144 RECOEDS OF THE AUSTRALIAN MUSEUM. 



space between them being again structureless. This section, which 

 was prepared from a stem fragment enveloped in matrix in the 

 hope that it would display the longitudinal structure simply, has 

 by accident revealed other unexjjected details, in the form of tliree 

 bract-like bodies on each side, opposite to one another, two and 

 two, those on the right being better preserved than those on the 

 left. As sectioned they form an extension of the parenchymatous 

 zone, and are margined by a continuation of the amber-brown 

 exodermic layer, which is cellular, the tissue having the appearance 

 of the epidermal of the fronds. The two lowest bodies are the 

 longest and best preserved. The only suggestion I can ofter of 

 this structure is that the section at this point traverses a node, 

 and that we here see petioles of some of the fronds. 



In the same section, but detached from this caudex fragment, is 

 what may well be termed a root and rootlets (PI. xxiv,, fig. 13). 

 The former is straight, 2'7 mm. long, with a transverse measure- 

 ment of 1*5 mm., and from it on each side are given otf at right 

 angles longer and shorter processes, varying in length from 0*15 to 

 03 mm. There is no structure preserved. Whether or no these 

 are a root and rootlets of the plant under consideration, it is of 

 course impossible to say. 



•Could further points of structure be made out in this interesting 

 fossil, a comparison might then be instituted with that of Lygino- 

 dendron, Will., on the one hand, and that oi Heterangium, Corda, 

 on the other. On a superficial comparison with figures of both,* 

 a general resemblance is noticable, particularly in the central 

 cylinder, and the surrounding zone of secondary wood, but as we 

 are unacquainted witli the constitution of the central cylinder, 

 whether of pith and primary wood, as in Lyghiodendron, or 

 primary wood alone, as in Heterangiuin,-\ it is impossible to carry 

 the comparison further, 



One very interesting point, however, remains to be referred to — 

 the attachment of a fern foliage to stems with affinities of a higher 

 order. The late Prof. W. C. Williamson suggested J that the 

 rachises of certain ferns known as Rachiopteris aspera, from a 

 similarity in some of their tissues to those of Lyginodendron, were 

 the petioles of the leaves of that genus. He remarked — " If we 

 are correct in this supposition, we have now, for the first time, in 

 Lyginodendron Oldhaniiuin, a Fern of which the stem or rachis 

 exhibits a highly developed form of exogenous growth. . . Some 

 months ago Mr. Kidston sent me some stems which he believed 



* Williamson — Phil. Trans, for 1873, clxiii., pi. xxii., fig. 1 ; Williamson 

 and Scott — Ibid. (B) for 1895, clxxxvi., pi. xviii., fig. 1; Seward — Ann. 

 Bot., xi., pi. v., fig. 1. 



+ Williamson and Scott — Loc. cit., clxxxvi., p. 745. 



i Phil. Trans. (B) for 1887, clxxviii., p. 298. 



