388 



FILICALES 



[CH. 



lower end and gradually tapered distally. The lamina, 3—14 cm. broad, 

 is characterised by obtusely pointed marginal lobes. From the midrib 

 of each pinna lateral veins are given off at a wide angle, and adjacent 

 veins are connected by a series of branches which divide the lamina 

 into a regular reticulum of rectangular and polygonal meshes (fig. 285). 

 The aori are abundant and contain 5—12 sporangia like those oi Dictyo- 

 phyllum. 



C- 



FiG. 286. Clathropteris egyptiaca. 

 grooves. 



(Nat. size.) a, b, pieces of maiu ribs in 



What is probably the rhizome of this species has been 

 described by Nathorst (Rhizomopteris cruciata) ; it is similar 

 to that of Dictyophyllum, but the leaf-scars are more widely 

 separated. This species occurs in Upper Triassic, Rhaetic or 

 Lower Jurassic rocks of Scania, France, Germany, Switzerland, 

 Bornholm, North America, China, Tonkin, and Persia and is 

 represented by fragments in the Rhaetic beds of Bristol \ 

 1 Seward (04) pp. 18, 164. 



