CARBONIFEROUS LYCOPODS AND SPHENOPHYLLS. 59 



diameter, the vascular axis being slightly over 1J inches in 

 diameter, of which the secondary xylem measures ~ of an inch 

 and the primary xylem -J^- of an inch in thickness. The structure 

 of the vascular axis and outer bark is beautifully preserved. All 

 these species of Lepidophloios, to which genus this fine specimen 

 from Dalmeny evidently belongs, show certain characters which, 

 though perhaps not restricted to Lepidophloios, appear to be more 

 pronounced in that genus than in Lepidodendron. These are 

 the little points of small tracheides which jut out from the 

 periphery of the primary bundle, forming what has been called 

 the " corona" and the late period at which the development of 

 secondary xylem occurs. 



A secondary development of " tissue " 1 has been observed in 

 Lepidophloios fuliginosus, termed by Williamson "a very rudi- 

 mentary form of secondary xylem strand," 2 and a strongly- 

 developed secondary xylem occurs in Lepidophloios Wunschianus 

 and in the Dalmeny specimen, where it forms a thick zone. 



There is strong reason to believe that the Lepidodendron 

 Harcourtii, Witham, is also a Lepidophloios. It has all the 

 peculiarities of the genus, and I feel strongly inclined to place it 

 provisionally in Lepidophloios. One of the characters which, 

 according to Williamson, distinguishes Lepidophloios Harcourtii 

 from his Lepidophloios fuliginosum is the presence of a diploxy- 

 loid leaf-trace in the former. Mons. Bertrand, 3 and more 

 recently Seward, have examined the leaf-traces of Lepidophloios 

 fuliginosum, and found that in structure they are identical with 

 those of LepAdophloios Harcourtii, Will. sp. (With. ?). What 

 were previously supposed to represent a strand of bast fibres is in 

 reality a strand of laticiferous tubes. 4 Whether this laticiferous 

 tissue may have performed the functions of the bast elements is 

 uncertain. 



1 Seward, Leptidophloios fuliginosus. Proc. Camb. Phil. Soc, Vol. X., 

 Partiii., p. 140, 1S99. 



2 Williamson, "General, Morph., and Histol. Index," Part ii. Mem. 

 and Proc. Manchester Lit. and Phil. Soc, Session 1892-93. Ser. IV., Vol. 

 VII., 1893, p. 13. 



3 Remarques sur U Lepidodendron Harcourtii de, Witham, p. 119. 1891. 



4 Seward, '-'Notes on the Binney Collection of Carboniferous Plants — I. 

 Lepidophloios." Proc. Camb. Phil. Soc, Vol. X., Part hi., pp. 140-141. 

 1899. 



