s of Swainson's estimate,
the one thousand one hundred and forty-nine mammals of Charles
Bonaparte's estimate, the one thousand two hundred and thirty mammals of
Winding's estimate, and the one thousand five hundred mammals of Oken's
estimate. In the first edition of the admirable "Physical Atlas" of
Johnston (published in 1848) there are one thousand six hundred and
twenty-six different species of mammals enumerated; and in the second
edition (published in 1856), one thousand six hundred and fifty-eight
species. And to this very extraordinary advance on the eighty-nine
mammals of Raleigh, and the two hundred mammals of Buffon, we must add
the six thousand two hundred and sixty-six birds of Lesson, and the six
hundred and fifty-seven reptiles of Charles Bonaparte; or at
least,--subtracting the sea snakes, and perhaps the turtles, as fitted
to live outside the ark,--his six hundred and _forty-two_ reptiles.[29]

Such is the number of the known vertebrates, exclusive of the fishes,
with which in this question we have now to deal. Still, however, there
are a few lingering theologians, some of them very intelligent men, who
continue to regard the ark as quite big enough for them all. Dr.
Hamilton of Mobile, for instance, after fairly stating Swainson's
estimate, namely, one thousand mammalia, six thousand birds, and one
thousand five hundred reptiles and amphibiae, goes on to say, that "it
must not be forgotten, that of all these, the vastly greater proportion
are small; and that numbers of them could be placed together in the same
compartment of the ark." This, however, permit me to say with all
respect, is not meeting the real difficulty. No doubt many of the birds
are small,--many of the reptiles are small,--many even of the mammals
are small,--many small animals were known in the days of Raleigh, and
a much greater number of small animals are known now; but the question
proper to the case seems to be, What proportions do both the large
and the small animals now known bear to the large and small animals
known in the days of Raleigh or Buffon; and how much additional
accommodation-room would they require during their supposed voyage of a
twelvemonth? There are two different ways in which the list of the
known animals has been increased, especially of the known mammals. They
have been increased in a certain appreciable proportion by _discovery_;
and as discovery has been made chiefly in islands,--for the great
continents h