508 CYCADOPHYTAN FRONDS [CH. 



valid reason for assuming a relationship with Encephalartos or 

 with any recent type. An impression from Lower Cretaceous, 

 Dakota, beds in Kansas described as Encephalartos cretaceus 

 Knowlt. ex Lesq. MS. 1 consists of a piece of lamina, 9 x 4cm., 

 obovate- oblong and with a cuneate base, a serrate margin and 

 thick diverging veins: the specimen is too incomplete to serve 

 as a record of any Cycadean genus. The generic name Encepha- 

 lartopsis was applied by Fontaine 2 to some imperfect pinnae from 

 the Potomac beds characterised by a linear-elliptical lamina 

 with a spinous margin and slightly diverging and occasionally 

 anastomosing veins. The figured examples of the type-species, 

 E. nervosa, suggest pinnae like those of Ctenis ; but in the absence 

 of a rachis the method of attachment of the segments cannot 

 be ascertained. Saporta 3 named a specimen from the Miocene 

 flora of Koumi, Greece, Encephalartos Gorceixianus because of 

 its resemblance in habit to some species of the recent genus; 

 but the designation Zamites would be more appropriate. Ettings- 

 hausen recorded an imperfect impression of a pinna from Tertiary 

 rocks in Styria as Ceratozamia Hofmanni* although it is by no 

 means certain that the fragment is even Cycadean. The genus 

 Taeniopteris was described in the second volume of this book 

 as probably a Pteridophyte, though of uncertain systematic 

 position: it has, however, been shown by Mr Thomas 5 that the 

 Jurassic species T. vittata was almost certainly borne on a stem 

 with reproductive organs constructed on the Bennettitalean 

 plan. Further research may enable us to fix the position of 

 other species but as yet T. vittata is the only representative of 

 the genus which there is good reason for assigning to the Bennet- 

 titales. 



It is undoubtedly true that Cycadean plants, using the term 

 in a wide sense to include the Bennettitales as well as the Cycadales, 

 bulked largely in Upper Triassic, Rhaetic, Jurassic- Wealden 

 floras; the Bennettitales probably reached their maximum 

 development as regards wealth of form and geographical range 



1 Lesquereux (91) p. 29, PL i. fig. 12. 



2 Fontaine (89) B. p. 174, PI. LXX. fig. 4; PI. LXXI. figs. 3, 4, etc. 



3 Saporta (74); Saporta and Marion (85) p. 116, fig. 61 C. 



4 Ettingshausen (88 2 ) p. 272, PI. m. fig. 10. 



5 Thomas, H. H. (15 2 ). 



