CYCADACE^E. 



As a general rule, the fronds of recent cycads are simply 

 pinnate ; but in the Australian genus Bowenia, 1 with its bipinnate 

 leaves, we have an exception to this rule ; and it is by no means 

 improbable that this character may have been shared by many 

 extinct genera. The late Dr. Stur, of Vienna, expressed his 

 belief that the well-known Coal-Measure fossils Neuropteris and 

 Alethopteris should be included in the list of Palaeozoic cycads, 

 and this opinion was partly founded on the resemblance of the 

 Carboniferous fronds to the branched leaf of JBowenia. The absence 

 of any clearly proved fructification in these so-called ferns has 

 been referred to by Stur and others in favour of a cycadean 

 relationship. Kidston 2 has recently recorded the occurrence of 

 a fertile Neuropteris frond, but the facts he publishes cannot be 

 regarded as finally settling the position of these genera. He 

 figures a terminal portion of a specimen "ending in a number of 

 dichotomous branchlets, the ultimate divisions being about 8 mm. 

 long, and bearing the fruit at their summits." Unfortunately the 

 very small pinnules associated with this fragment do not furnish 

 all the evidence one could desire as to the real nature of the 

 specimens. 



Another aberrant form of a recent frond is afforded by the 

 Australian cycad Hacrozamia heteromera, Moore, 3 in which the 

 pinnae are in some varieties of the species repeatedly forked, 

 reminding one to some extent of the Mesozoic species of Baiera, 

 Specimens of Macrozamia heteromera, var. Na/rrabri, and var. glauca, 

 in the Eoyal Gardens, Kew, show very clearly this striking and 

 unusual character in cycadean fronds. (PL XIII. Tigs. 1 and 2.) 



A further variation in the form of cycadean leaves is seen in 

 such species as Zamia Skinneri, Warscew, Z. picta (=.Z. muncata, 

 Willd.), 4 Z. Wallisii, A. Gr., etc. : the pinnas of these forms reach 

 an unusually large size, and differ in shape from those of most 

 members of the family. A single pinna of Z. Wallisii in the Kew 

 Herbarium measures 37 x 13 cm.; the lamina is traversed by 

 a few prominent and forked veins, and exhibits another peculiarity 

 in the possession of a short petiole. If we have to rely on leaves 



1 Hooker, Bot. Mag. PI. 5398, vol. xix. [3] 1863. 



2 Kidston (1), p. 150, pi. viii. fig. 7. 



3 Moore, p. 122. 



De CandoUe, p. 541. 



