154 THE RECENT. 



mena. Assuming, then, that the life-forms of the Chalk 

 pass insensibly into those of the Tertiary, even though in 

 many European areas the cretaceous era was suddenly 

 brought to a close by the violent displacement of the then 

 land and sea, we yet discover a wide difference between 

 the vital aspects of these respective epochs. In the northern 

 hemisphere the tertiary seas still trend in an easterly and 

 westerly direction stretching diagonally through what is 

 now Central Europe and Southern Asia, spreading over a 

 large tract of Northern Africa, and covering in North Ame- 

 rica wide belts of the Southern States. Shut up from the 

 northern currents that seem to have influenced the chalk 

 seas, and exposed to those which, like the Gulf Stream, 

 partake of a tropical temperature, the climate of the tertiary 

 areas becomes more genial, and is, in the progress of crea- 

 tion, accompanied by a more exuberant flora and fauna. 

 The seas, even in the latitudes of England, teem with 

 southern forms ; while the lands, clothed with a vegetation 

 that finds its nearest analogues in the plants of sub-tropical 

 regions, were tenanted by gigantic mammals which, like 

 the elephant, rhinoceros, hippopotamus, tapir, lion, and 

 tiger, now find their headquarters in the forests and plains 

 of the torrid zone. Extensive lacustrine areas also appear 

 in certain regions, as in Central France, and in their fresh- 

 water forms present, for the first time, a fauna but doubt- 

 fully and obscurely represented in former epochs.* In fine, 



* With the exception of the estuarine beds of the Weald, and the 

 doubtfully estuarine portions of the Carboniferous system, we are al- 

 together ignorant of the fresh-water areas of the older epochs. Lake, 

 river, and marsh must have existed then as now, each peopled by its 

 own distinctive tenantry ; but of these forms we have not a single trace, 

 and it is only as we approach the Tertiary epoch that a fresh-water 

 fauna becomes known and appreciable. As we cannot believe in the 

 total obliteration of ancient fresh-water deposits, so we hopefully look 

 forward to important discoveries in this rich and varied section of 

 vitality. 



