170 



F1L1CES. 



form a transverse row in such a manner that all the margins of the bundles 

 are towards the sides on which the leaves arise. Here we see the emerging 

 leaf-traces in the form of crescents surrounded by lateral sinuses in the 

 sclerenchyma-sheath, when this is present. In some cases the extremities 

 of the bundle-plates are united together by irregular bridges, the section 

 having passed exactly through a connecting strand. The arrangement is 

 much less regular in stems in which the phyllotaxy presents numerous 

 orthostichies ; here the transverse section shows one or more bundles 

 passing into the leaves, and from this Stenzel would conclude that the 



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FK;. 16. Transverse section of Psaronius Gutbieri, Cda The thick cortex is pierced by numerous adventitious 

 roots. In the centre of the stem are vascular bundle-plates in two lines a little displaced; on one side of them and 

 answering to the gaps between them are the strongly curved bundles of the emerging leaf-traces. From Zittel's 

 Text-book. 



leaves were arranged in spirals and whorls.- But we may more readily 

 refer these differences to the different elongation of the internodes in dif- 

 ferent species. In the case of very short internodes the traces of several 

 leaves would naturally be together on the same transverse section. There 

 is a fine apparently tetrastichous Psaronius to be seen in well-preserved 

 silicified specimens in the British Museum, which would be suitable for the 

 determination of this question and which should be carefully examined. 

 It appears to have come from Brazil, and is said to have been brought by 

 Claussen from the Museum at Rio Janeiro. It is, as far as I know, the 

 only known specimen of a tetrastichous species in a condition to show the 



