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soundings of the bottom of the Atlantic； and although； as we must all
regret； up to the present time that project has not succeeded； we have
the satisfaction of knowing that it yielded some most remarkable results
to science。 The Atlantic Ocean had to be sounded right across； to
depths of several miles in some places； and the nature of its bottom
was carefully ascertained。 Well； now； a space of about 1；000 miles
wide from east to west； and I do not exactly know how many from north to
south； but at any rate 600 or 700 miles； was carefully examined； and it
was found that over the whole of that immense area an excessively fine
chalky mud is being deposited； and this deposit is entirely made up of
animals whose hard parts are deposited in this part of the ocean； and
are doubtless gradually acquiring solidity and becoming metamorphosed
into a chalky limestone。 Thus； you see； it is quite possible in this
way to preserve unmistakable records of animal and vegetable life。
Whenever the sea…bottom； by some of those undulations of the earth's
crust that I have referred to； becomes upheaved； and sections or
borings are made； or pits are dug； then we become able to examine the
contents and constituents of these ancient sea…bottoms； and find out
what manner of animals lived at that period。
Now it is a very important consideration in its bearing on the
completeness of the record； to inquire how far the remains contained in
these fossiliferous limestones are able to convey anything like an
accurate or complete account of the animals which were in existence at
the time of its formation。 Upon that point we can form a very clear
judgment； and one in which there is no possible room for any mistake。
There are of course a great number of animalssuch as jelly…fishes；
and other animalswithout any hard parts； of which we cannot
reasonably expect to find any traces whatever： there is nothing of them
to preserve。 Within a very short time； you will have noticed； after
they are removed from the water； they dry up to a mere nothing；
certainly they are not of a nature to leave any very visible traces of
their existence on such bodies as chalk or mud。 Then again； look at
land animals； it is； as I have said； a very uncommon thing to find a
land animal entire after death。 Insects and other carnivorous animals
very speedily pull them to pieces； putrefaction takes place； and so； out
of the hundreds of thousands that are known to die every year； it is
the rarest thing in the world to see one imbedded in such a way that
its remains would be preserved for a lengthened period。 Not only is
this the case； but even when animal remains have been safely imbedded；
certain natural agents may wholly destroy and remove them。
Almost all the hard parts of animalsthe bones and so onare composed
chiefly of phosphate of lime and carbonate of lime。 Some years ago； I
had to make an inquiry into the nature of some very curious fossils
sent to me from the North of Scotland。 Fossils are usually hard bony
structures that have become imbedded in the way I have described； and
have gradually acquired the nature and solidity of the body with which
they are associated； but in this case I had a series of 'holes' in some
pieces of rock； and nothing else。 Those holes； however； had a certain
definite shape about them； and when I got a skilful workman to make
castings of the interior of these holes； I found that they were the
impressions of the joints of a backbone and of the armour of a great
reptile； twelve or more feet long。 This great beast had died and got
buried in the sand； the sand had gradually hardened over the bones； but
remained porous。 Water had trickled through it； and that water being
probably charged with a superfluity of carbonic acid； had dissolved all
the phosphate and carbonate of lime； and the bones themselves had thus
decayed and entirely disappeared； but as the sandstone happened to have
consolidated by that time； the precise shape of the bones was retained。
If that sandstone had remained soft a little longer； we should have
known nothing whatsoever of the existence of the reptile whose bones it
had encased。
How certain it is that a vast number of animals which have existed at
one period on this earth have entirely perished； and left no trace
whatever of their forms； may be proved to you by other considerations。
There are large tracts of sandstone in various parts of the world； in
which nobody has yet found anything but footsteps。 Not a bone of any
description； but an enormous number of traces of footsteps。 There is
no question about them。 There is a whole valley in Connecticut covered
with these footsteps； and not a single fragment of the animals which
made them has yet been found。 Let me mention another case while upon
that matter； which is even more surprising than those to which I have
yet referred。 There is a limestone formation near Oxford； at a place
called Stonesfield； which has yielded the remains of certain very
interesting mammalian animals； and up to this time； if I recollect
rightly； there have been found seven specimens of its lower jaws； and
not a bit of anything else； neither limb…bones nor skull； or any part
whatever； not a fragment of the whole system！ Of course； it would be
preposterous to imagine that the beasts had nothing else but a lower
jaw！ The probability is； as Dr。 Buckland showed； as the result of his
observations on dead dogs in the river Thames； that the lower jaw； not
being secured by very firm ligaments to the bones of the head； and
being a weighty affair； would easily be knocked off； or might drop away
from the body as it floated in water in a state of decomposition。 The
jaw would thus be deposited immediately； while the rest of the body
would float and drift away altogether； ultimately reaching the sea； and
perhaps becoming destroyed。 The jaw becomes covered up and preserved in
the river silt； and thus it comes that we have such a curious
circumstance as that of the lower jaws in the Stonesfield slates。 So
that； you see； faulty as these layers of stone in the earth's crust
are； defective as they necessarily are as a record； the account of
contemporaneous vital phenomena presented by them is； by the necessity
of the case； infinitely more defective and fragmentary。
It was necessary that I should put all this very strongly before you；
because； otherwise； you might have been led to think differently of the
completeness of our knowledge by the next facts I shall state to you。
The researches of the last three…quarters of a century have； in truth；
revealed a wonderful richness of organic life in those rocks。 Certainly
not fewer than thirty or forty thousand different species of fossils
have been discovered。 You have no more ground for doubting that these
creatures really lived and died at or near the places in which we find
them than you have for like scepticism about a shell on the sea…shore。
The evidence is as good in the one case as in the other。
Our next business is to look at the general character of these fossil
remains； and it is a subject which it will be requisite to consider
carefully； and the first point for us is to examine how much the
extinct 'Flora' and 'Fauna' as a 'whole'disregarding altogether the
'succession' of their constituents； of which I shall speak
afterwardsdiffer from the 'Flora' and 'Fauna' of the present
day；how far they differ in what we 'do' know about them； leaving
altogether out of consideration speculations based upon what we 'do
not' know。
I strongly imagine that if it were not for the peculiar appearance that
fossilised animals have； any of you might readily walk through a museum
which contains fossil remains mixed up with those of the present forms
of life； and I doubt very much whether your uninstructed eyes would
lead you to see any vast or wonderful difference between the two。 If
you looked closely； you would notice； in the first place； a great many
things very like animals with which you are acquainted now： you would
see differences of shape and proportion； but on the whole a close
similarity。
I explained what I meant by ORDERS the other day； when I described