for many of the facts, although I hold migration myself, and always have 
clone so. Take the Ammonites : we find them for the first time in the car- 
boniferous beds ; if I am told, “ That is not their first appearance : it is a case 
of migration from some other area, as the Devonian ” ; or, “ They occur in the 
Silurian beds of New Zealand,” it is open to me to say that that is not their 
first appearance either, and that they have migrated from somewhere else. But 
it comes to an absolute certainty that, in the aggregate, we must know the first 
appearance of a great many forms, although we cannot make a positive asser- 
tion as to individual cases. As to the existence of pre-Laurentian rocks, that 
is a matter of opinion ; such may have existed, but opinion is not yet definitely 
settled as to the existence of life, even in the Laurentian deposits ; and as it 
is quite possible, and indeed probable, that these were all formed out of 
igneous rocks, we have no right to found any argument on the supposed 
existence of fossiliferous rocks prior to the Laurentian ; there may have been 
such rocks, but we know nothing of them. As to the variation of the lower 
and higher types of life, I should be quite inclined to agree with Mr. 
Henslow, that there is a great difference, and I think it quite probable that 
in very many cases the variation is a quick one, and is effected per saltum : 
we know this is sometimes the case among living animals, — Japanned 
peacocks, for instance, have been produced by a sport. — This is more likely 
to occur in the case of the higher, than in the case of the lower animals. 
With regard to the extinction of Ammonites, that is a rather unfortunate 
instance to take, because there is such an enormous break in all parts of the 
world between the highest Cretaceous rocks and the lowest Tertiary rocks, 
that we do not know what became of those Cephalopods, nor of any Tetra- 
branchiates except the Nautili. It is almost certain that we shall find rocks, 
somewhere, intermediate in age between the lower Tertiaries and the upper 
Cretaceous, and there we may find Ammonites ; but this is at present con- 
jectural. Finally, with regard to the question as to the origin of species, I 
had hoped that I had distinctly expressed my opinion that evolution does 
occur, and that evolution is an operating cause in the modification and pro- 
duction of species. The remark that variation is bounded by definite limits 
is, all the same, quite true, though you admit evolution. When I say that 
variation is not indefinite, I am quite prepared to believe that the horse and 
the donkey have proceeded from a common ancestor, but that does not bind 
me to suppose that they have descended from an oyster (laughter). Variation 
must stop somewhere (cheers). 
The meeting was then adjourned. 
NOTE. 
Principal Dawson,. F.R.S., in his 1874 Annual Address, as Presi- 
dent of the Natural History (Society of Montreal, made some remarks, the 
insertion of which may not bo deemed out of place at the close of this 
discussion. After alluding to the earlier elevation of that coast, he 
continued “ We know that the eastern coast of America has in modern 
