XXl] DIFTERIDINAE 389 



Glathropteris egyptiaca Sew.^ Fig. 286. 



The specimen on which this species was founded was dis- 

 covered in the Nubian Sandstone east of Edfu ; the age of the 

 beds is uncertain, but the presence of Glathropteris suggests a 

 Lower Jurassic or Rhaetic horizon^. Seven strong ribs radiate 

 through the lamina from the summit of the petiole ; at a and b 

 small pieces of the projecting ribs are shown in the grooves. 



Fio. 287. Camptopteris spiralis. (After Nathorst. Much reduced.) 



From the main veins slender branches are given off at right 

 angles and, as seen in the enlarged drawing, these again sub- 

 divide into a delicate reticulum with free-ending veinlets. 



Camptopteris. 

 Camptopteris spiralis, Nath. Figs. 282, C; 287. 



Nathorst proposed this generic name for Rhaetic fronds' 



1 Seward (07). 



2 The evidence of the shells is stated by Mr B. B. Newton (09) to be in 

 favour of the Cretaceous age of the Nubian Sandstone. 



3 Nathorst (78) p. 33. 



