176 Mr. R. Kidston on the Relationship 



which so frequently occur on large Ulodendroid stems. The 

 leaf-scars on this fossil are, however, larger than they usually 

 are on most Ulodendroid specimens, such as those figured 

 by Brongniart*, Allan f, Stur J, and Schimper§. When the 

 leaf-scars are small they are usually more or less distant (spe- 

 cimen No. .S, PI. IV. fig. 2) ; but with their increase in size, 

 the intervening space becomes gradually reduced till the leaf- 

 scars are contiguous (fig. 1, PI. III.) or nearly so, as in 

 Stur's pi. xxii. fig. 3 h. 



The leaf- scars appear to have been somewhat elevated ; 

 hence, when impressions of the plant are examined, the spaces 

 intervening between the leaf-scars naturally appear as ridges 

 running between them. These ridges, when partially flat- 

 tened over the edges of the leaf-scars by pressure, thus some- 

 what obscure their upper and lower extremities as well as 

 the margins of the leaf-scars generally, and cause the vascular 

 impression to appear as if situated at the extreme upper angle 

 of the leaf-scar ||. It is this state of the plant that has given 

 rise to the supposed " Lepidophloios-condaiion " of Lepidoden- 

 dron Veltheimianum^. 



The Ulodendroid scars, in their earlier condition, are also 

 covered with leaf-scars belonging to the ordinary spiral series 

 of the stem (see specimens Nos. 3 and 7). 



In some cases the bark is quite free from longitudinal fis- 

 sures, as mentioned in the description of specimen No. 2, 

 where from lateral pressure exerted on the leaf-scars by the 

 increase in girth of the stem, they are almost rhomboidal. 

 In PL IV. fig. 2 is shown a small portion of the outer 

 surface of a Ulodendroid specimen. The leaf- scars are dis- 

 tant, and connected with each other by a narrow flexuous 

 ridge. This is more fully described in the notes on specimen 

 No. 3, from which the figure is taken. In fig. 3, PL IV. 

 (specimen No. 4) this character is more marked. In fig. 4, 

 PL IV. is shown a very common form of leaf-scar, occur- 

 ring both on specimens showing the large Ulodendroid scars 

 and also on those on which they are not present, as was 



* Hist. d. veget. foss. voL ii. pi. xviii. 



t Trans. Roy. Soc. Edin. vol. ix. pi. xiv. 



\ Oulm-Flora, pi. xxii. (xxxix.) fig. 3. 



§ Traite d. paleont. v%et. pi. ixiii. 



II Probably, in attempting to reconcile a LepidnpJiloios condition of 

 Lepidodendron with Lepidophloios, Renault has been entrapped into pro- 

 ducing a copy of Goldenberg's figure 6, pi. xvi., on his pi ix. fig. 1, with 

 the vascular scar at the upper end of the cushion, whereas it should have 

 been at its lower extremity. 



^ See Renault, Cours d. botan. foss. deuxieme annee, p. 10, pi. v. 

 fiff. 1. 



