No. 4.] HUNT — ON CAMBRIAN AND SILURIAN. 443 



Philos. Mag. Ill, viii, 303, 367, 501,) and is also rejected by 

 Lyell, (Student's Manual of Geology, page 452.) It is not used 

 by Murehison, cither in his Silurian System or in the various 

 editions of SiJuri^i, or by Ramsay, who however speaks of the 

 Llandovery rocks as an intermediate series, (Mem. Geol. Survey 

 III, part 2, page 2.) Inasmuch as the name of Silurian was 

 erroneously applied to the rocks of the second fauna, and pro- 

 perly belongs to those of the third fuma only, that of Middle 

 Silurian should b crejected from our nomenclature in North 

 America, as has already been done in England. The strata to 

 which it has been applied, on both sides of the Atlantic, are how- 

 ever important as illustrations of the passage from one fauna to 

 another. 



The history of the introduction of the names of Silurian and 

 Devonian into North American geology demands our notice. 

 Prof. Hall, as we have seen, while recognizins: in the rocks of 

 the New York system the representatives alike of the British 

 Cambrian, Silurian and Devonian, wisely refrained from adopt- 

 ing this nomenclature, drawn from a reirion where wide diversities 

 of opinion and controversies existed as to the value and signifi- 

 cance of these divisions. Lyell however in the account of his 

 first journey to the United States, published in 1845, applied 

 the terms Lower and Upper Silurian and Devonian to our paleozoic 

 rocks. Later, in 1846, de Verneuil, the friend and the colleague of 

 Murehison in his Russian researches, visited the United States, 

 and on his return to France published, in 1847, (Bui. Soc. Geol. 

 de Fr. II, iv, 12, 646) an elaborate comparison between the 

 European paleozoic deposits and those of North America, as 

 made known by Hall and others. He proposed to group the 

 whole of the rocks of the New York system, up to the summit of 

 the Hudson-River group, in the Lower Silurian, and the suc- 

 ceedmg members, including the Lower Helderberg, and the 

 overlying Oriskany, in the Upper Silurian ; the remaining form- 

 ations to the base of the Carboniferous system being called 

 Devonian. This essay by de Verneuil was translated and 

 abridged by Prof. Hall, and published by him in the American 

 Journal of Science (II. v. 176, 359; vii. 45, 218,) with critical 

 remarks, wherein he objected to the application of this disputed 

 nomenclature to North American geology. 



Meanwhile the Geological Survey of Canada was in progress 

 under Logan, who in his preliminary report in 1842, and in his 



