IQQ FOSSIL PLANTS. 



Lepidodendron Veltheimianum, must be removed from Lepidodendron and 

 placed in a separate genus, but not in Ulodendron, as at present constituted, 

 and for the following reasons : Those who still regard Ulodendron as a true 

 genus include in it two distinct groups of plants those with leaf-scars 

 identical with Lepidodendron, as Ulodendron parmatum, and others with 

 leaf-scars identical in form and arrangement with the Clathrarian-Sigillaria 

 as in Ulodendron majus, L. and H. (= Ulodendron minus, L. and H.). Now 

 in Lepidodendron and Sigillaria the form and arrangement of the leaf -scar is 

 the character in which generic difference chiefly lies, but in Ulodendron, 

 where plants closely allied to the two former genera are included, the 

 character of the leaf -scar is all but entirely ignored. 



It is true that Ulodendroid specimens seldom show the leaf-scars well 

 preserved, and that on many of the described species of Ulodendron they 

 have not been observed ; still that does not alter the fact that when well- 

 preserved examples are examined, the leaf-scars conform to the two types, 

 as already indicated. If then the form of the leaf -scar is of generic value in 

 Lepidodendron and Sigillaria and I think most Botanists will agree in the 

 importance of this character on what grounds can we ignore the value of the 

 same character in Ulodendron ? Therefore, if those species with Ulodendroid- 

 scars are to be excluded from Lepidodendron and Sigillaria, it will be 

 necessary to form two genera for these plants one for Lepidodendroid- 

 Ulodendra, and the other for Sigillarian-Ulodendra. This view, however, I 

 am not prepared to adopt, as I think the plants find a suitable and natural 

 place in Lepidodendron and Sigillaria respectively. 



This subject I intend to enter into more fully at a future time, when I 

 hope to figure some specimens on which the above views have been founded. 



Under Lepidodendron Veltheimianum, Stur, in his Culm Flora, has in error 

 included on pi. xxxix. figs, la, b, and 2, two figures of Sigillaria Taylori, Carru- 

 thers, sp. Both of these figures are exquisite examples of old stems of the 

 plant described as Ulodendron Taylori by Mr. Carruthers (Monthly Micros. 

 Journal, p. 152, pi. xliii. fig. 1, March 1870). Mr. Carruthers' specimen does 

 not, unfortunately, show clearly the form of the leaf -scar. 



Lepidodendron acuminatum is only a varietal form of Lepidodendron Velthei- 

 mianum, with which it has already been united by Schimper. Lepidoden- 

 dron geniculatum is also merely a form of the same species. Lepidodendron 

 patens (Selaginites patens), Brongniart, from the neighbourhood of Edin- 

 burgh, is likewise to be referred to Lepidodendron Veltheimianum. The 

 peculiar appearance of this fossil is caused by the basal portions of the leaves 

 still retaining their attachment to the stem, and in other cases I have observed 

 a very similar appearance produced by the leaves being addressed (probably 

 through mechanical agency) to the branches. 



Although not in doubt for a moment that those specimens to which I refer 

 are similar to that figured in vol. ii. pi. xxvi. of the Hist. d. V6g6t. Foss., 

 examples with such an extremely scaly appearance are rare ; but I have one 

 at least where it is as well marked as on the type figure of Lepidodendron 

 patens, Brongt., sp. 



Schmalhausen has united Lepidodendron Glincanum, Eichwald, and Lepido- 

 dendron Volkmannianum, Sternberg, with Lepidodendron Veltheimianum, 

 Sternberg.* In regard to Lepidodendron Glincanum, I cannot find any point 

 by which it can be distinguished from Lepidodendron Veltheimianum, and 

 therefore include it under that name ; but Lepidodendron Volkmannianum 

 seems an altogether distinct species, and cannot be united with Lepidodendron 

 Veltheimianum. 



Lepidodendron (Sagenaria) Glincanum, Eichwald (Lethsea Eossica, pi. va, 

 fig. 7), should perhaps be referred to Lepidodendron Volkmannianum. 



Lepidodendron (Sagenaria) aculeatum, Feistmantel and Goppert (I.e.), Lepi- 

 dodendron selaginoides, Lepidodendron Sternbergii, Heer (I.e.), and Sagenaria 



* Mem. 1'Acad. d, Sc. de Potersbourg, rii" ser. vol. xxxi. No. 13, p. 11. 



