100 PAL^ONTOLOGICAL BOTANY. 



continent or of the United States. A few only are of genera 

 existing in India, Japan, and the north of Africa. These 

 various floras, which present successively the character of 

 those of inter-tropical, sub-tropical, and temperate regions, 

 seem to indicate that central Europe has, since the com- 

 mencement of the Tertiary period, been subjected, during the 

 succession of time, to the influence of these three different 

 temperatures. It would appear, then, Raulin remarks, that 

 the climate of Europe has during the Tertiary period gra- 

 dually become more temperate. 



Brown coal occurs in the upper Tertiary beds, and in it 

 vegetable structure is easily seen under the microscope. 

 Goeppert, on examining the brown coal deposits of northern 

 Germany and the Rhine, finds that Coniferge predominate in 

 a remarkable degree; among 300 specimens of bituminous 

 wood collected in the Silesian brown coal deposits alone, only 

 a very few other kinds of Exogenous wood occur. This seems 

 remarkable, inasmuch as in the clays of the brown coal for- 

 mation in many other places leaves of deciduous Dicotyle- 

 donous trees have been found ; and yet the stems on which 

 we may suppose them to have grown are wanting. The leaves 

 have been floated away from the place where they grew by a 

 current of water which was not powerful enough to transport 

 the stems. The coniferous plants of these brown coal deposits 

 belong to Taxine^e and CupressineaB chiefly ; among the plants 

 are Pinites protolarix and Taxites Ayckii. Many of the Coni- 

 ferse exhibit highly compressed, very narrow annual rings, such 

 as occur in Coniferee of northern latitudes. Goeppert has 

 described a trunk, or rather the lower end of a trunk, of 

 Pinites protolarix, discovered in 1849 in the brown coal of 

 Laasan in Silesia. It was found in a nearly perpendicular 

 position, and measured more than 32 feet in circumference. 

 Sixteen vast roots ran out almost at right angles from the 

 base of the trunk, of which about four feet stood up perfect 



