224 



DE. AGNES AEBEE ON THE 



(2) General Form and Dimensions of the Cone and Sporophyll 



As no longitudinal sections are known, it is impossible to estimate the length of the 

 cone. The maximum diameter of the whole fructification was about 2 cms. and of 

 the axis about 4 mm. However, as no specimens are at present available showing 

 the base of the cone, it is probable that these numbers do not give the full dimensions. 



Towards the apex the cone was of tapering form, and the laminae of the sporophylls 

 extended for some distance above the tip of the axis. Numerous laminae are shown in 

 PI. 27. fig. 52 which passes through the apex of a cone. The outline of the apex, as 

 seen in transverse section, was rendered irregular hy the very prominent bases of the 

 sporophyll pedicels (PI. 27. fig. 50). The vertical height of the sporangia must have 

 been extremely small, since a very slight obliquity in a transverse section — so slight as 

 to be scarcely recognisable in the case of the axial region — is sufficient to make the 

 sporangia appear almost as in tangential section, with the pedicel proximally placed on 

 one side of the cone and distally i)laced on the other side [cf. the sporangia to the upper 

 right-hand side and the lower left-hand side of the photograph, PI. 27. fig. 50). 



The width of the sporophyll lamina at the level of insertion of the ligule is 7 mm. 

 The length of the lamina must have been considerable, judging by the number of over- 

 lapping sporophylls seen outside the sporangia in any transverse section. The unusual 

 development of the sporophyll laminae is the only feature of this cone to which 

 Williamson's description draws attention. He remarks on the " well defined sections of 

 the overlapping free ends of the sporangiophores, which have somewhat the form 

 of similar sections of leaves of Lepidophloios " *, and points out that they are more 

 foliaceous than those of Lepidostrohus Brownii. 



(3) Detailed Structure of the Cone Axis. 



The xylem cylinder of the cone axis does not exceed 0*7 mm. in diameter. It has a 

 large pith, 45 mm. across. The xylem is peculiar in including a relatively small 

 number of metaxylem elements. Williamson does not figure or mention the vascular 

 cylinder, but on examining the section f which he describes, I have found that there 



metaxylem present, only the protoxylem being developed. The lowest 



of 



Cone A } is the one in which we should expect to find the xylem at its fullest develop- 

 ment, since it is cut further from the cone apex than any other section of the species 

 which we possess, but even here the metaxylem is interrupted at intervals, and does not 

 form a continuous hollow cylinder, whereas the small elements of the protoxylem 

 external to it are arranged in an unbroken sheath (PL 27. figs. 50 & 51). The pith, 

 which survives in more than one section, consists externally of delicate coUenchymatous 

 elements and internally of larger cells with firmer walls 

 The inner cortex, when it is preserved, forms 



of thin- walled cells 



PI. 27. fig. 51). The outer cortex is a firm layer, which may reach a thickness of about 

 0*7 mm. between the leaf bases (o.c, PI. 27. fig. 50). 



* WiUiamson, W. C. ('94), p. 27. 



t Brit. Mua. (Nat. Hist.) General Collection, V. 8871. 



t U. C. L. Coll., C. 16. a. 



