1835.] WADERS AND WATER-BIRDS. 375 



a most singular group of finches, related to each other in 

 the structure of their beaks, short tails, form of body, and 

 plumage : there are thirteen species, which Mr. Gould has 

 divided into four sub-groups. All these species are peculiar 

 to this archipelago ; and so is the whole group, with the 

 exception of one species of the sub-group Cactornis, lately 

 brought from Bow Island, in the Low Archipelago. Of 

 Cactornis, the two species may be often seen climbing about 

 the flowers of the great cactus-trees ; but all the other species 

 of this group of finches, mingled together in flocks, feed on 

 the dry and sterile ground of the lower districts. The males 

 of all, or certainly of the greater number, are jet black ; and 

 the females (with perhaps one or two exceptions) are brown. 

 The most curious fact is the perfect gradation in the size of 

 the beaks in the different species of Geospiza from one as large 

 as that of a hawfinch to that of a chafiinch, and (if Mr. Gould 

 is right in including his sub-group, Cetthidea, in the main 

 group), even to that of a warbler. The beak of Cactornis 

 is somewhat like that of a starling ; and that of the fourth 

 sub-group, Camarhynchus, is slightly parrot-shaped. Seeing 

 this gradation and diversity of structure in one small, inti' 

 mately related group of birds, one might really fancy that 

 from an original paucity of birds in this archipelago, one 

 species had been taken and modified for different ends. 

 Jn a like manner it might be fancied that a bird, origin- 

 ally a buzzard, had been induced here to undertake the 

 office of the carrion-feeding Polybori of the American 

 continent. 



Of waders and water-birds I was able to get only eleven 

 kinds, and of these only three (including a rail confined to 

 the damp summits of the islands) are new species. Con- 

 sidering the wandering habits of the gulls, I was surprised 

 to find that the species inhabiting these islands is peculiar, 

 but allied to one from the southern parts of South America. 

 The far greater peculiarity of the land-birds, namely, twenty- 

 five out of twenty-six being new species or at least new 

 races, compared with the waders and web-footed birds, is 

 in accordance with the greater range which these latter 

 rjrders have in all parts of the world. We shall hereafter 

 see this law of aquatic forms, whether marine or fresh- 

 water, being less peculiar at any given point of the earth's 

 surface than the terrestrial forms of the same classes, 

 strikingly illustrated in the shells, and in a lesser degree 

 in the insect* of this archipelagc. 



