12 CYC AD ALES [CH. 



palaeobotanical student of the occurrence of flowering plants 

 with stems closely simulating those of some Cycads. Prof. Bower 1 

 in describing Rhynchopetalum montanum, an Abyssinian Lobelia- 

 ceous plant, drew attention to the similarity in surface-features 

 and to some extent in anatomical structure to cycadean stems. 

 The resemblances are further emphasised in a more recently 

 published account of the same species under a different name, 

 Lobelia Rhynchopetalum 2 . 



FIG. 383. Cycas siamensis. (From the Encyclopaedia Britannica.) 



Fronds. A general acquaintance with the various types of 

 fronds illustrated by recent Cycads is important to the student 

 of fossils not only to enable him to compare existing and extinct 

 forms but as affording safeguards against possible sources of error 

 in the description and identification of impressions 3 . The verna- 

 tion exhibits less uniformity than in Ferns: in Cycas the rachis 

 is straight and the pinnae circinately coiled (fig. 220, B, vol. n. 

 p. 283) ; in Zamia and Stangeria the rachis is bent and the pinnae 

 straight, while in Ceratozamia and other genera both the axis 

 and leaflets are straight. As Braun pointed out, there is as a 

 rule no terminal leaflet, or it may be pushed to one side giving 

 a forked appearance to the frond apex 4 . 



1 Bower (84). 2 Rosen (11). 



3 Seward (95) A. pp. 15 et seq. 4 Braun, A. (75). 



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