41 
Samuel Baker gives us. The place was comparatively clear a few years ago, 
but now it is a matter of the greatest difficulty to force a passage at all, after 
centuries of unobstructed navigation. As to the coral reefs, the different 
quantity of lime at different depths in the water has a most important 
bearing on the question : the speed of growth must depend on the amount 
of carbonate of lime which it is possible for the builders to get. But 
this point is little understood at present. There are different depths of 
the sea where the processes are completely reversed. It is also a question 
whether the coral began near the surface on a sinking bottom. Before we 
can decide time in this manner, we must discover whether what is going on 
has been going on at a constant rate, else we might as well try to catch a 
train with a watch which had no balance-spring. 
Rev. G. Henslow. — There are several things which one would feel 
inclined to talk about, but time passes, and the hour is getting late. It is 
interesting to see that we appear to be returning, to some extent at least, 
to the cataclysmic theory of former geologists, and to which Mr. Prestwich 
also appears to be coming round. No doubt the “ uniformitarian” processes 
are going on to a large extent, but whether we are to abandon the cata- 
clysmic views entirely is quite another thing. Mr. Prestwich refers to the 
glacial theory, as an instance of the arrangement of the globe for the benefit 
of man. That is a teleological idea, which had never occurred to me before, 
and it is certainly worthy of our consideration ; but he says we have now 
a uniform condition without cataclysms, and he contends that this is due 
to the glaciation of the previous period. With reference to the antiquity 
of man himself, I see no objection to the notion of his having lived in the 
pliocene or pre-glacial epoch. We know the flora of this country was then 
identical with what we have now, as far, at least, as the Cromer Forest and 
lignite beds show ; and the climatal conditions of their existence must 
have been much the same as now. But in all the gravels where man’s 
remains have been detected, they are either lying in depressions scraped 
out of the “ glacial drift ” itself, as at Bedford ; or else are from obvious 
reasons post-glacial. Yet that man might have existed before that time 
cannot be gainsaid. If the idea suggested by Mr. Belt, in his book on 
Nicaragua, should be confirmed, it would be very interesting to know that 
man must have existed before the glacial epoch. Whether, however, he 
lived during the Miocene epoch is another matter. I myself think not, 
though some, but doubtful, evidence has been thought to have been found ; 
for we know from examining the animals of that period, that not only is 
there not a single Miocene vertebrate species now living, but that all existing 
mammalian forms have been developed since that epoch ; thus, if we take 
the horse as it now is, the genus equus is not known at all in the 
Miocene period, but its ancestral representative, the hipparion, is abundant. 
If the horse has come from the hipparion, and both the civet and hyena 
of to-day differentiated from the ictitherium, then man, by analogy, would 
not be the same now as he would have been then ; i.e. on the imaginary 
