Boo Geological Extinction and [ January, 
species and genera. The Eocene fauna was richer than the Mio- 
cene, the Miocene than the Pliocene, and the Pliocene than the 
modern fauna.” There is certainly a significant parallelism be- 
tween the widespread changes in the physical geography of North 
America, the differentiation of climates and of faunal areas, and 
the increasing extinction of life. | 
The West Indies meanwhile were the scene of notable changes 
in the distribution of land and sea. From being much larger, 
and in some cases connected perhaps with South America, they be- 
came submerged, Cope has described the fossil remains found ina 
cave on the Island of Anguilla. Out of twelve species of mam- 
mals, seven are extinct and several were chinchillas of large 
size. 
About the shores of the Mediterranean there were remarkable 
changes in the relations of land and sea. The species of dwarf 
and other elephants whose bones have been discovered on the Is- 
land of Malta, show that within recent times that island must 
have been connected with the main African continent. 
In the old world, simultaneously with the mountain-building of 4 
America, the Alps during the later Pliocene attained their present 
proportions ; the Himalayas rose to their present heights; the 
continents of Asia, with Europe, and of Africa assumed their pres- 
ent outlines. 
The extent and nature of the changes which took place late in i 
the Pliocene in the physical geography of the globe were without __ 
doubt much greater than at any previous time in the history of 
our planet. While the present coast lines were being established 
volcanic agencies were widespread and powerful, and over what 
were then regions of intense volcanic activity are to be now seen 
but the dyingsembers of subterranean fires. 
The long, quiet preparatory eons of the Mesozoic and early 
Tertiary, were succeeded by a crisis in geological history, just as _ 
the comparative quiet of the Paleozoic age terminated in the — 
widespread disturbances which took place at the end of the Coal _ 
period. 
If we glance back through the geological ages we shall see _ 
that there were cases of the comparatively rapid extinction of 
types or whole groups of animals. The more remarkable were 
the extinction of the trilobites and ammonites, 
PES 
; bese Darwin remarks: 
“The extermination of whole groups, as of ammonites toward — 
