80 CONIFERAE. 



place the particular notices of them to be found in the literature. But 

 I should wish briefly to mention one fossil at present in danger of being 

 forgotten, the connection of which with the Coniferae seems to have been 

 well established by means of sections prepared from a silicified fragment. 

 I allude to Tylodendron speciosum, Weiss *, found originally in the sand- 

 stone of the lowest beds of the Rothliegende at Ottweiler near Saarbrucken, 

 together with much silicified wood, and afterwards detected by Zeiller 2 in 

 the Permian beds of la Correze near Brive. Weiss associates with it various 

 similar casts of branches described and figured by Eichwald 3 which come 

 partly from the Carboniferous limestone, partly from the Permian deposits 

 of Eastern Russia. His own figures of Tylodendron speciosum show straight 

 branches without ramifications as much as seventy centimetres in length, 

 resembling the topmost shoots of Conifers, and everywhere covered with 

 narrow rhombic convex spirally arranged leaf-cushions, each of which shows a 

 groove-like impression in its upper portion. The branches swell at regular 

 intervals and become fusiform, and the lower half of the swollen part is 

 marked by the great abbreviation of the cushions on its surface, exactly in 

 the manner usually to be observed in our pines at the extremity of the 

 annual shoot where it is covered with bud-scales. Our knowledge of the 

 anatomy of the plant is imperfect, but Weiss gives a radial section which 

 shows exactly the picture of one of the coniferous woods which are classed 

 with Araucaroxylon, and thus we have proof that the fossil belongs to the 

 group under consideration. 



It is well known that fragments of wood having the structure of living 

 Conifers are found in every state of preservation throughout the entire series 

 of geological formations from the middle Devonian upwards, and that they 

 begin to be common everywhere as early as the higher members of the 

 Coal-measures. Great hopes therefore have long been entertained that 

 their examination would supply important results and points of departure. 

 To Goppert 4 must be assigned the first place in the cultivation of this field 

 of research. Owing however to the uniformity of structure which charac- 

 terises secondary growth in thickness in Coniferae, these efforts have not 

 been crowned with that measure of success which might have been expected. 

 First of all it has become apparent that other groups, very near the Coni- 

 ferae it is true but still distinct from them, as for example the Palaeozoic 

 Cordaiteae, possess a woody structure so like that of Coniferae, that it is 

 impossible to distinguish them unless we have entire sections of a stem 

 before us. Further, Goppert has perceived that it is only in the rarest 

 cases that we can distinguish the genera within the class by the structure 

 of the wood, and that oftentimes even the members of different families. 



Weiss (1), p. 185. a Zeiller (4), t. 8, f. i. 3 Eichwald (1). 4 Goppert (6) and (4). 



