CLIMATE OF ^PLEISTOCENE PERIOD. 53 



The tufas of Canstadt, near Stuttgardt, have yielded the 

 following species, which are common to the similar deposits of 

 Southern Europe : — 



Scolopendrium officinale (hart's-tongue). 



Quercus pedunculate/, (oak). 



Fagus sylvatica (beech). 



Gorylus avellana (common hazel). 



Ulmus campestris (elm). 



Populus alba (white poplar). 



Salix cinerea (gray willow). 



Cornus sanguinea (common dogwood). 



Acer pseudo-platanus (sycamore). 



Buxus sempervirens (box). 



Euonymus europceus (spindle-tree). 



Tilia grandifolia (lime). 



The total number of species is twenty-nine, of which three 

 are extinct, namely the mammoth oak (Quercus mammouthii), a 

 poplar {Populus Fraasii), and a walnut tree, which, according to 

 Heer, resembles the American black walnut (Juglans nigra) and 

 butter-nut (J. cinerea) in the toothed pinnae of its leaves. With 

 the exception of these extinct forms and the box, all the species 

 met with in the tufa still occur in Wurtemberg. The sycamore, 

 however, and the whortleberry, which is also common to the tufa, 

 are not found now in the neighbourhood of Canstadt, the former 

 growing on the mountains and the latter in peat-bogs. Heer thinks 

 that the climatic conditions implied by the flora of the tufa are 

 s imil ar to those now prevalent in the same locality, but Saporta 

 points out that the difference between the Canstadt flora and that 

 of Southern Europe in the Pleistocene Period was really much 

 less than it is at present. Several species which nowadays are 

 found in the Mediterranean region only in the mountains, such 

 as the beech, the lime, the maple, the sycamore, etc., descended 

 in Pleistocene times to the low grounds of Middle Italy. The 

 vegetation of Wurtemberg was distinguished from that of 

 Southern Europe chiefly by the presence of firs, and by the 

 absence of the more southern forms, such as vine, fig, judas- 

 tree, laurustinus, etc. But, as we have seen, out of a total 



