214 FOREST LANDS OF NORTHERN RUSSIA. 



and iii Fraiice. There are the ferns with a foliage often 

 meagre and leathery, equisetacese of the genera equisetum 

 and phyllotheca, cycads, conifers, and lastly some rare 

 monocotyledons. There are there also the forms which 

 are the most generally diffused in England and France, in 

 the Bathonian, the Oxfordian, and the Coralline, and 

 which is seen at Scarborough in Yorkshire, at Mamers in 

 France, and at St. Michael, near Verdun. The resem- 

 blance to those found at Scarborough and with those 

 found at St, Michael is very striking. 



' The flora of Cape Bohenaan contains thirty-two species; 



a third, about ten of them, have been found, moreover, 



and always in the inferior oolite, or the brown jura of the 



Gerrnaus. Amongst the ferns, the Scleropterts pomelii 



Sap., a species of St. Michael, is especially characteristic, as 



it denotes the presence ot a genus which is essentially 



oolitic. The genus Phyllotheca, a type of equisetaceje 



which has been for a long time extinct, has been found, 



first in Australia, and thereafter, by Professor Zigno, in 



the Oxford strata of the Venetian Alps. It was then 



there, a genus of which the extension was immense. And 



the Polar species Phylloiheca later alls, described by Phillips 



and Lindley under the name of Equisitum laterale, has 



just been found in Siberia. We have here, then, a most 



curious type, the sheaths of which, split in segments, 



distinguishes it from the true Equisitum, and approximates 



to the schizoneuva of the Trias, which is found towards 



the centre of the jura spread over the whole land, though 



everywhere pretty rare. 



' This was doubtless a type in a state of rapid decadence, 

 but one which, from that circumstance, seems well fitted 

 to throw light on the equality of temperature which was 

 still general at that moment from one end of the globe to 

 the other. The cycads alone number eight species out of 

 the thirty-two, more than a fourth part of the whole ; and 

 in regard to frequency of occurrence they hold the first 

 rank. The genus Podozamites predominated amongst 

 them : this genus distantly recalls the Zamia of the 



