312 GEOGRAPHICAL DISTRIBUTION 



should. He took up the branch of the subject with which he 

 Avas best acquainted, and pointed out and defined the liegious 

 of the globe in conformity with the various aspects of ornithic 

 life as known to him. But herein there was at once a great dii'ii- 

 culty to be met. Birds constituting the most vagrant Class of 

 animals in existence, it was necessary for him to eliminate from 

 consideration those groups of them, be they large or small, whicli 

 are of more or less universal occurrence,^ and to ground his results 

 on Avhat was at that time commonly known as the Order Insessore^, 

 comprehending those birds that are now generally differentiated as 

 the groups or Orders, Fasseres, Ficarm, and Fsittaci. 



On this basis, then, Mr. Sclater, after dwelling on the great 

 distinction he thought observable between the Fauna of the Old 

 World and of the New, was enabled to set forth that the surface of 

 the globe exhibited six great Regions, each in a marked manner 

 differing from all the rest, though the difference was not always 

 equally important. These Regions he termed respectively the 

 Falxardic, Ethiopian, Indian, Australian, Neardic, and Neotropical — 

 names which, so far as may be possible, it is convenient to preserve — 

 and proof that the method he followed was the true one is afforded 

 by the fact that these Regions have met with very general acceptance 

 at the hands of those who study other groups of animals.'^ Without, 



^ Not but that even in the most widely-spread groups are contained others — 

 subfamilies, genera, or species — strictly limited to certain localities. Some of 

 them will be noticed further on. 



- This is a thing on which few writers seem to have dwelt sufficiently. What- 

 ever be the causes, and it would be out of place here to discuss them, it must be 

 admitted that what may be taken as a "law" of Geographical Distribution for 

 one group of beings is not necessarily applicable to other groups. Botanists 

 have shewn no disposition to accept the territorial divisions of their zoological 

 brethren. It seems difficult to defend the position so often assumed that the 

 boundaries set up for one group of animals are true for another, or still less that 

 they are universally true. This fact has indeed had to be recognized in the case 

 of some marine forms — for instance, Fishes, which, it is confessed, cannot be made 

 subject to the limitations of terrestrial fornis {cf. Giinther, Introduction to the 

 Study of Fishes, pp. 259, 260), though Dr. Gill {Ann. and Mag. Nat. Hist. ser. 4, 

 XV. pp. 254, 255) recognizes for this Class what are practically the same divisions 

 as those of Prof. Huxley — Xew ZLalaiid, however, being placed with Australia. 

 As regards the Land-Mollusks, malacologists demur to the general principles of 

 Distribution which students of most Classes of Vertebrates accept, while even 

 among \'ertebrates themselves, and eicludiug Fishes, what is the best division 

 of the Earth's surface into Regions, Subregions, Provinces and so on, for Birds 

 may not be the best for Mammals, Reptiles, or Amphibians. It would apjjear 

 [)relcrable to consider the case of each of these Classes on its own merits, and 

 thus in what follows the territorial divisions adopted are in accordance with 

 what it is supposed we know or seem to know of the Class Aves, and it ma}' 

 even be open to question whether the best division for one Subclass or Order of 

 Birds is the best for another. 



