16 CTCADACE^:. 



or opposite arrangement of the pinnae, (vi.) The form of the 

 epidermal cell-walls, (vii.) Presence of spines on the segment 

 margin. In addition to these more detailed characters, the form 

 of the frond as a whole, whether simple, pinnate, or bipinnate, 

 and the shape of the individual pinnae, long, narrow, broadly 

 oval, etc., are important characters to be kept in view. 



In Goppert's valuable paper on fossil cycads, 1 the wholesome 

 warning is given that to define generic characters within such 

 narrow limits as are often adopted, results in an unnecessary 

 multiplication of genera, and tends to confusion and to increase 

 the difficulties of determination. Allusion has already been made 

 to the numerous leaves, the affinities of which cannot be definitely 

 settled until further data are forthcoming. As regards the genus 

 Nilssonia, some writers have argued for its inclusion among ferns, 

 but others prefer to consider it an unusual form of cycadean 

 frond. Tceniopteris, Neuropteris, Noeggerathia, and a host of other 

 leaves must for the present be left in a somewhat doubtful 

 position. The genus Stangerites, instituted by Bornemann, 2 has 

 been iised by a few authors as a convenient term for certain 

 Tceniopteris-like leaves, but the name seems unnecessary, and 

 may be ranked among those misleading titles which suggest a 

 relationship to a living genus which is not supported by facts 

 of any taxonomic value. Saporta, in speaking of this genus, 

 remarks that the author of the term Stangerites " a ajoute a ce 

 qui s'etait fait avant lui une confusion reellement inextricable et 

 perisse de difficulties la synonymic des principales especes, decrites 

 d'apres leurs feuilles seulement." 3 



In the recent species Stangeria paradoxa (Moore), it is worthy 

 of note that we have pinnae with entire margins, and others with 

 deeply cut lobes extending to the midrib ; some of the deeply 

 divided laminae suggest in a slight measure a Nilssonia form of 

 leaf. In a small plant of Ct/cas circinalis, L., in the Royal 

 Gardens, Kew, I noticed an abnormal form of leaf structure at 

 the base of a young frond, suggesting another example of an 

 approach to the Nilssonia type of leaf. Instead of the ordinary 

 uuinerved and separate pinnae characteristic of Ct/cas, this 



1 (1),P- 116. 



2 p. 58, misspelt " Strangerites, nor. gen.' 



3 Loc. ctt. p. 39. 



