124 Proceedings of the Royal Fhysical Society. 



the growth of fossil ferns, yet as none of the figures of circin- 

 ate vernation with which I am acquainted surpass this 

 example, I have ventured to give a short description and a 

 fic^ure of it. 



The fossil is about 3 inches long ; but if we measure the 

 full length of the circinately roUed-up portion as if it were 

 straightened out, it is fully 6 inches in length. The specimen 

 is, however, incomplete at its lower extremity ; so its original 

 size cannot now be ascertained. 



The rachis is thick, and still shows slight traces of the little 

 scales with which its surface was once covered. The inner 

 side of the rachis bears about thirty- three circinately rolled-up 

 pinnse. These show nothing further than the midribs of the 

 pinnules which appear as strongly-defined ridges. There is 

 no evidence in the specimen itself to indicate the species to 

 which it belongs ; but from the occurrence of fragments of 

 Fecopteris polymorplia (Brongn.) on the same slab,^ it probably 

 belongs to that fern. 



The specimen is in the collection of the Geological Survey 

 of Great Britain, to whom it was presented by Mrs Stockhouse 

 Acton. 



My thanks are due to Dr A. Geikie, F.E.S., Director- 

 General of the Geological Survey of Great Britain, for 

 permission to describe this interesting fossil. 



Position and Locality. — From the Coal-measures, Leebot- 

 wood, about nine miles from Shrewsbury. 



As a means of giving a definite place in the classification 

 of fossil plants to such fossils as that just described, Schimper 

 has proposed the genus Spiropteris^ in which he places those 

 specimens of ferns that do not afford sufficient characters 

 for the determination of the species to which they belong. 

 For fossils of this nature the genus is very useful, as it gives 

 a fixed, though provisional, position to many interesting 

 specimens which cannot be specifically associated with the 

 fully-developed frond. 



1 Not shown in the figure. 



2 Traite d. Pal^ont. Veget., vol. i.. p. 688, pi. xlix. (1869). 



