ved from it in America by only
one."[11]

Professor Agassiz has expressed opinions of the same character, adducing
the present existence in America of several forms of animals, which are
known in this hemisphere only in a fossil state.[12]

I cannot refrain from adding the following combination of fact and
speculation, from the pen of an accomplished traveller in Mexico. It
opens up a new train of ideas:--

"Some time before our visit, a number of workmen were employed on the
neighbouring estate of Chapingo, to excavate a canal over that part of
the plain from which the waters have gradually retired during the last
three centuries. At four feet below the surface, they reached an ancient
causeway, of the existence of which there was of course not the most
remote suspicion. The cedar piles, by which the sides were supported,
were still sound at heart. Three feet below the edge of this ancient
work, in what may have been the very ditch, they struck upon the entire
skeleton of a Mastodon, embedded in the blue clay. Many of the most
valuable bones were lost by the careless manner in which they were
extricated; others were ground to powder on their conveyance to the
capital, but sufficient remained to prove that the animal had been of
great size. My informant measured the diameter [_qu._ circumference?]
of the tusk, and found it to be eighteen inches.

"Though I should be very glad to take shelter under the convenient
_Quien sabe_? the use of which I have suggested to you, I could not
avoid, at the time I was in Mexico, putting my isolated facts together,
and feeling inclined to believe that this country had not only been
inhabited in extremely remote times, when the valley bore a very
different aspect from that which it now exhibits, or which tradition
gives it, but that the extinct race of enormous animals, whose remains
would seem, in the instance I have cited, to be coeval with the undated
works of man, may have been subjected to his will, and made
instrumental, by the application of their gigantic force, to the
transport of those vast masses of sculptured and chiselled rock which we
marvel to see lying in positions so far removed from their natural site.

"The existence of these ancient paved causeways also, not only from
their solid construction over the flat and low plains of the valley, but
as they may be traced running for miles over the dry table-land and the
mountains, appears to me to lend plausibility to the