GEOGRAPHICAL DISTRIBUTION 345 
forms are the result of interbreeding between the extremes is 
to begin at the wrong end, and virtually to mistake cause for 
effect.1 In reality there is no need to make any assumption whatever. 
It is far better, certainly at the present time, to stick to the plain 
facts of each case, so far as we can acquaint ourselves with them, 
and there is every appearance of each case having to be treated 
upon its own merits. But opportunities for generalization will, of 
course, come at last, and meanwhile we shall possibly not be far 
wrong in expecting, as one result of the facts already known and 
undoubtedly to be multiplied by increased observation, an elucida- 
tion of what has seemed to so many an insoluble puzzle—the 
repetition, so to speak, of similar forms in Western Europe and in 
Eastern Asia without their appearance in the intermediate terri- 
tory, or cases of, to use another expression, “interrupted distribu- 
tion ”—be the interruption as in that of Cyanopica, already 
mentioned, absolute, or modified more or less as in so many other 
instances. 
V. The Ethiopian Region is by no means easily divided. In 
treating of it in 1875 (Encyclop. Brit. ed. 9, iii. pp. 757-760), the 
present writer followed in the main the guidance kindly afforded 
him by Dr. Sharpe, whose knowledge of its Avifauna is hardly, if at 
all, exceeded by that of any other ornithologist, and recognized five 
Subregions. The progress of geographical discovery, which has of 
late years laid open so much of the wilds of Central Africa, has 
shewn a much greater homogeneity than was before expected in the 
_ Fauna of the several parts of that continent, though it is true that 
the explorers of its interior have in few cases had any zoological 
knowledge or even taste, and that to at least one of the most cele- 
brated of them scientific research of any kind is repellent. It must 
also be remembered that nearly all of those few zoological explorers 
have forfeited their life? in their zeal for investigation, and, with 
the notable exception of Emin Pasha, scarcely one has survived to 
carry on his observations or to make collections for any length of 
time. Consequently the vast area of Equatorial Africa, and the 
districts immediately conterminous, are ornithologically almost 
unknown. Meanwhile we do know that nearly all the most 
1 The seeming inability to grasp this position detracts greatly from the 
value of nearly all that Mr. Seebohm has written on the geographical distribu- 
tion of birds in the Palearctic Subregion and elsewhere, leading him to con- 
clusions of the most erroneous kind, which have been uncritically accepted by 
several other writers. 
2 It would be impossible here to name even the naturalists who from Mungo 
Park downwards have fallen victims to African exploration ; yet, in an ornitho- 
logical work, William Alexander Forbes must be especially mentioned, as it was 
the pure love of ornithology that led him up the Niger, where he suecumbed ta 
fever in the very prime of life. 
