a. 
VII “THE ORIGIN OF SPECIES” 239 
duce to us a multitude of extinct animals, the 
existence of which was previously hardly sus- 
pected; just as if zoologists were to become 
acquainted with a country, hitherto unknown, as 
rich in novel forms of life as Brazil or South 
_ Africa once were to Europeans. Indeed, the fossil 
fauna of the Western Territories of America bid 
fair to exceed in interest and importance all other 
known Tertiary deposits put together; and yet, 
with the exception of the case of the American — 
tertiaries, these investigations have extended over 
very limited areas; and, at Pikermi, were con- 
fined to an extremely small space. 
Such appear to me to be the chief events in the 
history of the progress of knowledge during the 
last twenty years, which account for the changed 
feeling with which the doctrine of evolution is at 
present regarded by those who have followed the 
advance of biological science, in respect of those 
problems which bear indirectly upon that doc- 
trine. 
But all this remains mere secondary evidence. 
It may remove dissent, but it does not compel 
assent. Primary and direct evidence in favour of 
evolution can be furnished only by paleontology. 
The geological record, so soon as it approaches 
completeness, must, when properly questioned, 
yield either an affirmative or a negative answer: 
if evolution has taken place, there will its mark 
