310 DR. J. D. HOOKER'S PRESIDENTIAL ADDRESS 
member of the existing family of Tetas, which eontained previously but 
one genus, that of the common Mare's-tails of our river-banks and woods; as 
also that nearly a dozen other genera of coal-measure plants may be referred 
genera now 
ways doubtful; but the value of these positive identifications is none the less 
on these accounts. It may hereafter prove of some significance that these Ca- 
lamites, which in the coal epoch assumed gigantic proportions, and presented 
multitudinous forms and very varied organs of growth, are now represented by 
but one genus, differing most remarkably from its prototype in size, and the 
simplicity and uniformity of its vegetable organs. Passing to the Tertiary flora, 
bours of Count Saperte in France, of Gaudin and Strozzi, and of Masso- 
longha in Italy, as oy asain in America, and above all, of Heer in Switzer- 
land, have within the last ten years accumulated a vast number of species of 
ossil plants ; and if the rs tuli of the affinities of the majority are de- 
pendible, they prove the persistence throughout the Tertiary strata of eqs: 
itoring families and | genera, and Mie mu of — than these. Here, how 
Almost the only wel 
[x] 
EM 4 gre RT S 3.4 in. ti 
tl f the vast majority of those Tertiary 
plants are their mutilated leaves, and, unlike the bones of vertebrate anim mals 
and the shells of mollusks, the leaves of ao plants are extremely vari- 
able in all their characters. Furthermore, the leaves of plants of different 
natural families, and of different ir ben one another to such a degree, 
that in the ease of recent plants every botanist regards these organs as most 
flowers, few traces are to be found in the fossils, and yet it is from tuem exclu- 
sively that the position of a recent plant in the vegetable kingdom can be cer- 
tifi An instructive instance of over-reliance on leaves, and perhaps, too, on 
preconceived ideas, happened not long ago to a paleontologist of such distin- 
guished merit that his reputation cannot suffer from an allusion to it. In the 
eality, he referred three associated impressions of fossil leaves to three genera, 
belonging to as many different families of plants, and was shoe helped to = 
which they were deposit ted. A subsequent chine, Bre was a botanist; but 
not a paleontologist, declares these three supposed genera to be the three leaf- 
grows on the spot. Which of the two is right, I do not say ; the fact shows 
to what opposite conclusions different observers of the same fossil materials 
may be led. If, however, much is uncertain, all is not so, and the science has 
of late made sure and steady progress, and developed really grand results. 
Heer’s labours on kt Mioene and Pliocene floras especially are of the highest 
value and interest. conclusions regarding the flora of the Bovey Tracey 
coal-beds (for the Bina of which, in a form worthy of their value and of 
their author's merit, we are indebted to the wise liberality of Miss Burdett 
Sheth CET EIU As ere PED. T 
ERR ee TO 
