224 THE MALAGASY REGION. [CHAP. 



been found in the island. After remarking that bush-pigs are 

 stated to be more aquatic in their habits than ordinary swine, Dr 

 Blanford 1 asks "how far could Potamochxrus swim? Surely it 

 is not likely that it could cross the Straits of Dover. I think we 

 are justified in assuming about ten miles as a probable limit of its 

 power of crossing the sea, but, to be safe, let us suppose double as 

 much. Then, in Pliocene or Plistocene times, quite as probably 

 the latter as the former, when Potamochczmis reached South Africa, 

 Madagascar was separated by a channel not more than twenty 

 miles broad. The conclusion is inevitable, that nearly the whole 

 depression of upwards of a thousand fathoms is of Pliocene or 

 Post-pliocene date. Of course it must not be assumed that this 

 date is proved. What we may consider, however, as beyond any 

 doubt is that the depression cannot be older than the Middle 

 Tertiary." This view may be taken as practically identical with 

 the one here advanced, namely that Africa and Madagascar were 

 united till the period of the upper Oligocene or Miocene. 



With the exception of the fruit-bats and Daubenton's civet, 

 which, as already mentioned, is more nearly allied to the Oriental 

 rasse than to the Ethiopian Viverridce, the Malagasy mammals do 

 not exhibit any well-marked alliance with those of India. But the 

 case is different with the birds, molluscs, and certain other groups ; 

 while we have no evidence that giant land-tortoises ever inhabited 

 the African mainland, although an extinct species is known from 

 the Indian Pliocene. 



Basing his conclusion on evidence drawn from several sources, 

 Dr Blanford, in the communication last cited, is of opinion that 

 there was formerly a direct land-connection between India and 

 South Africa, and that this connection "included the Archaean 

 masses of the Seychelles and Madagascar, that it continued 

 throughout upper Cretaceous times, and was broken up into 

 islands at an early Tertiary date. Great depression must have 

 taken place, and the last remnants of the islands are now doubt- 

 less marked by the coral atolls of the Laccadives, Maldives, and 

 Chagos, and by the Saya de Malha bank. It is immaterial 

 whether Bourbon, Mauritius, and Rodriguez ever formed part of 



1 Appendix, No. 8, p. 88. 



