xxi] 



DIPTERIDINAE 



391 



Hausmannia may be defined as follows : 



Rhizome creeping, slender, dichotomonsly branched ; leaf-stalks slender 

 (2 — 25 cm. long), bearing a leathery lamina (1—12 cm. long and broad), 

 wedge-shaped below, occasionally cordate or reniform, entire or more or 



Fig. 288. Hausmannia dichotoma. (Specimens from the late Dr Marcus Gunn's 

 Collection of Upper Jurassic plants, Sutherlandshire ; very slightly 

 reduced.) 



