460 Notices of Memoirs—Prof. Boyd Dawkins’s Address. 
much we have grown since 1864, when evolution was under discus- 
sion, and when biological, physical, and geological laboratories could 
scarcely be said to have existed in this country. Truly may the 
scientific youth of to-day make the boast 
“Huets mev ratépwv pméy? dmetvoves evyoped’ etvar— 
‘“We are much better off than our fathers were,” while we, the 
fathers, have the poor consolation of knowing that when they are 
fathers, their children will say the same of them. There is reason to 
suppose that our science will advance more swiftly in the future than 
it has in the past, because it has more delicate and precise methods 
of research than it ever had before, and because its votaries are more 
numerous than they ever were. 
In 1864 the attention of geologists was mainly given to the in- 
vestigations of the later stages of the Tertiary period. The bent of 
my pursuits inclines me to revert to this portion of geological inquiry, 
and to discuss certain points which have arisen during the last few 
years in connection with the classificatory value of fossils, and the 
mode in which they may be best used for the co-ordination of strata 
in various parts of the world. 
The principle of homotaxy, first clearly defined by Professor 
Huxley, has been fully accepted as a guiding principle in place of 
synchronism or contemporaneity, and the fact of certain groups of 
plants and animals succeeding one another in a definite order, in 
countries remote from each other, is no longer taken to imply that 
each was living in the various regions at the same time, but rather, 
unless there be evidence to the contrary, that they were not. While, 
however, there is a universal agreement on this point among 
geologists, the classificatory value of the various divisions of the 
vegetable and animal kingdoms is still under discussion, and, as has 
been very well put by my predecessor in this chair at Montreal, 
sometimes the evidence of one class of organic remains points in one 
direction, while the evidence of another class points in another and 
wholly different direction as to the geological horizon of the same 
rocks. The Flora, put into the witness-box by the botanist, says one 
thing, while the Mollusca or the Vertebrata say another thing in the 
hands of their respective counsel. There seems to be a tacit assump- 
tion that the various divisions of the organic world present the same 
amount of variation in the rocks, and that consequently the evidence 
of every part of it is of equal value. 
It will not be unprofitable to devote a few minutes to this question, 
premising that each case must be decided on its own merits, without 
prejudice, and that the whole of the evidence of the flora and fauna 
must be considered. We will take the flora first. 
The cryptogamic flora of the later Primary rocks shows but slight 
evidence of change. The forests of Britain and of Europe generally, 
and of North America, were composed practically of the same 
elements—Sigillaria, Calamites, and Conifers allied to the Ginkho— 
throughout the whole of the Carboniferous (16,336 feet in thickness 
in Lancashire and Yorkshire) and Devonian rocks, and do not present 
greater differences than those which are to be seen in the existing 
