Trof. H. A: Nicholson — On Hemiphyllutn siluriense, Tomes. 173 



authority, re^^ards the production of hummocks and their glaciation 

 up to a height of 600 feet upon the coast of Norway as the result of 

 floating-ice.^ 



20. The absence of transported boulders and striations upon the 

 surface of many parts of the high plateaux of Norway is doubtless, 

 in part, attributable to the capacity of ice to flow over loose obstacles, 

 and the frequent want of higher ridges to furnish material by their 

 debris falling upon the ice, which might afterwards work through 

 the mass. 



21. The faith in glaciers as great erosive agents has been so 

 severely shaken, that most geologists who personally study those 

 still existing do not attribute to them much greater power than that 

 of removing soft materials, or are even sceptical of this power — ■ 

 as, for instance, Prof. Penck of the University of Vienna, who has 

 been misquoted as having proved their great potency.^ To this 

 scepticism, it seems to me that these notes must contribute, especially 

 when applied to the hypothetical excavation or modification of great 

 lake-basins, and the transportation of northern materials in the 

 Boulder-clay over the broad plains of America, as there were no 

 mountains of adequate height with peaks and screes to supply the 

 detritus sufficient to furnish the surface of the glaciers with all the 

 boreal material of the drift, which now covers half a continent. 



University of Missouri, Feb. 1887. 



YII. — On Hemiphtllum sjluriense, Tomes. 



By H". Alleyne Nicholson, M.D., D.Sc, 

 Eegius Professor of Natural History in the University of Aberdeen. 



IN the last Number of the Geological Magazine there is published 

 a paper by Mr. Eobert F. Tomes dealing with two Corals from 

 the Silurian rocks of Britain. For the reception of one of these 

 Corals Mr. Tomes proposes to form a new genus under the name of 

 Hemiphyllum. The single species of this proposed genus he identifies, 

 somewhat doubtfully, with the form described by M'Coy (Ann. Nat. 

 Hist. ser. 2, vol. vi. p. 281, 1850) under the title of Cyathaxonia 

 siluriensis ; and he therefore describes it as Memipliyllum siluriense, 

 M'Coy, sp., with a note of interrogation. 



I wish, however, to point out, in the first place, that the description 

 and figures given by Mr. Tomes of this Coral render it perfectly 

 certain that he has had to deal with a species of the genus CalostyJis, 

 Lindstr., founded long ago, and rightly referred to a position among 

 the EujpsammidcB, by Dr. Gustav Lindstrom (Ofversigt af Kongl. 

 Vetenskaps-Akad. Forhandl. 1868, and Kongl. Svenska Vetenskaps- 

 Akad. Handl. Bd. ix. 1870). The proposed genus Hemiphyllum, 

 Tomes, cannot, therefore, be sustained, and the name must simply 



^ Discourse before Meeting of Scandinavian Naturalists, Copenhagen, 1873. 

 "^ Geological Magazine, April, 1883. 



