INDIAN JUEASSIC GYMNOSPEEMS. 



75 



p. 59, figs. 30 & 33). In vascukr bundle arrangement, tlic present examples agree 

 witli the majority of Wieland's Cycadeoidean racliises, which, he points out, show a fern- 

 like V-shaped or closed grouping of the bundles (37, p. 62), characteristic of "a pinnular 

 bundle supply arising from the upper sides of the system" producing closely-set pinnules 

 as in Ftilo2:)hyllum and Otozamites, while the omega type of bundle arrangf^mcnt 

 of most recent Cycads " results in a heavy continuous ridge between the two rows of 



pinnules " (p. 63). 



Nothing can be determined from longitudinal sections with regard to the nature of 

 the xylem elements; indeed, in most sections, longitudinal or transverse, it is difficult 

 to distinguish any vascular tissue at all. Nor can the rachis sections be referred with 

 certainty to either Ftilophjllum or Diotyozamiies, except in one case where a transverse 

 section sliowing the U-shaped vascular arrangement is definitely correlated with an 



impression of a JPtilophyllum leaf. 



Where the attachment of the pinnge with the rachis is seen in section, it is clear 

 that in some cases the pinnie are much more closely-set than in others ; this condition 

 probably corresponds wdth greater approximation of the arms of the vascular system, as 

 some of the sections seem to suggest (PL 8. fig. 18 « & h). It appears possible from 

 examination of the fronds on the surfaces of the blocks that the less closely set 

 examples are Dictyozamites, but no essential difiCTcnce of bundle arrangement can be 



detected. 



In none of these cases of pinna-attachment is it possible to obtain a clear idea of 



pinna structure. In an example of FtllophyUum cutchense lying at the surface of 

 block II., however, the structure, as far as can be determined, shows an upper small- 

 celled epidermis, with possibly an upper hypoderm, palisade and spongy mesophyll with 

 vascular bundles not showing structure, and a lower epidermis, well-marked but not 

 sufficiently clear to show^ stomata (PI. 8. fig. 4iakb; see also PL 9. fig. 6). ^ The 

 pinna? decrease in thickness somewhat abruptly towards the margin and appear pomted 

 in transverse section. It is possible, however, that this is a variable character. 



Other pinnte present in the sections, though of essentially the same structure as those 

 of Ftllophyllmn cutchense, were evidently originally thinner in texture. Further, 

 they possess relatively a greater number of vascular bundles, whHe the pinna-margins 

 are decidedly rounded (PL 9. fig. 5). In the pinna of this type figured, each vascular 

 bundle is seen to possess a small mass of xylem presumably centrifugal ni nature; for 

 adjacent to this xylem, above and below, are cavities representing, no doubt, centripetal 

 xylem and protoxylem towards the upper surface of the leaf, and phloem towards the 

 lower surface (PL 8. fig. 7). Pimi^ of this second type may be tentatively referred to 

 Dictyozamites falcatus, since the external characters of this species suggest a closer 

 correspondence with the structure as seen in section than do those of Ftdopliyllum 

 acMtifolium. 



There can te little doubt with regard to the cycadeaii affiaitios of these fronds. Both 

 types are cycadean in general plau, agreeing with such recent Oyoads as some of the 

 Zamias, which show palisade mesophyll. In the possession of paUsadc tissue there is 

 agreement with Ci/cadeoidea ini/ens, "Ward (35, pi. 7. fig- ^)- 



