of Ulodendron to Lepidodendron, &c. 127 



He defined Ulodendron as follows : — " Stem not furrowed, 

 covered with rhoraboidal marks. Scars of cones circular;" 

 and Botlirodendron — " Stem not furrowed, covered with dots. 

 Scars of cones obliquely oval." Buckland believed that the 

 cones were only attached to the centre of the large scars, and 

 that the furrows on the upper parts of the scars, which radiate 

 from the umbilicus^ were formed by the scales at the base of 

 the cone pressing against the bark. 



1837. Brongniart. Histoire des v^g^taux fossiles, vol. ii. 

 p. 69. — Brongniart, as in his ' Prodrome,' here places 

 Ulodendron among the Lepidodendra. On pi. xviii. he gives 

 a figure of Lejpidodendron Veltheirnianum under the name of 

 Lepidodendron ornatissirnum ; on pi. xix. four other figures 

 of Ulodendra are given under the name of Lepidodendron ; 

 one of these (fig. 1), at least, if not all, belongs to Sigillaria 

 discophora^ Konig, sp.= (Z7. majus, L. & H.). Brongniart 

 points out the peculiar character of the bark becoming fissured 

 in those examples which bore the Ulodendroid scars, which is 

 a character not common to most Lepidodendra. The presence 

 of these furrows he thought indicated that the specimen pos- 

 sessing them belonged to the lower part of the stem, and that 

 they were caused by adventitious roots bursting through the 

 bark. 



He argues that had the large scars been originally 

 covered with the ordinary cauline leaves, they should follow 

 the ordinary spiral series of the stem, which he says they do 

 not, each disk showing in the cicatrices which cover it a series 

 of spirals peculiar to itself*. Or if they were the impressions 

 of the scales of the cone, which had completely efi'aced 

 from the surface of the stem all traces of the organs that it 

 bore, then the impressions of the appendicular organ on the 

 stem should have been in an inverse order from the leaf- 

 scales of the stem, because the extremities of the scales of the 

 cone are convex and should have made depressions on the 

 stem. On the contrary, the marks presented on the Uloden- 

 droid scars are similar to those of the leaves on the stem. 



1848. Hooker. " On the Vegetation of the Carboniferous 

 Period as compared with that of the present Day," Memoirs 

 of the Geological Survey of Great Britain, vol. ii. part ii. 

 p. 427. — Of Ulodendron^ Sir Joseph Hooker says : — " This 

 very remarkable genus scarcely difi'ers from Lepidodendron 

 in internal structure : its external aspect widely differs from 

 that of any plant, recent or fossil, with which I am ac- 

 quainted. I have seen in collections specimens which have 

 been fossilized, apparently erect, or, at any rate, under very 

 * See description of specimens Nos. 3 and 7. 



10* 



