132 SCLATER ON THE GENERAL DISTRIBUTION OE AVES. 



of zoology and botany than we as yet possess, before it can be 

 told with certainty what are the primary ontological divisions of 

 the globe. We want far more correct information concerning the 

 families, genera, and species of created beings — their exact locali- 

 ties, and the geographical areas over which they extend — before 

 very satisfactory conclusions can be arrived at on this point. In 

 fact, not only families, genera, and species, but even local varieties 

 must be fully worked out in order to accomplish the perfect solu- 

 tion of the problem. There is no reason, however, why attempts 

 should not be made to solve the question, even from our present 

 imperfect data, and I think the most likely way to make good 

 progress in this direction, is for each inquirer to take up the 

 subject with which he is best acquainted, and to work out what 

 he conceives to be the most natural divisions oi the earth's surface 

 from that alone. Such being done, we shall see how far the results 

 correspond, and on combining the whole, may possibly arrive at a 

 correct solution of the problem — to find the primary ontological 

 divisions of the earth'' s surface. 



With these views, taking only the second group of the Order 

 Yertebrata, the Class Aves, I shall attempt to point out what I 

 consider to be the most natural division of the earth's surface into 

 primary kingdoms or provinces, looking only to the geographical 

 distribution of the families, genera, and species of this class of 

 beings. 



Birds, being of all the animated creation the class most parti- 

 cularly adapted for wide and rapid locomotion, would, at first sight, 

 seem to be by no means a favourable part of Nature's subjects 

 for the solution of such a problem. But, in fact, we know that 

 there are many species, genera, and even families of this class, par- 

 ticularly amongst the JPasseres^ whose distribution is extremely 

 local. The Nestor productus, confined to the little island called 

 Philip Island ; the several genera of T'inches peculiar to the archi- 

 pelago of the Galapagos ; the gorgeous family Paradiseidcd, re- 

 stricted to the Papuan territory, are familiar examples of this fact. 

 Again, the migratory birds which traverse large districts of the 

 earth's surface, how constant are they in returning only where 

 they have been in former years ! We do not find that the 

 Nightingale extends its range farther to the west one year than 

 another, nor that birds looked upon as occasional visitors to this 

 country, grow more or less frequent. If the contrary be the case, 

 it may always be accounted for by some external cause, generally 

 referable to the agency of man, and not to any change in Na- 



