Surveys of the future, for whom such grand discoveries may in 
other countries be reserved. 
It would bo as unnecessary as impossible to enumerate all the 
considerations which have been or might be urged in illustration of 
the imperfection of the geological record ; doubtless many of them 
are familiar to you. Perhaps, however, a rapid glance over the 
actual state of our collection of mammalian fossils, up to the time 
of those deposits, in studying which we find ourselves in the 
presence of forms which naturalists now, and with reason, regard 
as the ancestors of living animals, may be interesting, as shewing, 
not theoretically what geology might be expected to furnish, 
but actually what she has, up to the present time, given us. 
We know that mammifers existed in Europe as far back as the 
time of the deposition of the Kinetic beds, which are considered by 
some geologists to belong to the Triassic, by others to the Liassic 
series. These deposits, which average about 50 feet in thickness, 
extend according to Mr. II. B. Woodward, from Redcar on the 
Yorkshire coast, to Lyme Regis in Dorsetshire. Mr. W. Boyd 
Dawkins has discovered in them a single molar of a small mammal, 
supposed to be marsupial ( Microlestes), of which genus Mr. Charles 
Moore had previously obtained, by searching through three cart- 
loads of clay, taken from a fissure in the mountain limestone at 
Frome, in Somersetshire, twenty-nine specimens of teeth. That 
this annual was not of local occurrence is proved by the fact that 
two similar teeth have been found in the neighbourhood of Stuttgart 
in Wurtombcrg, more than 500 miles distant. All the information 
we possess as to the mammalian life of the Rhcetic period i3 
comprised in this handful of teeth. 
Following the geological history, we may pass over the lower, 
middle, and upper Lias, representing an enormous period of time, 
and having a maximum thickness of something like 1500 feet, 
without finding any trace of mammalian remains. We may in 
like manner search unsuccessfully the greater part of the lower 
Oolitic strata, until at the base of the great Oolite, we reach the 
Stonesfield slate. Truth, it has been said, lies at the bottom of a 
well : our knowledge of the Stonesfield slate quadrupeds has been 
