XVI LITTORAL AND INLAND PLANTS' RELATIONSHIP 159 



one in the East African islands (Madagascar, the Mascarenes, and 

 the Seychelles), and the other in Papuasia (New Guinea, extending 

 doubtless to New Caledonia). My readers will recall to their 

 minds that zoologists have at times felt bound to postulate a 

 continent in both the centres of the genus Pandanus. There is the 

 well-known Lemuria of the Indian Ocean, and then we have in the 

 Western Pacific Forbes' Antipodea and Hedley's Melanesian 

 Plateau. 



Before, however, we accept the indications of the distribution of 

 Pandanus as favouring a continental hypothesis for either area it is 

 essential to exclude the agency of the extinct Aves. In this con- 

 nection it is of prime importance to notice that the Mascarene 

 Islands are remarkable, when contrasted with all other oceanic 

 islands, not only for the predominance of peculiar species of 

 Pandanus, but also as having been the home of extinct Columbae 

 like the dodo and the solitaire. The dodo's habit of swallowing 

 pebbles of the size of a nutmeg {Encyclop<2dia Britanjtica, vii., 322),. 

 and the solitaire's inclination for swallowing stones as large as a 

 hen's egg {Birds, by A. H. Evans, p. 331), doubtless represent, as 

 explained below, a capacity for the dispersal of large fruits and 

 seeds that would be regarded as " impossible " for distribution by 

 birds now. It is quite possible that at some time the ancestors of 

 these birds possessed the powers of flight now owned by the 

 Nicobar pigeon, in the gizzard of which, in the Solomon Islands, I 

 found quartz pebbles half an inch across {Solomon Islands, p. 324). 

 In the work just quoted I refer on page 325 to the observation of 

 Messrs. Chalmers and Gill that the Goura pigeon of New Guinea 

 usually carries a good-sized pebble in its gizzard. We do not^ 

 however, seem to possess any record of extinct Columbae in the 

 tropical islands of the Western Pacific. The nearly extinct 

 Didunculus of Samoa apparently prefers berries and soft fruits. 

 Dr. Reinecke says that it especially favours the berries of Cananga 

 odorata, the seeds of which are not over a third of an inch (8 mm.) 

 in length. 



It would appear from Mr. Hamilton's note in the Transactions 

 and Proceedings of the New Zealand Institute (vol. 24) that the 

 extinct Struthious birds of New Zealand, as in the case of the moa, 

 carried crop-stones sometimes as large as a pigeon's ^gg. These 

 pebbles are, of course, swallowed by birds to enable them to crush 

 the hard seeds, and " stones " of fleshy fruits, on which they feed- 

 In the Solomon Islands I noticed that the Nicobar pigeon was 

 able in this way to crack the seeds of Adenanthera pavonina, which 



