June, 1891 . 
ANIMAL PEDIGREES. 
125 
said elsewhere and by others, for it seems to me that zoologists 
are too apt nowadays to neglect palaeontology, while palaeon¬ 
tologists have a tendency to regard embryology as something 
beyond their own ken, and concerning them but little. 
Moreover, there are certain points arising from a study of 
fossils which, I venture to think, may possibly commend 
themselves to some of our members as suitable subjects for 
practical investigation. 
The elder Agassiz was the first to point out, in 1858, the 
remarkable agreement between the embryonic growth of 
animals and their palaeontological history. He called atten¬ 
tion to the resemblance between certain stages in the growth 
of young fish and their fossil representatives, and attempted 
to establish, with regard to fish, a correspondence between 
their palaeontological sequence and the successive stages of 
embrvonic development. He then extended his observations 
*' X. 
to other groups of animals, and stated his conclusions in 
these words :—“It may therefore be considered as a general 
fact, very likely to be more fully illustrated as investigations 
cover a wider ground, that the phases of development of all 
living animals correspond to the order of succession of their 
extinct representatives in past geological times. 1 ’ 
This point of view is of great importance. If the develop¬ 
ment of an animal is really a repetition or recapitulation of 
its ancestral history, then it is clear that the agreement or 
parallelism which Agassiz insists on between the embryo- 
logical and palaeontological records must hold good ; and a 
most important field of work is thus opened up to us. 
It is sometimes urged, however, that such work is neces¬ 
sarily unfruitful and inconclusive, because of the scantiness 
of our knowledge concerning life in the earlier geologic 
periods, or, as it is commonly termed, the imperfection of the 
geological record. I have elsewhere protested against this 
objection, and would repeat my protest here. The actual 
number of fossils already obtained, especially from the more 
recent formations, is prodigious; and what we have to do is 
to make the most of the material already accumulated, rather 
than to fold our hands and idly lament the absence of forms 
that perhaps never existed. 
It is true that with all groups the chances are not equal. 
But, by judicious selection of groups in which long series of 
specimens can be obtained, and in which the hard skeletal 
parts, which alone can be suitably preserved as fossils, afford 
reliable indications of zoological affinity, it is possible to test 
directly this alleged correspondence between the palaeonto¬ 
logical and embryological histories ; while, in some instances, 
a single lucky specimen may afford us, on a particular point, 
