94 



PAL^ONTOLOGICAL BOTANY. 



by the Duke of Argyll.* Above and below these beds basalt 

 occurs, and there are peculiar tufF-beds alternating with the 



Fig. 98. 



leafy deposits. These tufF-beds were formed by the deposit 

 of volcanic dust in pools probably of fresh water. They 

 contain fragments of chalk and flint. The leaves are 

 those of plants allied to the Yew, Rhamnus, Plane, and 

 Alder, along with the fronds of a peculiar Fern, and the 

 stems of an Equisetum. The genera are Taxites or Taxo- 

 dites (Fig. 100), Rhamnites (Fig. 101), Platanites, Alnites, 



and toothed, found in Bohemia. Fig. 98. Rhamnus Aizoon, a petiolate 

 elliptical obtuse feather-veined leaf, with an entire margin, found in 

 Styria. 



* Journ. Geol. Soc. of London, vii. 



