GYMNOSPERMiE. 



139 



If we examine this table, and contrast the Conifera3 of England in it with those 

 of Scotland and Ireland, we discover indications of considerable differences in 

 temperature. The varieties of Callifris, Cupressus, Taxodium, and Araucaria are such 

 as are to be found growing in company near the water's edge in Madeira, whilst the 

 more northern assemblage would be found there in grounds a couple of thousand feet 

 above the sea. Farther north, in the Greenlandic Eocene, the North-British Cupressus, 

 Podocarpus, and Cri/ptomeria give way in turn to a still more temperate assemblage, 

 comprising the Red-wood, Deciduous Cypress, and probably Juniper, Thuja, Cephalo- 

 taxus, and Fir, while the Yew, Pines, and Ginkgo maintain their ground. There is 

 thus little reason to believe that the climate of the Northern Hemisphere, though very 

 much hotter during a part of the Tertiaries than at present, was then more uniform than 

 now. An extensive migration of species, consequent on a considerable rise and fall of 

 temperature, has caused the same plants in some cases to become embedded in very 

 different latitudes, but it needs no argument to prove that all these widely separated 

 deposits need not necessarily be of exactly the same age, and there is fortunately ample 

 evidence in support of this. Not a single species of Conifer from either Ireland or Scotland, 

 with the exception of Ginkgo, which first appears in southern Europe in the latest 

 Miocene or possibly the Pliocene, has ever been met with in any beds of known 

 Miocene age, and to maintain longer that the great Basaltic formation is in its entirety 

 of the latter age, is simply to ignore the accumulated evidence. 



The close connection of the Eocene Flora of the English basin with the present 

 Australian Flora is another of the most obvious of the facts to be gathered from this table. 

 The two species of Frenela {Callitris) and the Aihrotaxides, known by their fruits, are 

 purely Australian types, while the Araucaria and some of the Podocarps, though less 

 perfectly known, are no less characteristically Australian. All these elements completely 

 disappear from the Scotch and Irish Eocene basin, the plants of which seem mainly 

 related to those of Eastern Asia. The essential difference between the Floras of our 

 northern and southern basins, apart from the respective temperatures required by them, 

 appears to lie in the fact that, whilst the former were almost restricted to types now 

 indigenous to Eastern Asia, the latter possessed, in addition to these, types now peculiar 

 to Australia and America. 



In order to complete the Monograph as far as possible, the following Tables of 

 Reference are appended, showing all the Conifera3 from British rocks of early Tertiary 

 age recorded previous to the commencement of this work, and the position now assigned 

 to them : 



Names as published. 

 Cupressinites globosus, Bow. 

 ,, elongatus, Bow. 

 „ recurvatus. Bow. 

 „ subfusiformis, Bow 



Status in this Monograph. 

 - Believed not to be Coniferous. 



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