way, for their horns and feet are 

 terrible weapons, and when once a rhino- 

 ceros has broken out into fury nothing can 

 withstand the violence of his onslaughts. 

 With head down he darts upon his enemy, 

 throws him to the ground, and tramples him 

 under his feet. We have heard of battles 

 between elephants and rhinoceroses, but no 

 recent observer has ever witnessed one. But 

 it appears that these two giants of the forest 

 shun one another, although in Quaternary 

 times the mammoth and the rhinoceros with 

 bony nasal septum manifestly lived together 

 as peaceable neighbours. 



