Coryndon[1] that the calf of Rh. simus "always runs in front of the cow, while the calf of Rh. bicornis invariably follows its mother." Both animals of course have two horns, and upon the varying proportions of the horns a large number of "species" have been made in the past. It is stated that the longest horn of the "White Rhinoceros" known measures 56½ inches; while that of R. bicornis is shorter, 40 inches being apparently the maximum. But the animal is smaller.
Fig. 133.—Head of Rhinoceros bicornis.
The possible third African species of Rhinoceros[2] has been provisionally named after Mr. Holmwood, and is based upon two horns 41 and 42 inches long, which may be abnormal horns of Rh. bicornis; but they are thinner and have a smaller pedicel.
Extinct Rhinocerotidae.—The existing Rhinoceroses are thus confined to Africa, to certain parts of the continent of Asia, and to some of the large islands lying to the south of that continent. But formerly the genus, and allied genera, had a wider range. As far back as the Miocene we meet with remains of Rhinoceroses closely allied to existing forms. The more ancient forms have, as is natural, more ancient characters. Thus in Rh. schleiermacheri of the Miocene, canines appear to have been present. The Miocene Aceratherium, primitive in the absence of horns as its
