ex GENERAL SUMMARY OF SCIENTIFIC AND 



of Suess, the mica-schists and the granites of Casauna and 

 the Gailthal have been described as Carboniferous, and sup- 

 posed to be even more recent than certain strata undoubt- 

 edly of this age. Stache has shown that, besides the Car- 

 boniferous beds, important masses of fossiliferous Silurian 

 and Cambrian strata are present, and that the crystalline 

 schists of the region really occupy a position unconformably 

 beneath the old paleozoic strata. 



The evidence accumulates that the whole Cambrian series 

 in Wales, as originally defined by Sedgwick [Record, 1872, 

 p. xxxvi.], extending upward to the unconformably overlying 

 May Hill sandstone (the equivalent of the Oneida of the 

 New York system), is a single physical series. The strati- 

 graphical breaks supposed by Ramsay to exist in Wales 

 above and below the Tremadoc rocks are not recognized by 

 Hicks in his recent study of the ancient rocks at St. David's. 

 The two most important paleontological breaks are at the 

 top of the Menevian and of the Tremadoc. The Silurian 

 and Cambrian nomenclature is asjain much discussed in En- 

 gland, and the fact that the Silurian of Murchison has not 

 and never has had any base-line is insisted upon. Some, 

 with Hughes, follow Sedgwick in confining the Silurian to 

 the strata above the May Hill sandstone, and give to the 

 rocks from this horizon to the top of the Tremadoc the 

 name of Upper Cambrian, originally applied by Sedgwick ; 

 while a greater number restrict the name of Cambrian to 

 the strata below the last-named horizon, and give the name 

 of Cambro-Silurian, or that of Lower Silurian, to the Upper 

 Cambrian. Dewalque has investigated the ancient rocks of 

 the Ardennes, in Belgium, and shown that the whole series 

 of the Cambrian from the Harlech to the Tremadoc inclu- 

 sive, is probably represented in that region. 



The researches of J. Arthur Phillips on the metalliferous 

 rocks of Cornwall cover a great variety of important points. 

 He shows, from a large number of chemical analyses and 

 microscopic studies, that the so-called killas are more or less 

 crystalline schists, often containing crystallized magnetite, 

 quartz, chlorite, and hornblende; and points out that, though 

 of very \arying composition, they all differ so widely from 

 granite that no reconstruction or alteration of them could 

 ever convert them into this rock, as speculators in geol- 



