b GEOLOGICAL MEMOIRS. 



coal deposits alone, only a very few {nu?' ein paar) other kinds of 

 dicotyledonous wood occur. This seems the more remarkable, since 

 in many places leaves of dicotyledonous trees with deciduous foliage 

 have been found in the clays of the brown-coal formation, and yet in 

 the coal-beds the trees on which we may suppose them to have grown 

 are wanting. This might be regarded as indicating a formation from 

 drift-wood, but the following considerations are opposed to this view. 

 In the brown-coal beds at Blumenthal near Neisse, wood of deci- 

 duous trees occurs along with twigs and fruits of a Taxus and Cu- 

 pressinea ; amongst the trees only Taxus and Cupressinea, with no 

 trace of any other kind of dicotyledonous tree. This seems an im- 

 portant fact, as perhaps leading to an explanation of this remarkable 

 phsenomenon. I believe that during the process of maceration and 

 decomposition, to which the vegetation of the brown-coal forests was 

 subjected before it was buried between layers of earth and protected 

 from atmospheric influences, the deciduous-leaved trees lost their 

 organic connection sooner than the highly resinous wood of the coni- 

 ferae, and hence fell to pieces, whilst the latter were for the most part 

 preserved, — a view, so far as I know, in harmony with the result of 

 experience on the duration of these kinds of wood in similar circum- 

 stances. I throw out this however only as a conjecture, which may 

 perhaps be subsequently confirmed by an examination of different 

 brown-coal deposits. 



2. The number of species is on the whole very small in comparison 

 with the enormous mass of brown-coal they have contributed to form, 

 from which we may conclude that the conifer se of the ancient world 

 had a similar gregarious mode of growth with those that now flourish 

 on the earth. To prove this in certain beds, even for single species, 

 I collect as many specimens of different trunks or fragments of bitu- 

 minous wood as are to be found, and then examine them. From this 

 the predominance of certain species at once appears, and though 

 it may be justly remarked that several fragments of one and the same 

 tree may often occur, still frequent repetition of this somewhat labo- 

 rious process at last enables us to obtain a result approaching nearly 

 to certainty. 



3. The fossil species are remarkably distinct from those of the pre- 

 sent coniferous flora of northern Germany ; few resemble our Pinus 

 Abies and Picea, and I have hitherto only found a single species with 

 the structure of Pinus sylvesti'is, or generally of the genus Finns as 

 limited by Richard and Link ; the greater part agree with Cupres- 

 sinea, if we may judge from the smooth bark of the larger stems, the 

 sharply-defined annual rings, the small number of cells contained in 

 a medullary ray, although there are exceptions to this rule ; whilst the 

 predominance even quantitatively of the form of Taxus, of which I can 

 well distinguish at least four species, is remarkable. Among them 

 are species of which the wood, formed of cells with thick walls, is 

 denser and more compact than that of the existing Taxus ; but also 

 one species of uncommon lightness and with large cells, similar to the 

 wood of the North American Taxus montana, Nutt., or Torreya taxi- 

 folia, Arnott. My present as well as former researches show as a 



