ZAMITES. 



87 



developed frond, linear or linear-elliptical, somewhat abruptly 

 narrowed towards the base, but slightly broadened at the actual 

 base of attachment, separate from the rachis by a well-marked 

 articulation. Veins divergent from the base, but for the most 

 part parallel, and diverging at the tip of the segments, which is 

 bluntly rounded. 



In the examination of the fossil fronds in the National 

 Collection, and the comparison of them with the leaves of 

 existing species, I have often been struck with the close corre- 

 spondence between certain forms of Wealden fronds and species 

 of the genus Encephalartos. An inspection of a thoroughly 

 representative collection of the different forms of Encephalartos 

 fronds, such as are to be found in the exceptionally good 

 collection of living and herbarium specimens at the Royal 

 Gardens, Kew, tends to very considerably widen one's conception 

 as to the characters of this recent genus of cycads. The 

 species generally met with in collections are those in which 

 the pinnae are broad and more or less spiny ; but the genus 

 includes various other forms with pinnae of quite a different 

 form, which often bear a striking resemblance to various fossil 

 fronds. As examples of the diversity of leaf form to be met 

 with in this genus, the few following species may be cited as 

 representatives of some of the forms assumed : E. Caffer, Miq., 

 with its stout oval pinnae, with or without marginal teeth, 

 E. pungens, Lehm., with long, narrow, and acuminately terminated 

 segments, E. cycadifolius, Lehm., and E. Ghellinckii, Lern. (PI. 

 XIII. Figs. 3-5), characterized by the long and narrow pinnae, 

 which form a striking contrast to the broader and better known 

 segments of E. horridus, Lehm., and other species. Some of the 

 species, e.g. E. Lehmanni, Lehm., E. cycadifolius, Lehm., and others 

 have a close resemblance to some species of Ceratozamia and Zamia. 



In the introductory remarks mention was made of the institution 

 by Fontaine of a new genus, Encephalartopsis, for certain isolated 

 pinnae from the Potomac beds of North America ; and such a genus 

 might serve a useful purpose if founded on more satisfactory 

 material, but as at present defined it can have but little value. 

 Possibly the institution of such a genus, with a wide and modified 

 definition, might prove a valuable addition to our list of fossil 

 genera, but for the present it will perhaps be better to fall back 

 on the old and comprehensive Zainites. I have ventured to 



