GEOLOGY OF PART OF SOUTH DURHAM. 175 



numerous, in the Brockwell at the George Pit, Etherley, and 

 Newfield Colliery. At Lands the matted fronds of Alethopteris 

 loncliitidis and Serlii, and Pecopteris dentata filled the shale of 

 the roof in some parts of the pit, while those of Neuropteris he- 

 terophylla and Pecopteris laciniata were as common in others. 



We shall allude to the distribution of these fossils further on. 



In an important work on the Coal Formation of Saxony, Dr. 

 Hanns Bruno Geinitz, of Dresden, has some interesting obser- 

 vations on the distribution of the vegetable fossils found therein. 

 He states that different groups of coals are characterised by 

 peculiar groups of fossil plants, and of these palseontological 

 features he makes use in his classification of the formation. To 

 quote from a resume of the work, in the anniversary address of 

 the President of the Geological Society for 1857, we have these 

 remarks : — 



"The great divisions of the Saxon coal-field may be stated as 

 follows. 



" 1. The coal formation of Hainech-Ebersdorf, which is the 

 earliest band of vegetation in Saxony. 2. The Sigillaria-coal, 

 in which the remains of such plants predominate over all others ; 

 this coal is the lowest bed in the Zwickau basin. 3. The Cala- 

 mite-coal, in which a forest of Calamites, including some of the 

 largest known species, appears to have been buried, mixed, of 

 course, with species of other genera. 4. The next zone is also 

 rich in Calamites, though not in the same proportion as in the 

 one below, the Calamites approximate being however the most 

 abundant. The Annularia longifolia finds its peculiar horizon 

 here in which it attains its highest development, though found 

 in beds both above and below. 5. The last girdle or zone of 

 vegetation is characterised by an abundance of ferns, since, of 

 ninety-eight species of plants, fifty belong to this family of 

 plants." 



"The fifth zone has eighteen species in common with the 

 fourth, the same number with the third, and even somewhat 

 more with the second; but as Geinitz observes, it is not so 

 much the relative number of species, here so striking, which 

 gives a peculiar character to the flora, as the number of 



