c:hap. XXIV.] INSULAR FORMS OF BIRDS. 6 7 



modification exactly opposite to that which produced 

 the wingless birds (the Apteryx, Cassowary, and Dodo), 

 appears to have here taken place ; and it is curious that 

 in both cases an insular habitat should have been the 

 moving cause. The explanation is probably the same as 

 that applied by Mr. Darwin to the case of the Madeira 

 Vieetles, many of which are wingless, while some of the 

 winged ones have the wings better developed than the 

 same species on the continent. It was advantageous to 

 these insects either never to fly at all, and thus not run 

 the risk of being blown out to sea, or to fly so well as to 

 be able either to return to land, or to migrate safely to the 

 continent. Bad flying was worse than not flying at all. 

 So, while in such islands as New Zealand and Mauritius, 

 far from all land, it was safer for a ground-feeding bird 

 not to fly at all, and the short-winged individuals con- 

 tinually surviving, prepared the wny for a wingless group 

 of birds ; in a vast Archipelago thickly strewn with 

 islands and islets it was advantageous to be able occa- 

 sionally to migrate, and thus the long and strong-winged 

 varieties maintained their existence longest, and ultimately 

 supplanted all others, and spread the race over the whole 

 Archipelago. 



Besides this pigeon, the only new bird I obtained during 

 the trip was a rare goat-sucker (Batrachostoraus crinifrons), 

 the only species of the genus yet found in the Moluccas. 



f2 



