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as the plants of the earlier periods are low in the scale of 
life, consisting of thallophytes and pteridophytes and plants 
of uncertain botanical determination, while those which 
appear in the successively later periods are of successively 
more complex types, represented by cycads, conifers and 
both monocotyledonous and dicotyledonous plants closely 
related to our living flora. 
The series of exhibits begins in the first case to the left as 
one enters the east wing of the basement. The sequence of 
the specimens in the wall cases corresponds to that of the 
floor cases. 
In the first floor-case may be seen representatives of Eozoic 
and Palaeozoic Time: Laurentian, Cambrian, Lower Sil- 
urian, Upper Silurian, Devonian, and Carboniferous Periods. 
At the north end are specimens of graphite of eozoic age 
and of anthracite and bituminous coal of carboniferous age, 
showing the transformation of vegetable matter into the ulti- 
mate condition of pure carbon in the form of graphite or 
“‘black lead” in the oldest rocks. Many of the specimens 
in this case, classed as algae, are of uncertain botanical 
relationship, as the structure of the primitive plants was not 
well adapted for preservation as fossils. For example, some 
organisms appear as mere filamentous strips of graphite in 
white limestone, without any trace of the original structure 
remaining, while others may be seen as casts and impressions 
which closely simulate in general appearance different parts 
of the sea-weeds now existing. In this series of problematic 
fossils are also included a number of forms at one time 
definitely classed as plants but now by some assumed to be of 
animal or inorganic origin; namely, Scolzthus, which may be 
caused by worm burrows; Phylops7s, which may be a coral; 
Plumalina, which may be a hydroid; Dendrophycus, which 
may be current-markings; and Drctyolites, which are most 
likely sun-cracks. All of these, however, have at one time 
or another been definitely regarded as the remains of marine 
plants and were originally so described and classified. 
In this case are also the remains of the earliest fern-plants 
