460 PROFESSOR HEEE ON THE FOSSIL FLORA OF NORTH GREENLAND. 
been newly discovered do not affect the truth of this statement. Platanus Guillelrnce 
and Quercus Laharpii have certainly been only found in the Upper Miocene of 
Europe ; while Smilax grandifolia , Widdringtonia Helvetica , Dryandra acutiloba, Aspi- 
dium Eeerii , and Corylus insignis occur only in the Lower Miocene; and Sassafras 
Ferretianum , with Aspidium Meyeri and Liquidambar Furopceum , have been met with 
in both divisions. 
In conclusion I beg to offer a few remarks as to the amount of certainty in identifica- 
tion which the determination of fossil plants is able to afford us. We know that the 
flowers, fruit, and seeds are more important as characteristics than the leaves. There are 
many genera of which the leaves are very variable, and would consequently be likely to 
lead us astray if we trusted to them alone. However, many peculiarities as to the form 
and nervation of leaves are well known to be characteristic of certain genera, and can 
therefore afford us indications of great value for their recognition. Most fortunately in 
the case of fossil plants we are not always dependent on the leaves alone for purposes of 
identification. Of many plants we know other organs which, taken in connexion with 
the leaves, justify a determination as absolute as that of a living plant. If a species has 
been once thoroughly identified in this manner we are able to recognize it in other 
localities where the leaves alone are found. The same is true of living plants in many 
cases. We recognize at first glance a fir, a beech, a maple, &c. if we see the leaves only, 
without looking to the flowers or fruit. 
On the whole, then, the following are the grounds on which the determination of the 
plants belonging to the Miocene Flora of Greenland has been based respectively. 
I. Species identified by means of leaves, flowers, fruit, and seeds. 
Sequoia Langsdorfii, Castanea Ungeri, and Diospyros brachysepala. 
II. Species identified by means of leaves and fruit. 
Taxodium, Sequoia Couttsise, Sparganium, Myrica, Populus Richards oni, P. 
Arctica, Ostrya, Corylus M‘Quarrii, Menyanthes, Magnolia, and Paliurus. 
III. Species identified by means of leaves and seeds. 
Vitis and Prunus. 
Accordingly the leaves and organs of fructification of IT species have been described*. 
IV. Ten species are only represented in Greenland by their leaves, while their fruit, 
and in some cases their flowers and seeds, have been found elsewhere. 
Glyptostrobus europseus, Pinus polaris, Widdringtonia helvetica, Liquidambar 
europseum, Planer a Ungeri, Platanus aceroides, Andromeda protogsea, Carpinus 
grandis, Juglans acuminata, Populus Zaddachi, and Quercus furcinervis. 
Y . The remainder of the Phanerograms is only known to us by means of their leaves. 
The leaves of many of the species have, however, such well-marked characteristics, that 
their generic determination may be considered as complete. These are 
Salisburea adiantoides, Smilax grandifolia, Salix Rseana, S. Gronlandica, Alnus 
nostratum, Fagus Deucalionis, Quercus Greenlandica, Q. Olafseni, Q. Lyellii, Q. 
* Notice of the fruits of Quercus and Fagus is omitted in default of complete identification. 
