80 TRANSACTIONS OF THE [FEB. 23, 
been based. Again, the increase of material from new localities 
showed that certain forms described as species gradually varied 
in the direction of other species, through specimens from inter- 
mediate points of the common habitat. In other words, we be- 
gan to be troubled with a lot of specimens that were variously 
intermediate between two or more previously supposed wholly 
distinct species. This occurred not merely in a few isolated 
cases, but frequently over most of the continent. Under these 
circumstances, and in the light already thrown upon the general 
subject, it was natural that many species which had been held for 
years in good standing—or while known from only a few speci- 
mens—should be reduced either to pure synonyms or to the rank 
of geographical forms or subspecies. It was further natural that 
in some instances it should be presumed, on general grounds, 
that certain of the previously recognized species were either 
purely nominal or else only local forms, even where the evidence 
was far from conclusive. For atime, under the new order of 
things, it was not strange that undue lumping should result, 
as later researches have proved was the case. 
«Intermediates ” were at first explained on the ground of hy- 
bridity, and it was customary for atime to treat the few refractory 
specimens then known as hybrids. But the hybrids soon became 
troublesomely numerous ; furthermore, it was noticed that over 
certain areas, and along certain geographical lines, the varia- 
tions were in general of a similar character. As already said, 
this gave rise to the recognition of certain laws of geographical 
variation. A crisis resulted respecting methods of treatment, 
culminating about 1870. Down to about this date a collec- 
tion of individuals known as a species was, theoretically at least, 
a distinct and definable group. Varieties, in a geographical 
sense, were rarely recognized, and ‘‘ subspecies” was an almost 
unknown term. Many species to which we had long pinned our 
faith were turning out badly ; instead of being stable and well 
marked, they were found to intergrade with others from which 
they were supposed to be distinct. This, of course, was always 
in the case of closely allied species ; between many other species 
no such intergradation was apparent. Thus we had, as it 
were, two kinds of species, some which intergraded and some 
which did not intergrade. How were such diverse elements to 
be treated ? This was the question of the hour. Should these 
strongly marked geographical forms be lumped together under 
a common specific name and thus wholly ignored in nomencla- 
ture, or should we continue to recognize under binomial names 
all strongly marked forms characterizing particular physio- 
graphic areas—in other words, forms having approximately defin- 
