I 
28 THE INTERNATIONAL MONTHLY. 
grossest and most palpable of which may be readily detected. 
The third method of prosecuting genealogical research is that 
of palaeontology, or the study of fossils. This method, while by 
no means free from difficulties and drawbacks, has certain pre- 
eminent advantages which admirably fit it to supplement the 
deficiencies of the other methods, just as the latter, in their turn, 
supplement the deficiencies of palaeontology. What are some of 
these deficiencies ? There is, in the first place, the incomplete- 
ness of the geological record. Palaeontology cannot hope to 
reconstruct the whole history of life upon the earth, or even the 
greater part of that history, for many of its chapters are irretriev- 
ably lost, while others are so fragmentary as to be unintelligible. 
Nearly the whole recorded history of life is contained in rocks 
which were laid down under water and especially those which were 
accumulated in the bed of the sea, and the preservation of a land 
animal under such conditions is simply a lucky accident. We 
have every reason to feel assured that the land was covered with 
a luxuriant vegetation ages before the date of the oldest known 
fossil land plant. Even in an uninterrupted series of marine 
deposits, representing vast periods of time, there are sure to be 
gaps in the record of life, even for the restricted area. Changes in the 
depth of water, in the character of the bottom, or in the config- 
uration of the adjoining land will drive away one set of animals and 
bring in another set that is not derived from the former, while 
the first set may return upon a renewal of the old conditions. 
Again, many kinds of animals are quite incapable of pres- 
ervation in the fossil state, save under the most exceptional 
conditions, — conditions which recur so seldom and so widely 
separated both in space and time, as to render useless any attempt 
to construct a continuous story from them. 
In the second place, those animals which are fossilized are, in 
almost all cases, very incompletely preserved. Except under 
exceedingly rare circumstances, in late periods of the earth's 
history, only the hard parts, such as shells, bones, teeth, and scales, 
are preserved. It is rare to find even a whole skeleton, and great 
numbers of fossil animals are known only from a few teeth or scat- 
