1889.] On Variation. 
1079 
nessee, Cardamine laciniata ^.nd C. mitltifida. In the first of these 
the segments of the leaves are frequ^tly quite broad, sometimes 
half an inch, while in typical forms of the latter the segments are 
filiform. But I found there a series so perfectly graduated that 
the two extremes were connected by every intermediate form. In 
view of this graduated passage of one into the other, no one will 
dispute the justness of classing one as a variety of the other. The 
variety grows in dry soil, while the type form is more common 
in damp, shady places, and this difference of habitat may account 
for the differences in the leaves. 
I have quoted freely thus far from writers on zoology and upon 
botany in order to show the general recognition of the fact of 
variation among the different classes of living forms. The refer- 
ences could be multiplied to an indefinite extent, for scarcely a 
student but has recognized the fact. The remarks already made 
must make it apparent to all that variation is the rule and not the 
exception. The question arises, noting the fact of variation 
among living classes, Are we not justified in extending the same 
idea to extinct groups ? If variation is a fact in living forms, was 
it not likewise prevalent among those long since extinct ? Nay, 
may we not go further and ask. Was it not more prevalent during 
the earlier periods of the earth's history than it is at present? 
It is certainly a little remarkable that however much variation 
may be acknowledged in the living world, its presence among 
fossil forms has been largely overlooked. Whether it be the lack 
of extensive enough suites of specimens, or their very abundance, 
we can scarcely say. Most probably it is the former, combined, 
too, with the frequently fragmentary nature of the material. 
Palaeontologists generally do not seem to have taken sufficiently 
into account the great variability of species ; and with undue haste 
have rushed into print with new names that eventually add to 
the synonomy of an already overburdened science. Not that all 
are thus hasty, but too many are ; and we can congratulate the 
cautious few who hesitate before attaching their names to species 
which soon appear only in the italicized form. 
All geologists are aware that instances are not uncommon 
where species and even genera have been founded upon individ- 
