XXXIIIJ CORDAITES 243 



the lamina tapers gradually from a short distance behind the 

 obtuse apex to a relatively narrow base: in venation and form 

 the leaves are very similar to those of C. principalis and other 

 European and North American species. The specimen from 

 India represented in fig. 472 shows several spatiiulate leaves 

 attached in a close spiral to a branch. As White 1 and Zalessky 

 have shown, the stronger ribs are separated by less prominent 

 striations indicating the presence of two sizes of hypodermal 

 strands. The obvious resemblance between Noeggerathiopsis 

 Hislopi and species of Cordaites has long been recognised and 

 many authors have included Feistmantel's genus in the Cordai- 

 tales 2 . Prof. Zeiller 3 preferred to retain the name Noeggerathiopsis 

 as a precautionary measure, chiefly on the ground that the 

 stomata appeared to be less definitely arranged in rows and more 

 scattered than in the European leaves of Cordaites, and because 

 of the absence of interstitial veins. We have as yet little informa- 

 tion as to the arrangement of the stomata, but in view of the 

 irregularity in stomatal grouping in recent leaves this feature is, 

 perhaps, of minor importance. The presence of interstitial 

 ' veins '" has now been established in Indian 4 and South American 5 

 leaves. In a paper published in 1908 6 the name Cordaites was 

 substituted for Noeggerathiopsis and Zalessky 's recent work 

 supports this step. The description by Zalessky of the ribbing 

 in Goeppert's species Cordaites aequalis from Siberia shows how 

 uncertain and variable a character the venation is even in different 

 parts of the same leaf. 



Cordaites Clerci Zalessky. 



This species (fig. 469, D) was instituted for some small lanceo- 

 late or spathulate leaves from the Petschora basin (Adzva Kiver) 7 

 reaching a length of 6 cm. and a breadth of 1 cm. It is separated 

 from Cordaites aequalis on the ground that the veins are more 

 numerous, as many as 44 in a breadth of 1 cm. 



A recent investigation by Miss Holden 8 of the carbonised 



1 White (08) B. p. 549. , 



2 Arber (03) B. p. 178, gives references to other authors. 



3 Zeiller (03) B. p. 149, PL XL. 4 Zalessky (12). 



6 White (08) B. p. 549. 6 Seward and Leslie (08) B. p. 120. 



7 Zalessky (13) p. 20, PI. n. figs. 46. 



8 The results have not yet been published (September, 1915). 



162 



