344 GEOGRAPHICAL DISTRIBUTION 
of several species of different genera from, say, a locality in the 
north varied in the same way from examples of a set of the same 
species from the south, and so with eastern and western examples. 
In principle this was not novel or unexpected. Indeed it had been 
noticed in some instances in Europe, particularly, as the writer can 
testify, by the late Mr. Gould many years ago; but the small size 
of our own quarter of the globe compared with that of North 
America, and still more the short series of specimens which existed 
even in the largest of our collections, forbade the generalizations 
that at once became possible and almost suggested themselves 
when the vast aggregations obtained by Baird and the elder 
Agassiz were studied and compared. In the meanwhile, however, 
European, and especially English, ornithologists had been growing 
dissatisfied with the shortcomings of their coliections, and took 
pains to enlarge them, but there were special difficulties in the way 
of obtaining specimens from the eastern portion of the Palearctic 
area, and Central Asia was practically an unknown country. That 
their efforts were more or less successful may be seen by Mr. 
Dresser’s Birds of Europe, the publication of which marked an 
enormous forward stride, but still the dearth of sufficient series of 
specimens from Eastern Europe, and particularly from the Asiatic 
portion of the Russian Empire, continues to be keenly felt. The 
zeal shewn by Mr. Seebohm to meet this want deserves high 
commendation, and of late Russian ornithologists have turned their 
attention to the question of local races. The immediate effect has 
been no little confusion, but that is unavoidable, and none can 
doubt that much of it will disappear, so that we may hope our 
knowledge of the ornithology of the Palearctic area will in a few 
years be on a level with that which Americans possess as regards 
the Nearctic. Buta word of warning may be uttered in respect of 
both. Many writers on natural history find it hard to realize the 
fact, undeniable according to the principles of the doctrine of 
Evolution, that if all the individuals of any genus that ever existed 
could be set before a naturalist, he would be unable, even though 
gifted with the most critical eye, to separate them into species, for, 
however unlike the extremes might be, the means would shew an 
unbroken series between them. It must be obvious that these 
intermediate individuals are the ancestral, generalized forms, while 
the rest shew a greater and greater tendency to specialization in 
one way or another.- In the course of ages many of these inter- 
mediate forms disappear, and then it is right to regard those that 
survive without near relations as good species. But others there 
may or will be that, however they may vary locally, are still un- 
mistakably linked. ‘The forms that connect them continue the 
nearest heirs of the ancestral stock, and present its more general- 
ized features. Thus to assume, as some do, that these connecting 
