JjyelVs Principles of Geology. 181 



in the intermediate countries is against this idea. Why could 

 not they come from the countries bordering on China, of 

 which we know nothing ? 



None of the arguments adduced either from Cycadese, Equi- 

 setaceae, tree ferns, and arborescent Lycopodiaceae, p. 153 to 

 p. 155, appear to me to warrant the idea of an extremely hot 

 climate. Of Cycadeae we want the forms given, for this family 

 is now abundant at the Cape of Good Hope, and Cycas re- 

 voluta grows in Japan. So far as I have had occasions of 

 judging, tropical Equisetaceae are not larger than those of 

 cold climates, and what is curious, are never so abundant in 

 the tropics as in cold climates. Tree ferns in India are ex- 

 tra-tropical, and the species that equals the fossil size is found 

 in latitude 25°, at an elevation of 4,000 feet, which, if the 

 calculations of Humboldt can be applied to these parts of 

 Asia, would make the latitude of its site 35° N. ; and, what is 

 still more to the purpose, in the southern hemisphere they 

 reach to 45°. As for Lycopodiaceae, nothing approaching to 

 arborescent species are now found, and in India, even in the 

 most favourable places, the stature is but little greater than 

 that of European species. 



The explanation given of the Melville fossils p. 155, may 

 be received, provided no objections are found to the adop- 

 tion of the idea that tropical forms could not have existed 

 under the circumstances described. But although the fossils, 

 are of distinct species, they do not present any singularities 

 in structure, which we should expect in plants submitted 

 yearly to a night of three months. And it must be remem- 

 bered, that there is no instance of an unbranched monocoty- 

 ledonous plant being capable of hybernation, and as to the 

 English coal fields, there is perhaps no absolute reason for 

 insisting on a great degree of heat. The effect of latitude 

 is secondary, inasmuch as it depends upon the proportion 

 between land and sea, and the configuration and elevation 

 of the former. 



