190 MH. C. IIEID ON TUE FLORA OF THE CROMER FOREST-RED. 
successive epochs. It is therefore evident that the collection 
and examination of these idants ought to throw much light 
on the origin of the living flora of Britain, though the origin 
of tliat flora must be carried still further back into the Pliocene 
Period. 
Ihese are the points of special botanical interest brought out by 
this study. But there are also difficult geological problems which 
an examination of the plants ought to assist in solving. We know 
that an epoch of intense cold — the Glacial Epoch — intervened 
between the Pliocene Period and the Period in which Ave are now 
living. This is generally recognised, though the extent to which 
the Arctic conditions affected the fauna and flora, and the southern 
limit of the intense cold, are still disputed points. 
A study of the fauna has shown that there was a sweeping 
extermination of the large highly specialized mammals j but that the 
more lowly organized orders, and the invertebrate animals, mostly 
survived.* The examination of the plants brings out this partial 
and local character of the change even more markedly, and it 
seems evident that the species driven out of the country by the 
cold of the Glacial Epoch, must have survived within a moderate 
distance of England. If the .intense cold had extended, as is 
sometimes suggested, far south of Britain, we should scarcely 
expect to find that most of the plants of the Pre-Glacial Cromer 
Eorest-bed have been able to re take their old province — Ave should 
rather expect to find numerous extinct forms among the fossils, 
and that those driven soutlnvard into Africa, or to the shores 
of the Mediterranean, had been replaced by a very different 
assemblage. 
In the endeavour to throw a little light on these questions, 
I have continued the collection and study of the plants since the 
official survey Avas finished in 1879. The results may perhaps 
seem .scarcely to repay the time and trouble needed for long 
journeys to Norfolk to obtain material, and for the devotion of 
evening after evening to the Avashing, picking out, and mounting 
of the seeds. Unfortunately there is seldom anything preserved 
but fruits and seeds — though these are much more satisfactory for 
determination than leaves. During December, 1881, a consider- 
* See also Eeid, ‘ Memoirs of the Geological Survey.’—" Geology of 
Cromer,” p. GO. 
