CTCADOLEPIS. 95 



In the genus Ceratozamia the expanded base of a frond shows 

 two lateral stipule-like appendages, aud these are also found in 

 the same position on the margin of the smaller scale leaves. 1 In 

 some forms of Macrozamia, the surface of an old stem is entirely 

 enclosed in a thick armour of large persistent petiole bases without 

 any accompanying scales. Many recent cycadean stems appear 

 to be covered by numerous scale-like structures of identical form ; 

 it is by no means an easy task in many cases to distinguish 

 between the bases of true fronds and those of scale leaves, even 

 where both forms of leaf are present. The variation in form 

 and size exhibited by the scale leaves of recent species, sufficiently 

 demonstrates the futility of attempting any exact generic or 

 specific discrimination in the case of the isolated fossil examples. 

 It is true we have in Dioon and Cycas fairly characteristic lanceo- 

 late scales, often clothed in a dense woolly covering; but a close 

 inspection of a tall stem of the latter genus reveals a marked 

 difference in the scale leaves towards the apex of the stem, and 

 those in the older portions, where there are only the persistent 

 broad bases adhering to the plant stem. In dealing with fossil 

 scale leaves it will probably be wise to extend the definitions of 

 Saporta's genus and to include in it not merely the "elongate 

 lanceolate-acuminate " forms of bud scales, but also other forms 

 of true scale leaves, as well as those structures which may be 

 regarded as the persistent bases of petioles. This genus, used 

 in a much more comprehensive sense, should afford a convenient 

 means of grouping together those detached leaf structures, which 

 frequently cannot be definitely referred to any particular genus 

 or species. Such isolated plant members, in themselves, perhaps, 

 of little value, are worthy of record as contributions to the 

 material from which to build up a more complete history of 

 fossil cycadean plants. Some of the numerous scales in the 

 Kufford Collection may, indeed, be referred to certain forms of 

 stems, and no doubt as our material is increased others may 

 be recognized as portions of some well-defined genus or species 

 of cycad. 



In the male and female flowers of some recent species the 

 detached scales bear a close resemblance to the sterile leaf 

 structures of the stem; it will be well, therefore, to include 



1 Engler and Prantl, Cycadacece, p. 7. 



