244 CORDAITEAB [CH. 



cuticles of some Indian specimens, sent to Cambridge by the 

 Director of the Indian Geological Survey, and a comparison of 

 them with preparations made from European Cordaites leaves, have 

 revealed certain distinguishing features which support Zeiller's 

 view that the Gondwana-Land leaves, though similar superficially 

 to those of Cordaites, are probably distinct. It is, however, 

 impossible in many cases to obtain any information with regard 

 to epidermal characters, and though it would seem probable that 

 had we a fuller knowledge of the Indian and southern hemisphere 

 plants represented for the most part by leaf-impressions well- 

 defined distinguishing features would be recognised, the compre- 

 hensive name Cordaites may conveniently be retained on the 

 ground that in the absence of well-preserved cuticles no satis- 

 factory distinguishing features are exhibited by the impressions 

 of Noeggerathiopsis. 



Phylladoderma. Zalessky. 

 Phylladoderma Arberi Zalessky. 



Zalessky^ founded this genus on some Permian leaves from the 

 Petschora basin (Adzva River) which closely resemble those of 

 Cordaites but are characterised by a coarser venation. The 

 lanceolate lamina reaches a length of 18 cm. and a breadth of 

 4-2 cm. ; the veins are 2 mm. apart and occasionally forked near 

 the base of the leaf. The epidermal cells have straight waUs and 

 stomata are abundant on the lower surface. As Zalessky says, 

 the systematic position of the leaves is uncertain though they are 

 probably Cordaitean. The coarseness of the venation is a feature 

 of minor importance and hardly worthy of generic recognition. 



Rhiptozamites Schmalhausen. 



This genus was instituted by Schmalhausen^ for leaves from 

 beds in the Kusnezk basin regarded by him as Jurassic. These 

 strata are now recognised as Permian* and homotaxial with those 

 from which Schmalhausen* subsequently recorded the same 

 species. The leaves, though smaller than many of the Indian 

 and South African specimens of Cordaites (Noeggerathio-psis) 



1 Zalessky (13) p. 23, Pis. i. fig. 4; n. figs. 7, 9; m. figs. 3, 5—8, 10, 11. 



2 Schmalhausen (79) A. p. 29. s ZeiUer (96) A; (02). 

 * Schmalhausen (87) B. p. 37. 



