6 
with well known fossils, had not most of the specimens 
been too imperfect to admit of a close comparison."* Again, 
out of twenty genera of coal plants from Australia, thirteen 
are common to the coal-fields of Britain, and six are well 
known in the Oolitic coal deposits of Yorkshire. 
How near these appearances may approximate to, or what 
was the actual state of, the flora at such distant epochs, it 
is impossible now to tell, and as unwise to theorise from, 
as it is to argue, that because we have Cycadean plants 
and Tree Ferns embedded in our strata, we must have had, 
in remote ages, a tropical climate ; such inferences, however, 
are perfectly gratuitous, as founded upon inaccurate observa- 
tion. For as Dr. Lindley remarks, " That, as many of 
these supposed tropical plants are in reality destitute of 
living analogies, and, therefore, as we do not know what 
they were, we have no means of judging what kind of 
climate they required. Supposing, however, that some of 
the Lepidodendra were allied to the genus Araucaria, yet 
that fact does not afford any proof of a tropical climate ; 
for Araucaria Dombeyi now inhabits the cold mountains 
of Southern Chili, and is at this day uninjured in the 
severest of our English winters ; while Cunninghamia sinen- 
sis, and species of Callitris or Dacrydium, with which other 
remains of Lepidodendra may be compared, are found on 
the mountains of New Zealand and Van Diemen's Land, 
where they have anything but a temperate climate ; and 
Salisburia Adiantifolia, which would certainly be considered 
a tropical form of ConiferiaB if found in a fossil state only, 
is one of the hardiest of trees, and a native of the rigorous 
climate of Japan. The supposed succulent nature of such 
plants as Sigillaria, Favularia, &c, which would ally them 
to the Cactaceae and Euphorbiacese, although the majority 
of such plants are natives of hot countries, would afford 
* Travels in North America, vol. ii., p. 158. 
