360 ME. AETHdE JOHN MASLEN ON THE 



Referring to Williamson's figures of Lejpidostrohus oldhamius *, pi. ix. fig. 58 (C.N. 568) 

 is a transverse section, showing at the centre the relatively small vascular cylinder 

 surrounding a pith ; then a space representing the inner and middle cortex, in which can 

 be seen transverse sections of the sporophyll bundles ; and at the periphery of the axis the 

 dark, somewhat disarranged outer cortex, passing into the radially disposed sporophylls d, 

 bearing the large, bulky sporangia. On PI. XXXVII. fig. 23 of the present paper is 

 shown a photograph of the central structures from the same slide as that figured by 

 Williamson. At m. are the remains of the pith-cells, the pith here being relatively 

 small as compared either with Zepidostrobus Bi^ownii, Schimp. f , or the (a) form of 

 L. oldhamius to be hereafter described ; x. is the xylem cylinder, passing at the periphery 

 into a zone of smaller elements, the latter projecting into points as in Lepidodendron 

 Marconrtii, Witham, and other forms ; l.t\ are leaf-trace (sporophyll) bundles just free 

 from the xylem cylinder and now seen traversing a space from which the softer tissues 

 have disappeared ; i.e. the inner cortex with bundles passing through it, and l.t. leaf- 

 trace bundles contained in a space representing the middle cortex. Here each bundle 

 was evidently collateral in structure, the xylem being at x', a space representing the 

 phloem at p', while a parenchymatous sheath is seen surrounding the whole bundle. 



Returning again to Williamson's figures, pi. 1. fig. 59, another transverse section 

 of the axial structures, shows that while the sporophyll bundle is passing through 

 the dark outer cortex, there is a second empty space external to the parenchymatous 

 sheath before mentioned. The origin of this space cannot be made out from the sections 

 figured by Williamson, but in a longitudinal section (C.N. 1613, see my VI. XXXVI. 

 fig. 10), to be afterwards described, it is seen to arise below the bundle and to be continuous 

 with the middle cortex space. It doubtless corresponds with what has been described 

 as the parichnos in the vegetative leaves. 



In the vertical section of the same cone, also figured by Williamson (pi. 6. fig. 61, 

 C.N. 574), on the left the cone is cut more or less tan gentially, exhibiting the pedicels 

 of the sporophylls h in transverse section, each supporting a sporangium a. On the 

 right the section traverses the cone in an obliquely radial direction and shows that the 

 sporophyll passes outward in an approximately horizontal direction, forming at the 

 periphery of the cone the somewhat peltate extremity b'. The ligule can also be quite 

 weU seen in the slide from which this drawing was made (C.N. 574), although it was 

 not described or figured by Williamson J. 



As Prof. Williamson has pointed out : — " Mr. Binney described and figured the above 

 species twice over : once from the specimens from which my sections were also derived, 

 when he assigned to it the name of Lepidodendron Harcourtii; and again in plate viii., 

 when he gave to it the name of L. vasculare. I am obliged to reject both these specific 

 determinations " §. 



• " Organization," &c., Part XIX. 



t Bower, " On the Structure of the Axis of Lepidosirohus Brownii, Schpr.," Ann. Bot. vol. vii, pL 16. fig. 1. 



X Maslen, " The Ligule in Lepidostrobtts" Ann. Bot. vol. xii. p. 258. 



§ " Organization," Part XIX. p. 28 ; Binney, in Palaeontogr. Soc. 1871, pla. 7 & 8, 



