ice-sheets did not cover?

Louis Figuier says:

"Such masses of ice could only have covered the earth when the
temperature of the air was lowered at least some degrees below zero.
But organic life is incompatible with such a temperature; and to this
cause must we attribute the disappearance of certain species of
animals and plants--in particular the rhinoceros and the
elephant--which, before this sudden and extraordinary cooling of the
globe, appeared to have limited themselves, in immense herds, to
Northern Europe, and chiefly to Siberia, where their remains have
been found in such prodigious quantities."[1]

But if the now temperate region of Europe and America was subject to
a degree of cold great enough to destroy these huge animals, then
there could not have been a tropical climate anywhere on the globe.
If the line of 35° or 40°, north and south, was several degrees below
zero, the equator must have been at least below the frost-point. And,
if so, how can we account for the survival,

[1. "The World before the Deluge," p. 462.]

{p. 33}

to our own time, of innumerable tropical plants that can not stand
for one instant the breath of frost, and whose fossilized remains are
found in the rocks prior to the Drift? As they lived through the
Glacial age, it could not have been a period of great and intense
cold. And this conclusion is in accordance with the results of the