236 Proceedings of Learned Societies. 



film on water will displace the camphor-film, and so permanently 

 arrest the motions of the camphor; but a volatile oil will only- 

 arrest the motions while it is present and undergoing evaporation. 

 The motions of camphor on the surface of water are increased 

 by the action of the vapour of benzole and some other volatile sub- 

 stances, such vapours condensing in the liquid form on the camphor, 

 and being then diffused by the adhesion of the water. 



ROYAL SOCIETY, February 20. 



On the Dicyodont Reptilia brought from South Africa, by 

 His Royal Highness Prince Alfred. — A communication was made by 

 Professor R. Owen, describing some fossil remains obtained by His 

 Royal Highness Prince Alfred, during his recent journey in Soutb 

 Africa. They belong to two genera of Dicyodont Reptilia, the 

 first being an unusually perfect specimen of the skull of a species o£ 

 Ptychognathus, which the author proposes to name P. Alfredi. The 

 second specimen is the skull of the largest known species Dicyodon 

 trigric&ps. This skull is remarkable as exemplifying the near equality 

 in size of this extinct two-tusked reptile of South Africa with the 

 existing walrus. The pelvis of the Dicyodon is singularly massive, 

 and offers many points of approach to the mammalian type, which 

 is remarkable when taken into connection with the mammalian 

 tusks in the skull. 



GEOLOGICAL SOCIETY.— February 26. 



On the Ice-worn Rocks of Scotland, by T. F. Jamieson, F.G.S. 

 — The author, first referring to the eroded surface of the rocks be- 

 neath the Drift-bed in Scotland, proceeded to show that the action 

 of ice, and not that of torrents, could produce such markings as he 

 had observed in the bed of a mountain-stream in Argyllshire, down 

 which had poured the torrent caused by the bursting of the reser- 

 voirs of the Crinan Canal. He then advanced reasons for considering 

 that the erosion of the rocks in Scotland was due chiefly to land-ice, 

 and not to water-borne ice, bringing forward remarkable instances 

 of ice-action on the glens and on the hill-sides at Loch Treig and 

 Glen Spean, where moraines, blocs perches, striae, roches mouton- 

 nees, and boulders lifted above the parent-rocks, indicate a northern 

 direction for the great ice-stream from Loch-Treig to the Spean, and 

 then an eastern course on one hand up Loch Laggan, and a western, 

 on the other, down the Spean. Up Glen Roy the ice had apparently 

 passed north-eastwardly, over the watershed, towards the Spey. 

 In Knapdale, Argyllshire, similar evidence is obtained of a great 

 ice-stream passing over hill and dale, here falling into the Sound of 

 Jura. The author referred to Rink's and Sutherland's observations 

 on the continental ice of Greenland, as affording a probable solution 

 of these phenomena; and, objecting to the hypothesis either of 

 floating ice and of debacles being sufficient to account for the con- 



