TRANSITION OF SPECIES. 283 



from one island to anotlier. We may therefore expect to 

 find on islands in the neighbourhood of a continent a ten'es- 

 trial fauna closely resembKng that of the continent, if the marine 

 currents are such as to favour transport from the mainland to 

 the island. Examples abound : the Galapagos have a South 

 American fauna, the Sandwich Islands a North Ameiican one. 

 Moreover, the terrestrial faixna of an island may be expected to 

 be very dissimilar from that of the nearest mainland when it 

 does not lie -within the influence of the currents flowing from it. 

 Of this too there are plenty of examples ; the best known is the 

 case of the Canary Islands ; their land mollusca have a pro- 

 nounced European character, although by their geographical 

 position they belong rather to Africa than to Europe. Attempts 

 have been made to explain this fact by an assumption that there 

 was formerly a connection between these islands and Eiu'ope 

 through Spain ; an assumption which might certaialy find much 

 to support it, if animals so large as to be incapable of being 

 transported by winds or currents, had been found in these 

 islands, either living or fossil. This, however, is not the case, and 

 it appears to me that the force and direction of the currents 

 sweeping past the^e islands amply suffice to explain the Euro- 

 pean character of the land mollusca and insects of the Canaries. 

 Supposing that a long chain of islands had connected two lands 

 lying far apart and difiering widely in their fauna, it might be 

 expected, and with great probability, that the fauna of this group 

 could have retained no special homogeneous character. For 

 the vicinity of the two terminal coimtries, and the currents pro- 

 bably existing, might easily have caused on the islands a mixture 

 of the two dissimilar faunas. This is, in fact, sometimes the case. 

 The Philippines lie very nearly north and south ; the noithern 

 islands are connected with China by the Bashees and Formosa, 

 while the southernmost island, Mindanao, is connected by 

 Celebes and some smaller islands with the Moluccas, and the 

 south-western island, Palawan, hangs on to Borneo by Balabac. 

 Wallace certainly includes the Philippines with China; the 

 Malayan peninsula, Sumatra, Java, and Borneo, with some 

 smaller islands, constitute his ' Malayan province,' which he 

 contrasts strongly with that of New Guinea and Australia, to 



