78 



MISS NELLIE BANCEOFT ON SOME 



centrifugal xylem; tlie pliloem also is indistinguisliable (PL 9. fig. 9), Between the 

 leaf -bases are indications of ramental hairs (PL 7. fig. 18). 



The cortex of the stem is fairly wide, and has many secretory sacs (PL 8. fig. 14). A 



■ 



tissue suggesting periderm is developed more or less irregularly in its inner layers 

 (PL 8. figs. 10 & 13). Traces of leaf-supply strands are seen here and there (fig. 10), 

 hut it is impossible to obtain any idea as to their course. Phloem and cambium are not 

 preserv^ed. The wood is fairly compact, with numerous uniseriate medullary rays, and 

 is of almost coniferous appearance (PL 8. figs. 9-12; cf. 27, p. 193; Zl^ P- 75, fig. 41). 

 The xylem elements themselves are small and radially arranged. The radial longitudinal 

 section of the upper part of the stem-fragment shows very occasional indications of 

 tracheides with bordered pits arranged similarly to those of recent Gycads, as noted by 

 Oldham and Morris (PL 8. fig. 15; see 19, p. 35). The wood, although much broken 

 up, with a certain amount of separation into rings, appears to have been developed 

 originally in a single continuous zone, the primary cambium having persisted. The 

 breaking up of the xylem zone (PL 8. fig. 10) may have been occasioned by the conditions 

 of preservation, or, as Oldham and Morris suggest (19, p. 35), by "the partial decomposi- 

 tion of the wood previously to its becoming mineralised." A similar appearance in an 

 Indian cycadean stem is figured by Seward in his * Catalogue of Mesozoic Plants ' 

 (27, p. 194, text-fig. 30 B). 



The structure of the woody zone is undoubtedly endarch (PL 8. fig. 12 ; cf. 37, p. 75, 

 fig. 41 d). The pith is parenchymatous with numerous secretory sacs, such as those in 

 the medulla of Cycadeoidea (37, p. 77) ; there are no medullary vascular strands. 



Tliis stem possesses characters some of which are cycadeoidean, while others point to 

 contact AV'ith the recent Cycads. The endarch nature of the xylem is common to all 

 Cycadophyte stems, but the single compact woody zone with its narrow medullary rays 

 is a characteristic feature of the cycadeoidean stems, wholly different from the looser 



of recent cycadean wood, formed 



from successive cambiums 



The Indian stem has multiseriately pitted tracheides similar to those of Cycads, as con- 

 trasted with the scalariform type usually occurring in the Cycadeoidese (37, p. 75). Like 

 these, however, it has numerous secretory sacs in its parenchymous ground-tissues, 

 rather than the gum-canals of recent Cycads. So far as external characters are 

 concerned, the stem described resembles that of a recent " armoured " Cycad in general 

 appearance, for the leaf-bases, unlike those of the Cycadeoidese, do not possess axillary 

 structures; while in place of the ramental scales figured by Wieland (i^y) for his 

 American Cycadeoidese, and by Seward (25) for the English type Cycadeoidea gigantea, 

 the leaf-bases are separated by a packing of ramental hairs. 



In the structure of the xylem and medullary rays, and of the leaf-bases wdth their 

 ramental hairs, the Indian stem agrees with the axis of Prof. Seward's Scottish 

 WilUmnsonia fructification *. The leaf- and bract-bases in the two forms show exact 

 correspondence in shape and size, in the amount of sclerenchyma and character of the 

 ground-mass, and in the number and nature of the vascular bundles. 



* Prof. Seward 

 vol. 203, p. lOlJ. 



a full account of this specimen (see Phil. Trans. Eoy. Soc. ser. B, 



