JrUASSIC ('V('Al)S FROM AVYOMING. lilO 



ill organic coiiiioctioii with the trunks to which Ihcv l)elong. And even 

 in this case the evichniee u\Hm which WiUiamson based liis orifjinal 

 rest ofat ion" was foi- many years calle(| in (juestion ])\ most working 

 paleobotanists. 



Count Sohiis-Laui)acli (1887)'' states that the only instance known 

 to him of a cycad witli attached knives that coukl he identified with 

 certainty- was to be seen in a specimen of Willinfnsonid {Zamites) gigas 

 from the Upper Jurassic sandstone of Yorkshii'e, jMiglaiuL This specimen 

 was originally figured by Saporta.' 



Still further examples of more or less full-gi'own fronds of the \A'il- 

 liamsonia type, whose organic connection with stems may lie j)roved, 

 were given by Seward in 1897,'' together with (juite conclusive evidence 

 in favor of the identity of Williamsonia and the cycadean trunks referred 

 to the genus Bennettites of English and Continental paleobotanists. 



Here the subject rested until I announced the discovery of the 

 crown of young leaves with structure preserved in the tjpe of Cycadeoidea 

 ingens Ward.' This was one of the earliest results of the microscopic 

 examination of our superb series of American fossil cycads undertaken 

 by me, an examination which Professor Ward has done so much to 

 encourage. 



Since then many additional facts have been discovered concerning 

 the leaves of the Bennettitacea-, and the forms in various other species 

 determined, but an account of these is reserved for a future extended 

 publication on the entire sul)ject. It is only intended here to describe 

 more briefly the discovery of the leaves in a typical form of Cycadella, 

 this making the third Bennettitean genus in which they have been 

 positively determined, and the second in which both structure and 

 prefoliation are known — that is, if we regard Bennettites and Cycadeoidea 

 as including forms generically distinct. Evidence is accumulating that 

 such is the fact. 



« Coiitiil)iiti()ns towards the History of Zamia gigas Lindl. & Hutt., by W. C. Williamson. Trans. Linn. 

 Soc. London, Vol. XXVI, London, 1870, pp. ()(i,'?-()74, pi. Hi, liii. 



b Einleitung in die Paliiopliytologic, Leipzig, 1887, p. 96; Introdnclidn to Fossil Botany, English trans- 

 lation, 1891, p. 94. 



« Paleontologie fran(;aiso, Plantes Jurussi(|Ufs, Vol. II, Paris, 1873, p. 56, pi. lxx.\i, fig. 1. 



<lOn the leaves of Bennettites: Proc. Ciirnhridge Phil. Soc., Vol. IX, Pt. V, March S, 1897, pp. 273-277. 



I" A study of some American fossil cycuds: Part II, The leaf stnictnreof cvcudeoidca: .\m. .Journ. Sci., 

 4th ser., Vol. VII, April, 1890, pp. 30.>-30S, pi. vii. 



