THE PRE-GLACIAL FLORA OF BRITAIN. 291 
General Conclusions. 
This revision nearly doubles the number of plants recorded from British 
pre-Glacial deposits, for it includes 147 species. We have also various seeds 
and fruits in а perfectly determinable state, but belonging either to extinct 
forms, or more probably in the main to British or erotic species not repre- 
sented in our recent collection. The determination of these is a very slow 
process ; for a seed so peculiarly sculptured as to be readily determinable, 
if we happen to know the recent form, may be so wanting in generic or 
broader characters as to give по clue to guide us in our search. We have 
not thought it advisable to figure these incert sedis, unless we could make a 
definite suggestion as to the families or genera to which they belong, or could 
draw up a clear botanical description. This is often impossible without 
destroying a unique specimen in order to examine its internal characters. 
The mention of internal characters as applied to specimens of which 
nothing now remains but the testa or endocarp may seem absurd. It must 
not be forgotten, however, that in botany, as in zoology, soft parts impress 
their forms on indestructible hard parts, and convolutions of the embryo or 
'aseular markings may be as well studied from the inside of the testa as in 
the interior of the skull of some extinct race of man. The illustration of the 
interior of the fruit of Ceratophyllum demersum (Pl. 14. fig. 143) will indicate 
how perfect may be this preservation. 
Our pre-Glacial flora is found in a series of alluvial and estuarine deposits, 
which underlie the boulder-clay and stretch for nearly fifty miles along the 
Norfolk and Suffolk coasts, from Sherringham to Pakefield. Тһе deposits 
consist of estuarine muds and gravels, apparently brought down by the 
Rhine, which at that period, after receiving numerous large tributaries—now 
separate rivers—seems to have flowed across the present bed of the North Sea. 
It probably entered the sea somewhere near Cromer. Unfortunately the 
estuarine deposits are very stony, contain ferruginous concretions, and show 
few drift fruits ; they have therefore not yet been properly examined for 
plants. It is in these, if anywhere, that we should expect to discover the 
dry-soil exotie forms lately found higher up the Rhine, at Tegelen, in 
Limburg. At that place an ancient Rhine alluvium, somewhat older than 
the Cromer Forest-bed, contains a large flora, the plants showing drier 
conditions and slightly more southern affinities. The Tegelen list includes 
Magnolia Kobus, Juglans, Pterocarya caucasica, Vitis vinifera, several South 
European plants, and new species of Huryale and Stratiotes. It also contains 
a number of dry-soil North European plants, which help to complete the 
imperfect picture of the pre-Glacial flora left by our British fossils *. 
The plants of our British pre-Glacial deposits, unfortunately, have been 
collected almost exclusively from the alluvium of small tributary channels, 
* The Tegelen flora has been described by us in a communication sent to the Academy of 
Sciences at Amsterdam: Versl. К. Akad. Wetens. 2e Sect. xiii. n. 6 (1907). 
