S94 STUDIES IN FOSSIL BOTANY 



2. Cycadaceae. — Side byside with the Bennettiteae, 

 true Cycadaceae, or closely allied plants, probably 

 existed in Mesozoic times, but the evidence for their 

 presence is scanty in the extreme. 



Male cones, of a Cycadean type, have been recorded 

 under the. name of Androstrobus, as, for example, 

 A. Nathorsti, a species from the Wealden of Sussex, 

 described by Professor Seward. 1 The thick axis of 

 this cone bears spirally arranged, more or less triangular 

 scales or sporophylls, I to 1.5 cm. in length. " Towards 

 one end of the specimen the basal part of a scale is seen 

 in surface view, and on it are clearly preserved what 

 are taken to be the outlines of pollen-sacs. . . . The 

 striking regularity with which these impressions are 

 arranged is much more marked than in the pollen-sacs 

 of recent Cycads. On the lower surface of a staminal 

 leaf of Dioon or Encephalartos, we find, on the removal 

 of the pollen-sacs, a fairly distinct reticulate marking, 

 but of much less regularity than in the fossil." 2 

 From the evidence of this specimen and one or two 

 similar fossils, it has been inferred that male cones, 

 not essentially different from those of living Cycads, 

 occurred in Mesozoic floras. The evidence, however, 

 is not wholly convincing, and has been considerably 

 shaken by Professor Nathorst's discovery that a cone 

 originally described by him as Androstrobus Scotti, and 

 referred to Cycadaceae, was in reality a Lycopodineous 

 fructification with megaspores, for which he has now 

 created the new genus Lycostrobus? 



1 Fossil Plants of the Wealden, Part ii. p. 110. 

 " Seward, I.e. p. III. 



3 A. G. Nathorst, " Palaobotanische Mitteilungen, 3. Lycostrobus Scotti," 

 Kongl. Svenska Vetenskaps Akad. Handl. vol. xliii. No. 3, 1908. 



