1851.] BUNBURY ON A FOSSIL FERN. 33 



although in general widely different in their outward appearance, are 

 very closely allied in all essential points of structure, so that all bo- 

 tanists have agreed in placing them next to one another, and some of 

 the most eminent have even united them under one head. Sir W. 

 Hooker, for instance, in two or three of his admirable works on Ferns, 

 has actually comprehended the Club-mosses as a subordinate group. 

 Hence it would not be utterly inconceivable, that, in a former state of 

 the world, there should have existed plants combining some of the 

 peculiarities of the two orders, and uniting them more closely than is 

 done by any existing form. I am inclined to think, however, that 

 this hypothesis is not applicable to the specimen now before us. 



On a close examination of the stem, we shall fail, I think, to dis- 

 cover the proper characters of a Lepidodendron. There is no 

 appearance of that regular dichotomous division which has been 

 justly insisted On by M. Brongniart as an important characteristic of 

 Lepidodendron ; on the contrary, the only stem in this specimen 

 which is branched, has branches irregularly alternate, and very in- 

 ferior in size to the main axis. Again, the stems here have a wavy 

 and winding character, an appearance of softness and flexibility, which 

 I have not seen in any genuine Lepidodendron. In L. elegans and 

 L. gracile, the most branched kinds with which I am acquainted, 

 even the youngest and slenderest branches are almost always straight, 

 and have a certain rigidity of character which is wanting here. 

 Again, although the younger parts of the stem, in the specimen before 

 us, exhibit superficial markings a good deal like those of the young 

 branches of a Lepidodendron, yet the areoles are irregular and ill- 

 defined, and without distinct leaf-scars. On the main stem all 

 appearance of regular and definite areoles has vanished, and the 

 surface is merely indented or pitted, in a manner very similar to what 

 we observe in undoubted fossil Fern-stalks {stipites). On the other 

 hand, it is well known how definite and regular are the areolar mark- 

 ings of true Lepidodendra, even on stems of great size and age*. 



For these reasons, I can hardly believe that any part of the spe- 

 cimen in question belongs to the genus Lepidodendron. I may 

 mention, too, that when I showed it to the greatest of modern bo- 

 tanists, he pronounced the plant to be truly a Fern, and nothing 

 else. 



The conjecture I have to offer — for I can call it no more than a 

 conjecture — is that this curious fossil may possibly be a Fern with a 

 creeping stem or rhizome, such as are so commonly seen in moist 

 tropical climates, creeping like ivy over mossy rocks and old trunks 

 of trees. Polypodium incanum, P. percussum, P. vaccini/olium, and 

 P. lycopodioides are well-known examples of this mode of growth, 

 and are often to be seen in botanical collections. The creeping stem 

 of such Ferns has often a striking resemblance at first sight to a 

 Lycopodium, as indeed is indicated by the name of one of the plants 

 above-mentioned. At the same time it is by no means regidarly 

 dichotomous, but has an irregular ramification, often very similar to 



* L. selaginoides (of the " Foss. Flora") is an apparent exception, but I strongly 

 suspect that it is not a true Lepidodendron. 



VOL. VIII. PART I. D 



