THE VICTORIAN NATURALIST. 



In a typical Glossopteris leaf this primary vein or midrib is not 

 formed by the gradual coalescence of the basal portions of the 

 secondary veins, but consists of an apparently definite vascular 

 bundle, very strong at the leaf base, and more or less gradually 

 tapering to the apex. 



The generic distinctions between leaves of the Gangamopteris 

 and Glossopteris types are based on very slight characters; 

 and in illustration of this point I may quote the recent re- 

 marks by Mr. A. C. Seward* in a work received during the 

 writing of these notes. On page 2 of the work referred to 

 below, Mr. Seward says : — " There can be no doubt that the 

 recognized distinction — namely, the absence of a true midrib — 

 between Gangamopteris and the slightly better known genus 

 Glossopteris is a character which cannot be recognized as one of 

 great taxonomic importance. Several authors have referred to 

 the difficulty of drawing a satisfactory distinction, in certain cases, 

 between these two genera, and there can be little doubt that the 

 simple leaves, which it is customary and convenient to designate 

 by the name Gangamopteris, are those of a fern which was closely 

 allied to Glossopteris. We cannot assert with confidence that the 

 fossils described under the two names are generically distinct, but 

 it is convenient to retain both terms, particularly as the leaves 

 without the midrib appear to have a range in time somewhat 

 different from those with a well marked median rib." In con- 

 nection with our specimen, it is also noteworthy that Mr. Seward 

 has figured and described t an elongate form of Gangamopteris 

 with a similar, but wider, pseudo-midrib, formed of more or less 

 parallel veins only occasionally anastomosing. 



Another eminent palseobotanist, Mr. Newell Arber, expresses 

 a similar opinion to the above, remarking that " since the dis- 

 covery of the scale-leaves of Glossopteris, the presence of a mid- 

 rib is no longer a necessary characteristic of that genus. It is 

 therefore, in the absence of all knowledge of the fructification of 

 either type, extremely doubtful whether the genus Gangamopteris 

 should not be merged in Glossopteris." t 



Description of the Specimen. — The rock in which our 

 specimen is preserved — a soft, friable sandstone — is hardly suited 

 for the close and critical examination necessary for the deter- 

 mination of the relation of the secondary veins to the sulcus. I 

 have, however, compared it with better preserved examples of the 

 same type of leaf from Bacchus Marsh, in the collection of the 

 National Museum, where there are several specimens of undoubted 

 Gangamopteris leaves exhibiting a median groove. This groove 



* Mem. Geol. Surv. India (Palreontologia Indica), vol. ii., Mem. 2, 1905. 

 t Loc. supra cit., p. 3, plate viii. , figs. 1-6 ; plate ix., figs. I, 2. 

 J Quart. Journ. Geol. See, vol. Iviii., 1902, p. 14. 



