XXVIl] GANGAMOPTERIS 513 



absence of a midrib. Gangamopteris leaves are on the whole larger than 

 those of Glossopteris ; many of them reach a length of 20 cm. and some of 

 the large Indian fronds are nearly 40 cm. long. The venation of Oangam- 

 opteris shows a greater uniformity in the size and shape of the meshes 

 than that of Glossopteris. The middle of the lamina, especially in the 

 lower part, is occupied by a few vertical veins from which branches curve 

 upwards and outwards towards the edge of the lamina. The secondary 

 veins are connected by frequent anastomoses and agree very closely with 

 those of Glossopteris. The lamina becomes narrower towards the base, 

 which is either cuneate or in some cases slightly auriculate (fig. 345). 



As I have elsewhere pointed out\ the presence or absence 

 of a midrib is not in itself a character of real taxonomic 

 importance. In the recent fern Scolopendrium vulgare the 

 frond has a prominent midrib, while in S. nigripes there is no 

 median rib. Mr Arber has expressed the opinion that "it is 

 extremely doubtful whether the genus Gangamopteris should 

 not be merged in Glossopteris "." The retention of the two names 

 is, however, convenient, and it would tend to confusion were 

 we to carry to its logical conclusion the view that the recognised 

 distinction between the two genera may not be a mark of 

 generic difference. 



Gangamopteris is confined to Palaeozoic strata, a fact which 

 leads White ^ to speak of the Gangamopteris rather than of the 

 Glossopteris Flora. It occurs in South America, South Africa, 

 Australia, and India, extending as far north as Kashmir; it has 

 been discovered by Amalitzky in Permian rocks of Eussia*. 

 The Russian rocks in which Glossopteris and Gangamopteris 

 were found are no doubt of Permian age. In Australia, South 

 Africa, Brazil and Argentina, and in the Indian Coal-fields, 

 Gangamopteris is a characteristic genus of Lower Gondwana 

 rocks. These strata are usually spoken of as Permo-Carbon- 

 iferous in order to avoid the danger of attempting on insufficient 

 data a precise correlation with European formations. 



Feistmantel speaks of Gangamopteris as most abundant in 

 the Talchir-Karharbari beds, though it is represented also in 

 the overlying Damuda series. In Australia the genus occurs in 

 rocks which correspond in position and in their plant fossils 



1 Seward and Woodward (05) p. 2. 



2 Arber (02") p. 14. ' White, D. (07). ■* Arber (05). 



