Affinities of Fossil Plants from tine Palaeozoic Bocks. 249 



III. " On the Nature of Electro-capillary Phenomena. I. Their Rela- 

 tion to the Potential Differences between Solutions." By 

 S. W. J. SMITH. Communicated by Professor RUCKER, 

 Sec.R.S. 



" On the Structure and Affinities of Fossil Plants from the 

 Palaeozoic Eocks. III. On Medullosa anglica, a new Repre- 

 sentative of the Cycadofilices." By D. H. SCOTT, M.A., Ph.D., 

 F.R.S., Hon. Keeper of the Jodrell Laboratory, Royal Gardens. 

 Kew. Received December 21, 1898 Read January 26, 1899. 



(Abstract.) 



The existence of a group of fossil plants, combining in their orga- 

 nisation certain characters of the Ferns and the Cycads, has been 

 recognised, of late years, by several palseobotanists, as, for example, by 

 the late Professor W. C. Williamson, Count Solms-Laubach, Mr. 

 Seward, and the author. The convenient name, Cycadofilices, has 

 recently been proposed by Professor Potonie to designate the group in 

 question, which now includes several, somewhat heterogeneous, genera, 

 among which Lyginodendron, Heterangium, and Medullosa may be men- 

 tioned. 



Several species of the genus Medullosa (founded in 1832 by Cotta) 

 have already been described, from the Permian and Upper Coal- 

 measures of the Continent. They agree in the extraordinarily complex 

 structure of the stem, which, as shown by Zeiller and Solms-Laubach, 

 resembles in the ground plan of its organisation, that of a highly 

 differentiated Fern, of the usual polystelic type, but with the addition 

 of a zone of secondary wood and bast, sometimes reaching an immense 

 thickness, developed around each stele. The mature stem thus acquired 

 a Cycad-like character. The structure, however, has been extremely 

 difficult to interpret owing to the comparative rarity and incomplete 

 character of the specimens hitherto known. 



No stem of a Medullosa has hitherto been recorded from this 

 country, though specimens of Myeloxylon, now known to have been 

 the petioles of Medullosa, are frequent in the calcareous nodules of the 

 Lower Coal-measures. 



The author has recently had the opportunity of investigating several 

 excellent specimens of a new species of Medullosa from the Ganister 

 Beds of Lancashire. These fossils are of special interest on several 

 grounds ; they are considerably more ancient than any members of 

 the genus previously described, they are the first English specimens 

 recorded, they are preserved in a more complete and perfect form than 



