numerous class of Echinoderms presents three; and the Crustacea two,
such orders, though none of these come down later than the Paleozoic
age. Lastly, the Reptilia present the extraordinary and exceptional
phenomenon of as many extinct as existing orders, if not more; the four
mentioned maintaining their existence from the Lias to the Chalk
inclusive.

Some years ago one of your Secretaries pointed out another kind of
positive paleontologic evidence tending towards the same
conclusion--afforded by the existence of what he termed "persistent
types" of vegetable and of animal life.* He stated, on the authority of
Dr. Hooker, that there are Carboniferous plants which appear to be
generically identical with some now living; that the cone of the
Oolitic 'Araucaria' is hardly distinguishable from that of an existing
species; that a true 'Pinus' appears in the Purbecks, and a 'Juglans' in
the Chalk; while, from the Bagshot Sands, a 'Banksia', the wood of
which is not distinguishable from that of species now living in
Australia, had been obtained.

[footnote] *See the abstract of a Lecture "On the Persistent
Types of Animal Life," in the 'Notices of the Meetings of
the Royal Institution of Great Britain'.--June 3, 1859,
vol. iii. p. 151.

Turning to the animal kingdom, he affirmed the tabulate corals of the
Silurian rocks to be wonderfully like those which now exist; while even
the families of the Aporosa were all represented in the older Mesozoic
rocks.

Among the Molluska similar facts were adduced. Let it be borne in mind