FOSSIL FLORA OF THE STAFFORDSHIRE COAL FIELDS. 79 



accepted as Sphenopteris trifoliolata is not the Sphenopteris trifoliolata of Artis, but, 

 I believe, only a form of Sphenopteris obtusiloba Brongt. The true Sphenopteris 

 trifoliolata Artis does not seem to have been found outside of England. 



That portion of his table which refers to the plants under discussion is given here :— 



Sphenopteris Schumanni. 

 Pinnules convex, round. 

 Pinnule upper surface smooth. 



Nervation standing out in prominent relief. 



Rachis with broad furrow. 

 Rachis smooth. 



Sphenopteris obtusiloba. 

 Pinnules flat, round. 

 Pinnule upper surface covered with close 



radiating striations. 

 Nervation scarcely visible, generally obscured 



by the radiating striations. 

 Rachis flat without furrow. 

 Rachis with numerous transverse bars. 



With the object of studying this question, through the kind offices of Dr Gothan 

 I received from Dr A. Franke, Dortmund, examples of Sphenopteris Schumanni from 

 Zeche Gluckauf Tiefbau, near Dortmund, the same locality as that from which the 

 specimens figured by Dr Gothan in his pi. iii. figs. 1, 2 were derived. I am also 

 indebted to Dr Beyschlag, Director of the Konigliche Geologische Landesanstalt, 

 Vienna, for kindly sending me for examination a specimen of Sphenopteris Schumanni 

 from the collection under his charge. I cannot therefore be mistaken as to the plant 

 identified by Stub, and Gothan as Sphenopteris Schumanni, and in fact my own 

 collection, under the name of Sphenopteris obtusiloba Brongt., contains specimens that 

 would be named Sphenopteris Schumanni by those who uphold this as a species. I find 

 myself, however, unable to regard Sphenopteris Schumanni as specifically distinct, for 

 among the specimens I have examined I find that the supposed distinctive characters are 

 not constant, and are apparently due in part to causes attending their fossilisation. 



If one now considers these supposed specific differences, first, as to the pinnules 

 being convex in Sphenopteris Schumanni and flat in Sphenopteris obtusiloba, it will be 

 found, I think, that this depends entirely on the amount of pressure to which the 

 fossils have been subjected. On the specimen of Sphenopteris Schumanni from Buhen 

 Grube near Neurode, 7 Flotz, kindly lent me by Dr Beyschlag for examination, at one 

 side of the slab a few of the pinnules are more or less convex, while on the other side some 

 of the pinnules are quite flat and the rachis is perfectly smooth without any trace of the 

 " broad furrow," this condition of the specimen being evidently the result of pressure. 



On the example of Sphenopteris obtusiloba figured in the Trans. Roy. Soc. Edin., 

 vol. xxxvii. pi. i. fig. 1, # the pinnules are flat and the nervation well shown on account 

 of the striated epidermal surface having been removed from all the pinnules except 

 at one or two points. The rachis here is also smooth and shows no trace of the trans- 

 verse bands which are one of the distinctive characters of Sphenopteris obtusiloba. The 

 surface striation of the pinnules is caused by the arrangement of the epidermal cells. 



It is seen, then, that the characters said to be available for the separation of 

 Sphenopteris Schumanni Stur from Sphenopteris obtusiloba Brongt. are most 



* "On the Fossil Plants of the Kilmarnock, Galston, and Kilwinning Goal Field," p. 307, pis. i.-iv. 



