80 The Presidential Address.
further reflect upon the vicissitudes to which fossiliferous
strata are and have been at all times exposed by denudation,
erosion, and metamorphism, it appears to me that there is
not much matter for marvel in this poverty of the geological
record, but rather that we should wonder at its comparative
richness. In fact the geological record, however imperfect it
may be, has furnished the very strongest evidence in favour
of the Darwinian theory, and since the year 1859 the progress
of Palaeontology has enabled many gaps between the most
diverse groups of animals to be filled up. What more distinct
in external form and mode of life than birds and reptiles ?
These two classes had, however, long been known to
anatomists to be structurally related, and on the principle of
evolution the existence of intermediate forms might have
been anticipated. In 1862, after Darwin had predicted the
existence of such connecting links,10 there was found in the
Solenhofen limestone of the Upper Jurassic series, in Bavaria,
the now well-known Archaeopteryae, an animal uniting the
characters both of birds and reptiles. Professor Huxley sub-
sequently pointed out that a family of extinct gigantic reptiles,
the Dinosauria of the Oolite and Cretaceous formations, pre-
sented certain distinctly avian characters. These discoveries
culminated, in 1875, in Professor Marsh's great find of
toothed birds, the Odontornithes of the Cretaceous beds of
Kansas,17 a discovery which, as Professor Huxley says,
"removed Mr. Darwin's proposition that 'many animal
forms of life have been utterly lost, through which the
early progenitors of birds were formerly connected with the
early progenitors of the other vertebrate classes,' from the
region of hypothesis to that of demonstrable fact."18 In a
similar manner the pedigree of the horse has been traced
back by Professor Marsh to the Eocene species of Eohippus,19
an animal about the size of a fox ; and the pedigrees of the
16 'Origin,' 1st ed., p. 431.
17 Vol. i., 'Memoirs of Peabody Museum of Yale College'; vol. vii.,
"Geological Exploration of the 40th Parallel."
18 " The Coming of Age of the 'Origin of Species,'" 'Nature,' May 6th,
1880, p. 3.
19 Amer. Jour. Sci., 1879.