236 Proceedings of the Royal Physical Society, 



No further change took place in the designation of this plant 

 till 1869, when Schimper again placed it in the genus Adian- 

 tites, but restored the original specific name of crassus. 



My attention was specially directed to this fern when going 

 over the fossil plants in the Museum of Science and Art, Edin- 

 burgh. In the " Hugh Miller Collection " were two speci- 

 mens from Burdiehouse, one of which agreed entirely with 

 the description and figure of Sphenopteris Kiowitzensis, Stur ; 

 but on the lower part of the specimen were a few pinnules 

 similar to those on the figure of S. crassa, L. & H. 



From the original plate and description of Lindley and 

 Hutton I could not, however, determine whether the plant 

 described by Stur was a distinct species or only a more perfect 

 specimen of Sphenopteris crassa. 



On searching, I was successful in finding the type of 

 S. crassa, L. & H., in the Museum in connection with the 

 class of Geology in the University of Edinburgh, an examina- 

 tion of which at once showed that the specimens in the 

 '' Hugh Miller Collection," and the S. Kiowitzensis, Stur, be- 

 longed to S. crassa, L. & H. 



The type specimen shows the lower part of a frond, the 

 axis of which bifurcates about an inch above the base of the 

 portion which has been preserved. 



No pinnae are borne on the rachis below the bifurcation ; 

 but on the left-hand side of the left arm of the fork three 

 pinnae are given off (PL Y., Fig. 1). On the right-hand side 

 of the same arm of the fork only one is produced ; but below 

 it we have two large cyclopteroid pinnules, which occupy an 

 analogous position on the stem to that of the pinnae. 



On either side of the axis, below the bifurcation, large 

 cyclopteroid pinnules are also situated, similar to those on the 

 inner side of the left and on the remaining fragment of the 

 ri^ht-hand arm of the bifurcation. 



On the highest pinna, the form of the pinnules changes 

 and assumes a rhomboidal outline, the margins being more 

 or less deeply cleft. 



The rachis shows little scars from which scales have pro- 

 bably fallen. 



On the specimen in the " Hugh Miller Collection," one of 

 the pinnae towards the lower part of the fossil shows the 



