370 Mr. Alfred R. Wallace on the 



Henicophaps has a long, straight, and powerful bill, like that of 

 some of the larger Plovers. Caloenas nicobarica I believe to 

 have spread westwards from New Guinea as far as the island 

 where it was first found and from which it has derived its name. 

 It has a massive body, with immense pectoral muscles, and very 

 stiff and ample wings, and is thus capable of passing from island 

 to island ; and it is a remarkable fact that it is found almost 

 entirely on small uninhabited islands, scattered at intervals over 

 the four thousand miles of ocean between New Ireland and the 

 Nicobar Islands. Over this wide range it presents no percep- 

 tible differences of form or colouring, which may be considered 

 to indicate that migration still takes place at intervals, and by 

 crossing the breeds in distinct islands, checks the formation of 

 local races. Phlegoenas is another beautiful genus, scattered 

 sparingly over a wide area ; but here each island has a distinct 

 species, showing that the causes that once favoured the distri- 

 bution of the form have now ceased to act. Accordingly we 

 find these birds to have a much weaker structure than Caloenas, 

 and limited powers of flight. The magnificent Crown-Pigeons, 

 the largest and most majestic of the whole order, are con- 

 fined to the Papuan islands, where they take the place of 

 the Curassows of South America. I have often seen these 

 fine birds walking along the forest-paths in New Guinea, 

 where the absence of carnivorous mammals, and the scarcity 

 of large reptiles and of birds of prey, permit them to multiply 

 unmolested. When disturbed, they fly up into the lowest 

 branches of the nearest tree, in which situations they roost ; 

 but they spend the greater part of the day upon the ground, 

 feeding on fallen fruits. The GeopelioB are small, long-tailed 

 Ground-Doves closely resembling Turtledoves in appearance, 

 but having their nearest allies in several Australian species. 

 They appear to have passed from Australia into Timor, and 

 thence along the chain of islands into Java, as they are not 

 found in any of the other parts of the archipelago. The green 

 Ground-Doves of the genus Chalcophaps are the only ones 

 which have a more extended distribution. All the species, how- 

 ever, are very closely allied ; and the one which is found in India 

 is so very similar to that of the western Malay islands, that 



