HALONIA. 



85 



similarity exists in the cliaracter of tlie striated tubes whicli surround the medullary 

 column, and the pseudo-vascular bundles of certain Zamia. Neither are these plants to 

 be referred to that class which includes the Sigillaria, Anahathra, &c. ; for, although the 

 structure in some important respects may correspond, the arrangement of the tubes of the 

 vascular system is altogether reversed ; consequently, the curved scalariform bundles, 

 whicli traverse the stem from its axis to the periphery, do not emerge from the tissues imme- 

 diately in connection with the medullary column, but are thrown off from the outer 

 portion of the sheath. These leaf-cords, which appear somewhat to resemble the stem in 

 miniature, take a direction for some distance nearly horizontal, so that different portions 

 of the tissues of several neighbouring bundles are usually cut through, giving to the 

 transverse section some appearance of a radiated structure. I should observe, that these 

 fascicuU differ in size, the smaller ones having a direction towards the spirally arranged 

 scars which cover the surface of the stem ; the larger ones being connected with the pro- 

 cesses that occur upon it at certain intervals, each of these projections exhibiting a 

 roundish cicatrix at its apex, as though some leaf-like appendage had been supported upon 

 it, and having some resemblance to the well-known tubercles of 8iigmaria. These few 

 observations will be sufficient to show that the fossil in question belonged to the vascular 

 Cryptogamia ; and that, when compared with the other plants of tlie Coal-measures, the 

 nearest affinity is with Lepidodendron. We might, in fact, considering their tortuous 

 root-like appearance, and on other accounts, be tempted to speculate as to the relationship 

 they bear to this fossil ; but possibly some other specimens in my possession, not yet suffi- 

 ciently examined, may throw further light upon the subject. 



" Since the above remarks were forwarded to the Society, I have been fortunate 

 enough to obtain some very good sections of another specimen of this fossil, and am now 

 enabled to mention a peculiarity in the structure which had previously escaped notice, viz., 

 that a narrow ring of very regular, compact, elongated tissue exists on the outer portion 

 of the cortical zone (e), similar to the prosenchymatous arrangement mentioned as occurring 

 in the corresponding part of the Lepidodendron. Having, however, had an opportunity 

 to look through many specimens of this latter fossil, I may venture to say that the descrip- 

 tions hitherto given of it do not in this and some other respects correctly represent its 

 structure. Such discrepancies have probably arisen from the inferior state of the specimen 

 first met with by the Rev. C. G. Vernon Harcourt, and also in consequence of Mr. Witham 

 having originally figured from portions of two distinct fossils, apparently mistaking in one 

 instance an imperfect fragment of Halonia for a piece of Lepidodendron (see ' Transactions 

 of the Natural History Society of Newcastle,' 1832, and 'Internal Structure of Fossil 

 Vegetables,' Edinburgh, 1833, pi. xii, fig. 3 ; pi. xih, fig. 1). Brongniart indeed admits 

 being unable to detect this exterior tissue ; but nevertheless describes it both in his 

 ' Histoire des Vegetaux Fossiles ' and in the ' Archives du Museum d'Histoire Naturelle ' 

 upon English authority ; he has, however, discovered a very similar tissue, although dif- 

 ferently placed, in the cortical zone of the Sigillaria elegans. 



