88 CYCADEAE, MEDULLOSEAE. 



In the type of Pterophyllum, Brongn., the ribbon-like pinnae, which are 

 all of the same breadth and are obtuse at the extremity, form a right angle 

 with the rhachis, being inserted upon it exactly perpendicularly to it on 

 both its sides, and are often connected with one another by a narrow 

 border ; the nerves run in parallel straight lines. The well-known Ptero- 

 phyllum Jageri, Br. from the Keuper may be mentioned as an example. 

 Certain forms of this type, as P. Schaumburgense, Dunk, from the 

 Wealden are distinguished by very short and broad almost quadratic, and 

 often unequal pinnae, and are known by the name of Anomozamites. 

 To the Pterophyllae belong also, according to Schenk 1 , the remains of large 

 leaves from the Keuper of Raibl in Carinthia which he names P. giganteum ; 

 they were first called Noggerathia vogesiaca by Bronn 2 and ultimately 

 appear in Schimper 3 as Macropterygium. 



In the Zamitae the pinnae articulate with the rhachis and separate from 

 it in certain circumstances, but this is not possible with the Pterophyllae. 

 Their numerous nerves, which sometimes form a single dichotomy, run 

 parallel with one anotherand with the margin of the pinnae,and appearto unite 

 with one another at their extremities to form a marginal nerve, as happens 

 in the recent Ceratozamia. In true Zamitae the pinnules are sharp-pointed at 

 the apex, narrowed and abruptly rounded at the base, and are attached 

 obliquely to the axis which they overlap and cover. In the Podozamitae 

 they are more wedge-shaped, have the upper extremity broad and rounded 

 off, and are said to be attached perpendicularly to the axis. When they 

 are found isolated and detached from the axis, and this appears to be often 

 the case, it is not easy to identify them, and they may be mistaken for 

 portions of other similar elongated parallel-nerved leaves, for those of 

 Phoenicopsis for example, or even for leaf-segments of Baiera and Ginkgo. 

 This is still more true of Rhiptozamites 4 , which is only known in the form 

 of isolated pinnae. The genera Noggerathiopsis, O. Feistm., and Eury- 

 phyllum, O. Feistm., which are also placed with Cycadeae, will be con- 

 sidered again further on with the Cordaitae. Finally, the name Glosso- 

 zamitae has been given by Schimper to certain forms of this type which 

 resemble the Pterophyllae in habit, but must be carefully distinguished 

 from them. Zamites 'Feneonis, Br. 5 from the Upper Oolite, and espe- 

 cially frequent in the Coralline Oolite of the neighbourhood of Lyons, 

 may be mentioned as the best-known species of true Zamitae ; as an 

 example of Glossozamitae I should name Glossozamites Zittelii, Schpr c , 

 and of Podozamitae Podozamites distans, Presl. 7 Numerous figures of 

 leaves of Podozamitae are moreover to be found in Heer 8 and Nathorst 9 . 



1 Schenk (7). 3 Bronn (1). s Schimper 2). * Schmalhausen (1), p. 29, tt. 4, 15. 



8 Ettingshausen {2), t. 3. 6 Schenk (4), t. 8. 7 Schenk '3\ tt. 35, tf, 37. " Heer (5). 



fl Nathorst (3,. 3. 4. 



