Sivalensis and R.
Meanwhile the researches of Hugh Falconer (1808-1865) and of Proby Thomas Cautley (1802-1871) in the sub-Himalayas brought to light the marvellous fauna of the Siwalik hills of India, published in Fauna antiqua Sivalensis (London, 1845) and in the volumes of Falconer's individual researches.
Possibly this Russian camel (Procamelus khersonensis), as it is called, may form the connecting link between the typical Procamelus of North America and the fossil camel (Camelus sivalensis) of the Siwalik Hills of India.
Sivalensis, which may have been the ancestral form.
Sivalensis), occurs in the Lower Pliocene, and may have been the ancestor of the Arab stock, which shows traces of the depression in front of the orbit characteristic of the earlier forms. In North America species of Equus occur in the Pleistocene and from that continent others reached South America during the same epoch.