392 Z00-GEOGRAPHICAL NOTES.

which lends a charm of their own to such 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 paleontological evidence from Central Africa renders it impossible to enter upon questions of evolution, and the very incomplete acquaintance with even the existing animal life of this region permits as yet no generalisations, 1t 1s 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 1s 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 formation 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