448 THE CANADIAN NATURALIST. [Vol. vl. 



and much improved edition of this excellent Manual (1872), 

 Prof. Giekie, the director of the Geological Survey of Scotland? 

 has substituted the nomenclature of Murchison ; with the impor- 

 tant exception, however, that he follows Hicks and Salter in 

 separating the Menevian from the Lingula-flags, and uniting it 

 with the underlying Harlech rocks (as has been done in the table 

 on page 312), giving to the two the name of Cambrian [loc. cit., 

 pages 526-529], and thus, on good paleontological grounds, ex- 

 tending this name above the horizon admitted by Murchison. 

 Barrande, on the contrary, in his recent essay on trilobites (1871, 

 page 250), makes the Silurian to include not only the Lingula- 

 flags proper (Maentwrog and Dolgelly), but the Menevian, and 

 even a great part of the Harlech rocks themselves (the Cambrian 

 of Murchison and the Geological Survey), for the reason that the 

 primordial fauna has now been shown by Hicks to extend towards 

 their base. This, although consistent with Barrande's previous 

 views as to the extension of the name Silurian, is a still greater 

 violation of historic truth. By thus making the Silurian system 

 of Murchison to include successively the Upper Cambrian and 

 the Middle Cambrian of Sedgwick, and finally his Lower Cam- 

 brian, (the Cambrian system of Murchison himself,) we seem to 

 have arrived at a rediictlo ad ahsurdum of the Silurian nomen- 

 clature ; and we may apply to Siluria, as Sedgwick has already 

 done, the apt quotation once used by Conybeare, with reference 

 to the Graywacke of the older geologists, which it replaces ; '' est 

 Jupiter quodcunque vides.'^ 



It would be unjust to conclude this historical sketch of the 

 names Cambrian and Silurian in Geology, without a passing 

 tribute to the venerable Sedgwick, who to-day, at the age of 

 eighty-seven years, still retains unimpaired his great powers of 

 mind, and his interest in the progress of geological science. The 

 labors of his successors in the study of British geology, up to the 

 present time, have only served to confirm the exactitude of his 

 early stratigraphical determinations ; and the last results of in- 

 vestigations on both continents unite in showing that in the 

 Cambrian series, as defined by him more than a generation since, 

 he laid, on a sure foundation, the bases of paleozoic geology. 



