XXVIl] 



GLOSSOPTERIS 



507 



tion. The arbitrary separation of sterile leaves, which differ by 

 small degrees from one another in form and in the details of 

 venation, by the application of specific names is a thankless 

 task necessitated by custom and convenience ; it is, however, idle 

 to ignore the artificial basis of such separation. Mr Arber has 

 recently published, in his valuable Glossopteris Flora, an 

 analytical key which serves to facilitate the description and 

 determination of different types of frond ^. 



The large leaves of Glossopteris indica, reaching a length in 

 extreme cases of 40 cm. and a breadth of 10 cm., are characterised 

 by a rather greater regularity in the arrangement of the 



Fig. 341. Glossopteris indica, Schimp. ( x IJ.) From Arber, after Zeiller. 



meshes and by the greater parallelism of the upper and lower 

 sides of each mesh (fig. 341) and by less difference in size 

 between the venation meshes than in G. Browniana, the leaves 

 of which are usually smaller. The relatively thick epidermis 

 consists of rectangular cells with stomata in depressions 2. 

 The scale-leaves ^ rather larger than those of G. Browniana, 

 are more or less rhomboidal with rounded angles and reach 

 a length of 1-5—6 cm. and a breadth of 1'.5— 2-5 cm. The 

 rhizome is practically identical with that of G. Broivniana*. 



This species occurs in great abundance in the Permo- 

 Carboniferous rocks of India, Australia, and in various parts of 



1 Arber (05) p. 47. 

 3 Zeiller (02) ; (03). 



'^ Zeiller (96) A. p. 868, fig. IS. 

 * Oldham (97). 



