80 TRANSACTIONS OF THE [FEB. 23, 



been based. Again, tlie 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 a time, 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- 

 brid ity, and it was customary for a time 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- 



