166 THE MEDALS OF CREATION. Cuap. VI. 
the coniferous trees, whose mineralized trunks and branches, 
in a fragmentary state, are, for the most part, the only relics 
of these important tribes of the lost floras of the earlier ages 
of our planet.* 
The great value of these data will be shown in the sequel. 
The stems, fruit, and foliage, of Coniferze, occur in the 
various fossiliferous deposits, from those containing the 
earliest traces of terrestrial vegetation to the newest tertiary 
strata; anda large proportion of the petrified wood found 
in the British formations belongs to trees of this order. 
The presence of rows of ducts on the ligneous fibres, which 
is peculiar to this division of gymnosperms, as we have 
already explained (ante, p. 58), is so easily detected by 
microscopic examination, that the merest fragment of 
fossil coniferous wood retaining internal structure, may 
without difficulty be recognized. The number of rows, 
and the opposite or alternate arrangement of the areole, 
are characters which, in the living pines and firs, en- 
able us to refer the respective trees to European or exotic 
forms; but in the fossil coniferous wood, much diversity 
exists in other not less important poimts of structure, and 
for the successful cultivation of this department of fossil 
botany, works especially devoted to the subject must be 
consulted. To the English student, Mr. Witham’s beau- 
tiful volume, “ Observations on the Structure of Fossil 
Vegetables, Edinburgh, 1831,” will be found a valuable 
guide. 
* I know not a more delightful and instructive branch of science 
for the young and inquiring of both sexes, than this department of 
Fossil Botany, which the recent improvements in the microscope have 
rendered so accessible; and yet there are but few cultivators of fossil 
botany in England ! 
