38 GLOSSOPTERIS. 



fructifications are quite unknown, and they cannot be referred to 

 any families of recent Filicales. It would perhaps be best to speak 

 of them for the present under the more non-committal designation 

 of Fern-like Plants. 



Genus GLOSSOPTERIS, Brongniart, 1822. 

 [Mem. Mus. d'Hist. Nat., vol. viii, p. 232.] 



Fronds often dimorphic, borne on rhizome-like structures 

 ( Yertehraria). The larger fronds simple, entire, sessile, petiolate, 

 or contracted at the base to a short petiole. Size and shape greatly 

 varied. Spathulate, lanceolate, ovate, linear, etc. Apex obtuse, 

 acute, or emarginate. Midrib well-marked, extending to the apex, 

 or impersistent. Secondary nerves numerous, more or less arched, 

 dividing by dichotomy, and anastomosing to form a network, the 

 meshes of which are polygonal, and more or less elongate. The 

 smaller fronds or scale-fronds varied in size and shape, strongly 

 concave, as regards nervation similar to the larger fronds, but 

 without a midrib. Fructification not known, at present, quite 

 beyond doubt. 



The more important characters by which Glossopteris may be 

 recognised are the simple, entire fronds with a midrib (cf. Gan- 

 gamopteris), and the anastomosing and dichotomising secondary 

 nervation. 



Glossopteris was defined by Brongniart in 1828 ' as follows: — 

 " Fronde simple entiere, plus ou moins lanceolee, retrecie insensible- 

 ment ver sa base ; nervure moyenne large a, sa base, s'evanouissant 

 vers le sommet, et donnant naissance a des nervures secondaires, 

 fines, arquees, oblique, dichotomes, quelquefois anastomees a leur 

 base." The large number of fronds of Glossopteris which have 

 since been described from India and elsewhere in Gondwanaland, 

 have, however, considerably modified this generic diagnosis, and 

 a more extended definition has been adopted here. In particular, 

 the fronds of almost all the known species of Glossopteris possess 

 a reticulate secondary nervation throughout the entire lamina, 

 and are not, as Brongniart thought, reticulate only near their point 

 of origin from the midrib. 



1 Brongniart (28 1 ), p. .J4. 



