Mil. GOURLDS on the Fossil Plants in the Glasgow Geological Museum, 111 



bined influence of heat and a humid atmosphere, in which respect I 

 need hardly remind you that the arid sands and sterile rocks of 

 Africa are not to bo compared to the hills and dales of more tem- 

 perate, but also more humid regions.* It has been suggested that in 

 former ages the waters were more extensively distributed over tho 

 surface of tho globe, and the moist atmosphere which would result, 

 combined with a temperature much less than that of the torrid zone, 

 would suffice to produce an abundant and rapid development of vege- 

 table forms, without the aid of larger quantities of carbonic acid than 

 we find in our present atmosphere. We do not know what kind of 

 plants composed the great mass of the coal strata : equally ignorant 

 are we of tho capability which such plants as the lopidodendra or 

 sigillaria3 possessed of flourishing in a temperate climate. The occa- 

 sional occurrence of an arborescent fern, or of a palm — for they are 

 both extremely rare in the coal measures — does not furnish sufficient 

 evidence of a hot climate, ^sinco such rivers as the Amazon or the 

 Mississippi are probably at this moment depositing in their estuaries 

 immense quantities of plants which may have been borne down in 

 their waters for four or five thousand miles. The vast rivers of Siberia, 

 two to three thousand miles in length, and the Mackenzie river of 

 North America, carry down pines and other trees, with their roots 

 attached, for many hundred miles, finally stratifying them in the Arctic 

 Sea. Again, the larches and other pines of Norway or Great Britain 

 are quite equal in size to any coniferse which we find in the coal ; and 

 there are plenty of arborescent ferns in New Zealand in a latitude of 

 nearly 46° south. It is well known that the great extent of ocean 

 gives uniformity and mildness to the climate of the southern hemis- 

 phere, rendering the summers more cool, and the winters warmer, than 

 they are in the same parallel of northern latitude. " Captain King 

 observed large shrubs of Fuchsia and Veronicay which in England are 

 treated as tender plants, thriving and in full flower in Terra del Fuego, 

 (lat. 55° S.) with a temperature of 36°. He states also that humming- 

 birds were seen sipping the sweets of the flowers after two or three 

 days of constant rain, snow, and sleet, during which time the thermo- 

 meter had been at the freezing point Mr. Darwin also saw parrots 

 feeding on the seeds of a tree called 'winter's bark,' south of latitude 

 55°, near Cape Horn." 



* In a more recent work, viz., " Incidents of Travel in Yucatan," by J. L. Stephens, Esq. 

 a sketch is given to show the manner in which the rankness of tropical vegetation is 

 hurrying to destruction these interesting remains of an extinct race. ''*' The tree is called 

 the alamo or elm, the leaves of which, with those of the ramon, form in that country the 

 principal fodder for horses. Springing up beside the front wall, its fibres crept into cracks 

 and crevices, and became shoots and branches, which, as the trunk rose, in struggling to 

 rise with it, unsettled and overturned the wall, and still grew, carrying up large stones 

 fast locked in their embraces, which they now hold aloft in the air. At the same time, 

 its roots have girded the foundation wall, and form the only support of what is left ; and 

 no sketch can convey a true idea of the ruthless gripe in which these gnarled and twisted 

 roots encircle sculptured stones." — Vol. i. p. 394. 



