60 TRANSACTIONS, NATURAL HISTORY SOCIETY OF GLASGOW. 



In the Dalmeny specimen the leaf vascular bundle has a most 

 pronounced development of secondary xylem. This plant is very 

 probablj^ the true Lcpidophloios Harcoiortii, Witham sp. 



It is unsafe to generalize on the differences in the structure of 

 the vascular systems of Lepidodendron and Lepidophloios here 

 pointed out, as our knowledge of them is still very imperfect, but 

 evidence is tending to show that though they both possess the 

 same type of stem structure, there are differences which may 

 enable one to separate the two genera by their internal structure 

 alone. In the case of Lepidophloios fuliginosus and Lepiidophloios 

 Wunschianus, their possessing Halonial branches is conclusive 

 evidence of their belonging to Lepidophloios. It is interesting to 

 note here that though the specimen of Lepidophloios Acadiacus, 

 Dawson [ = Lepidophloios laricinus, Stern.), whose internal 

 structure was described by Sir William Dawson, is 5 inches in 

 diameter, it only shows the primary xylem with the characteristic 

 peripheral corona.^ 



In his Memoir III.- Professor Williamson describes some 

 specimens from Pettycur, near Burntisland, Fife, under the name 

 of Lejndophloios brevifolium, Will, (not Ett.).^ In a footnote he 

 says — " In a letter from Dr. Dawson, dated November 28, 1872, 

 that observer informs me that he regards the Burntisland plant 

 as identical with Lepidodendron Veltheimianum." Professor 

 Williamson further says — " Until the very characteristic macro- 

 sphores of my plant are shown to exist in some of the localities 

 in which the Lepidodendron Veltheimianum is common, I think 

 it best to retain my proposed provisional name."* 



The external characters of the plant, which Professor William- 

 son originally described as Lepidophloios brevifolium, and subse- 

 quently as Lepidodendron brevifolium, are well seen in weathered 

 surfaces of the blocks containing the specimens, and there is no 



^ Quart. Journ. Geol. Soc, Vol. XXII., p. 163, PI. X., fig. 5. 1865. 

 Acadian Geology, 2nd edition, 1868, p. 489, fig. 17li (p. 457). 



-Phil. Tram., 1872, p. 310. 



^ Though originally described as Lepidophloios, Professor Williamson 

 places this plant in Lepidodendron. in his "General, Morphological, and 

 Histological Index," Mem. and Proc. Manchester Lit. and Phil. Soc, 

 Session 1892-93, p. 10. 1893. 



* I.e., p. 310. 



