84 CONIFERAE. 



belong to Cordaitae. It has been already stated that the Cordaitae show 

 the structure of Araucaroxylon, and that they include a large portion of 

 the palaeozoic woods. But that there were also true Conifers with the 

 same woody structure in the Carboniferous and Permian eras is proved 

 from the descriptions given of Tylodendron speciosum, Weiss 1 . The 

 hitherto doubtful Aporoxylon primigenium, Ung. 2 , from the Cypridina- 

 schists (Upper Devonian) of Saalfeld has recently been unmasked by 

 Goppert 3 through the discovery of radial pits most of which had disap- 

 peared, and has been determined to be an Araucaroxylon. 



Under the names of Prototaxites Logani and Nematoxylon eras- 

 sum Dawson 4 has described silicified wood from the Lower Devonian 

 beds of Canada and New Brunswick, entire stems of which were observed 

 in the cliffs of Little Cape Oiseau near Gaspe", as the oldest known coni- 

 ferous remains. Pieces in which the structure is preserved show circular 

 transverse sections of cells not arranged in any order, and separated from 

 one another by homogeneous partition-walls of unusual thickness. The 

 longitudinal section shows that their substance is composed of very long 

 uniform tubes which appear to bend irregularly hither and thither and to 

 intertwine, and not to run in regular and parallel lines as in normal wood of 

 Conifers. The spiral striation, on account of which Dawson chose the 

 name Prototaxites, has however nothing in common with Taxus ; the thick 

 wall is seen in the longitudinal section to be traversed by striae, narrow 

 tubes, confusedly interwoven. His bordered pits look more like cross views 

 of these striae. Carruthers 5 , to whom we are indebted for an exact account 

 of the matter, finds no resemblance to the structure of coniferous woods, 

 and thinks that Prototaxites must be considered to be an alga-stem. I 

 have satisfied myself by examining preparations of material supplied by 

 Dawson himself that the fossil has little in common with Coniferae ; it may 

 possibly be an Alga, but I can find no direct analogue for it among the 

 forms known to me, and Halimeda and similar plants suggested by Car- 

 ruthers can scarcely be brought into the comparison. Stems of Fucaceae 

 with growth in thickness as represented by Reinke might at first perhaps be 

 thought of, but these differ in not unessential points from the descriptions 

 of Prototaxites. The same form, or one absolutely similar, has very recently 

 been found in Wales in the much older Silurian beds of the Upper Land- 

 overy formation in the shape of small silicified partly brown, partly coal- 

 black fragments cemented into the rock, and showing the described structure 

 most beautifully. These plant-remains, which are named Nematophycus 

 Hicksii, Eth. 6 , are without doubt the very oldest in which the structure still 

 preserved can be clearly seen. 



1 Weiss (1). - Unger (5\ 3 Goppert (6). 4 Dawson (1), p. 16, t. 12. ' Carruthers <5). 

 c Hicks (1), and Dawson (1), vol. ii, p. 107, and 3. 



