118 TEUNCI. 



petiole bases. An example of such resemblance is afforded by 

 a specimen figured by Hosius and von Marck as probably Proto- 

 pteris punctata, Sternb. ; the plant represented in their plate xliii. 

 fig. 186 : might well be described as an imperfect cycadean stem. 

 Again, it is almost impossible in some cases to decide with 

 certainty between an imperfect cone and a small cycadean stem. 

 The fossil described by Lesquereux from Colorado as Zamiostrobus 

 mirabilis, 2 is obviously a badly preserved stem with basal portions 

 of petioles. An examination of such a stem as that of the living 

 species of Cycas, is sufficient to demonstrate the difficulties 

 attending our attempts to separate into specific forms fragments 

 of imperfect stems. The upper part of an old Cycas stem with 

 its bud scales still in place, presents a very different appearance to 

 the lower portion of the same axis, from which the scale leaves and 

 petiole bases have become detached, leaving clean-cut rhomboidal 

 scars. As a general rule we have a fairly easy task in identifying 

 fossils as cycadean stems. The frond scars and scale leaves which 

 clothe the woody axis afford a convenient distinguishing feature ; 

 but, on the other hand, it is important to keep in view the existence 

 of other forms of stems among recent cycads, in which the well- 

 known covering of leaf bases is absent. In such plants as Zamia 

 Loddigesii, Miq., and Z. Skinneri, "Warsz., the peculiar branched 

 stem, with its transversely elongated wrinklings and small knob- 

 like protuberances, presents a totally different aspect to the trunks 

 of Cycas, Encephalartos, Dioon, and others. It may be noted 

 in this connection that the Lower Greensand fossil which Kouig 

 named Dracaena Benstedtii? and of which the National Collection 

 contains several examples from the Kentish Rag of Maidstone, 

 and a few recently added by Mr. Rufford from the Ecclesbourne 

 Wealden Beds, shows a striking resemblance to the stems of the 

 0bove-named forms of Zamia. The fossils have at all events no 

 claim to a generic name implying a monocotyledonous affinity. 



We cannot here undertake a descriptive account of the 

 morphology of recent cycadean stems ; but for information on 

 this head, reference may be made to the treatment of these 



1 (A. 1), Palseontographica, vol. xxvi. 

 Lesquereux (1), p. 70, pi. Ixiii. fig. 1. 

 3 Morris (A), Brit. Foss. p. 8. 



