XIII EVOLUTION AND DISTRIBUTION OF ANIMALS 275 



contained only some of the lower forms of mammalian 

 life, among which the lemurs and the insectivora were 

 conspicuous. When, during the Miocene period, it be- 

 came united to Europe and Asia, it was at once overrun 

 by a number of the large mammalia of that continent, 

 such as elephants, rhinoceroses, lions, giraffes, antelopes, 

 hippopotami, apes, and many other forms whose remains 

 are found in abundance in the Miocene deposits of France, 

 Germany, Hungary, Italy, and Greece. South Europe 

 must have then possessed a sub-tropical, if not a tropical, 

 climate, the gradual deterioration of which led to the 

 extinction of most of these animals, while in Africa they 

 have survived and greatly multiplied. Among the Euro- 

 pean fossils of this period we find some of especial interest. 

 Such are, the genus Hyomoschus, mentioned by Dr. Sclater 

 as one of the Indian group of chevrotains still living 

 isolated in West Africa; a monkey, closely allied to 

 Colobus and Semnopithecus and perhaps an ancestral form 

 of these two groups which are now separated in Asia and 

 West Africa. Among birds, we have remains of the snake- 

 eating secretary bird ; Necrornis, supposed to be allied to 

 the peculiarly African plantain-eaters ; and a parrot allied 

 to the well-known grey parrots of Africa. Here, then, we 

 have traced tlae origin of the resemblances between cer- 

 tain animal forms of tropical Asia and West Africa to 

 their having been derived from a common source in the 

 great northern continent, and we are justified in supposing 

 that the Fitta angolensis is also a descendant of one of 

 these Miocene forms. A species of Pitta even now inhabits 

 Japan, so that we may well suppose the genus to have 

 originated in Europe or Western Asia in the warm 

 Miocene period. It was probably once more abundant in 

 Africa, but, along with the Hyomoschus and the crested 

 hornbill, is now in process of extinction in the one conti- 

 nent, while its allies continue to flourish in the other. 



The Frohlem of Allied Forms in all the Tropical Regions. 



Leaving for the present the next three cases of 

 difficulty adduced by Dr. Sclater, we will pass on to the 



T 2 



