392 ZOO-GEOGRAPHICAL NOTES. 



which lends a charm of their own to snch considerations ; 

 various and manifold are the unsolved questions relating to 

 the distribution of individual families, the physical conditions 

 which have brought about their migrations, the apparently 

 spontaneous appearance of forms in places where they are 

 separated from all their relations by large tracts of country, 

 and finally the coincidence or otherwise of faunistic with floral 

 regions. 



Whereas the almost total absence of palgeontological evidence 

 from Central Africa renders it impossible to enter upon ques- 

 tions of evolution, and the very incomplete acquaintance with 

 even the existing animal life of this region permits as yet no 

 generalisations, it is the more desirable to compensate in some 

 measure for this deficiency by work in detail. First and 

 foremost in this work is, of course, the compilation of accurate 

 special lists for circumscribed divisions of the country as a 

 basis for a general survey. The material for such work is 

 only gained by diligent collecting. But another exceedingly 

 profitable task offers itself to the explorer in the application 

 of the collected facts to zoo-geographical purposes. Wallace 

 has defined the zoological provinces of the African continent 

 with a master hand, and, on the whole, there is nothing to 

 alter or find fault with in his arrangement. We have next to 

 ascertain how the boundaries of these provinces are situated 

 with regard to one another, at which parallels of latitude 

 and longitude the transitions take place, and whether they 

 are sharply pronounced or become gradually perceptible. As a 

 matter of course, there are numerous questions connected with 

 this inquiry concerning the relation between the physical for- 

 mation of the country, its vegetation, and its fauna. 



While, from what has been said, it is evident that a large 

 and productive field awaits the worker, it must be clearly 

 understood that the following lines, which relate to a very 

 limited region, are only an attempt to contribute some little to 

 the solution of debated questions, and that they were written 

 in the heart of Africa. Moreover, the data given are confined 

 chiefly to ornithological facts, because the birds of the country 

 have been more thoroughly investigated than other animals. 



If migration be taken in its widest sense as a periodical 



