Reviews—The Life and Works of Prof. Oswald Heer. 279 
number of ingenious conclusions which Heer has drawn from the 
presence of these creatures in the rocks—conclusions which could 
only have been arrived at by one who was thoroughly familiar with 
the habits of existing forms. 
Dr. Schréter devotes several chapters to the most important part 
of Heer’s life-work—namely, his contributions to fossil botany. 
After passing in review the work done in this branch of science 
before Heer contributed to it, he proceeds at once to the considera- 
tion of the important question as to the reliability of the determina- 
tions from dicotyledonous leaves. It has been generally supposed 
that Heer was himself satisfied as to the validity of determinations 
thus based; but, as Prof. Schréter points out, this is by no means the 
case. Heer has thus expressed his views on the point: “ In those 
instances, where the form of the leaves and their nervation are very 
characteristic, we may, at least with great probability, determine 
the plant from them ; in other cases, its systematic position must be 
regarded as doubtful until other portions of the plant have been 
discovered, by means of which the characters drawn from the leaves 
are corroborated. Leaves of this latter category are of little value 
from a systematic point of view, but they may, notwithstanding, be 
of great service in the determination of the geological horizon in 
which they occur. The systematic position of Myrica dryandrefolia, 
Brongniart, was thus for a long time doubtful. Brongniart himself 
referred the leaves to Comptonia, Ettingshausen to Dryandra, whilst 
Saporta was able at last to show that Brongniart’s opinion was correct. 
But although it was for a long time doubtful whether the leaves 
belonged to Myricacee or to the Proteacee, they nevertheless did 
good service as characteristic fossils.” 
Dr. Schréter is quite right in stating that it is unfortunate for the 
credit of phytopaleontology that names must be given even to those 
leaves of which the systematic position cannot be ascertained. The 
mischief would, however, to a certain extent, be avoided by the 
adoption of the method proposed by the reviewer, that no fossil leaf 
from strata older than the Pliocene should be placed under an exist- 
ing genus unless its generic relationship is sufficiently proved by 
other evidence, in addition to that of the leaf itself. When this 
cannot be shown, the leaf should either be given an independent 
generic name, such as Credneria, Dewalquea, Protophyllum, etc., or a 
name compounded of an existing genus with the suffix phyllum. A 
name of this character would not exclude the idea that the leaf in 
question might belong to the existing genus, it would only indicate 
that its congeneric identity had not been proved. If all fossil 
dicotyledonous genera were revised on this system, we should find 
that most of the Cretaceous forms would be brought under Magnolv- 
phyllum, Populiphyllum, Lauriphyllum, Platanophyllum, etc., instead of 
Magnolia, Populus, Laurus, and Platanus. Of Tertiary plants, a 
greater percentage would be brought within existing genera, but 
others would have to retain the provisional suffix phyllum. It might 
even happen that both generic names could be used for different 
species from the same deposits, as, for example, Acer arcticum and 
