CHAPTER XX 



THE HOOK-LIPPED OR BLACK RHINOCEROS 



Rhinoceroses 



Family Rhinocerotidce 



All of the living rhinoceroses are ponderous, thick- 

 skinned mammals armed on the snout by one or two dermal 

 horns. The structure of the horns is peculiar among mam- 

 mals and quite unlike either the bony horns of the deer 

 or the hollow, chitinous horns of antelopes and their kindred. 

 The horn of the rhinoceros is made up of a compact, hard 

 mass of agglutinated, hair-like fibres which are an outgrowth 

 from the skin. The horns receive no bOny support from the 

 skull but rest on the nasal bones, where they are firmly held 

 in place by their continuity with the thick skin of the 

 snout. A slight concession, however, is made toward their 

 support by the part of the nasal bones upon which they 

 rest, this portion being set with numerous small, bony 

 tubercles. So constant are these bony tubercles that pale- 

 ontologists are enabled by such evidence to determine the 

 presence and position of horns of extinct species. The 

 horns are not strictly a family character, although so prom- 

 inent a feature of the later forms, for some of the oldest 

 genera were quite hornless. Rhinoceroses are evenly three- 

 toed, and are members of the odd-toed or perissodactyl 

 division of the hoofed mammals. In the structure of their 

 feet they are fairly closely allied to the tapirs and distantly 



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