SECONDARY ROCKS. 
87 
Coniferae .... 10 species. 
Indeterminate . . 60 " 
300 species. 
These facts seem to show conclusively that the 
flora of the epoch of the coal formations was very 
different from that of the present day, as the vegeta- 
ble families which are now the most numerous 
were then wholly wanting, and those which are 
now comparatively rare were then numerous. Ve- 
getables also, which are now mere herbs, then at- 
tained the size of large trees ; as, for example, the 
ferns, which, though they now attain the height of 
but a few feet at the most, then grew as large as 
our tallest trees. This, among other facts, has 
led geologists to believe that the climate of the 
surface of the earth at that period was excessively 
hot, and, not only so, but uniform in every latitude, 
as the fossil remains of the coal formations of ev- 
ery latitude are the same. But, at the present 
time, every latitude, and, indeed, every different de- 
gree of elevation, has its own species of plants. 
It is a remarkable circumstance also, that marine 
remains have rarely been detected in coal-beds, 
although they abound in carboniferous limestone, 
which lies below the coal measures ; which circum- 
stance, if it does not prove the deposite of coal to 
have been effected in fresh water, yet shows that 
there was something which prevented the presence 
of marine animals. De la Beche states that the 
Yorkshire coal-beds in England contain the remains 
of ammonites and pectines, and that the fossils of the 
carboniferous limestone and coal measures are de- 
tected in the millstone grit ; in other words, that 
there was an alternation of terrestrial with marine 
remains. The same fact has lately been noticed in 
Germany. 
This accumulation of vegetable matter, at a re- 
mote period in the history of the world, for the use 
