204 



LEPIDODENDREAE, 



an essentially different appearance in the remains which Ettingshausen l 

 connects with this species, and are almost equal in length to those of L. 

 longifolium, Brongn., with which Schimper places them. Fine branches 

 with broadly lanceolate leaves are described in the same publication of 

 Ettingshausen as L. Haidingeri 2 , and others with short linear leaves as L. 

 brevifolium, Ett. :! Lastly, the name L. selaginoides, Stbg is given by 

 authors to certain portions of branches with many ramifications, which are 

 furnished with short leaves incurved and hooked after the manner of Arau- 

 cariae or Walchiae. I have found such leaves in great abundance near 

 Saarbrucken, and particularly fine specimens of them occur in the clay- 

 ironstone nodules of Coalbrook Dale in England ; figures of them will be 

 found in Brongniart 4 , O. Feistmantel 5 , Lindley and Hutton 6 , and Schmal- 

 hausen 7 . The forms known as Lepidophyllum and regarded by Stur as 

 foliage-leaves of Lepidodendron will be noticed again in a subsequent page. 

 But it is not only in the form of the leaves that the foliage-branches 

 which have been described differ from one another ; the leaf-bearing axes 

 themselves vary much in character. Some are stiff, little or not at all 

 branched, and of remarkable thickness, as for example in Ettinghausen's 

 Lepidodendron brevifolium, L. Sternbergii, and L. Haidingeri; others are 

 thin and slender like so many rods, and are then usually copiously branched 

 with repeated bifurcations, as is the case in general with the forms named 

 Lepidodendron selaginoides. It cannot be doubted that these differences 

 indicate important variations in the construction of the entire head of the 

 trees, which in the latter case may have been copiously and densely 

 branched with the terminal ramifications occasionally pendulous, while in 

 the other case its branches may have been stiff, open, and few in number. 

 And this leads to the consideration of the morphological building up of the 

 entire plants, of which we have hitherto been discussing the separate parts. 

 In numberless cases, as has been observed more than once before, both in 

 evident Lepidodendrae and in Knorriae also, we can point to clearly ascer- 

 tained dichotomies, which repeat themselves sometimes in larger fragments 

 in the successive branch-generations. For this we may appeal to the 

 figures already cited. As frequently, and usually on the same pieces with 

 the dichotomies, we find lateral branching also variously distributed. Cases 

 of this kind may in wonted measure and following the opinion of authors 

 be explained by assuming sympodial development of the dichotomous 

 systems, though it seems scarcely necessary to have recourse to this method, 

 now that we know that the two forms of branching are present side by side 

 in Psilotum, that in fact there is no fundamental difference between them. 



1 von Ettingshausen (5), tt. 26-28. 2 von Ettingshausen (5), t. 22. 3 von Ettingshausen (5), 

 t. 25. * Brongniart (1), vol. ii, t. 17. 8 O. Feistmantel (3), tt. 30, 31. 6 Lindley 



and Hutton (1), vol. i, t. 12. 7 Schmalhausen (2), t. 2, ff. 5, 6. 



