BRITISH ASSOCIATION MEETING. 



431 



rocks of North America, have as yet afforded no trace whatever of former life. 

 And yet, such Cambrian rocks are in parts of the Longmynd, and specially in 

 the lofty mountains of the North Western Highlands, much less metamorphosed 

 than many of the crystalline rocks which lie upon them. Rising in the scale of 

 successive deposits, we find a corresponding rise in the signs of former life on 

 reaching that stage in the earlier slaty and schistose rocks in which animal 

 remains begin clearly to show themselves. Thus, the Primordial Zone of M. 

 Barrande is, according to that eminent man, the oldest fauna of his Silurian 

 Basin in Bohemia.* 



In the classification adopted by Sir Henry De la Beche and his associates, 

 the Lingula Flags (the equivalent of the Zone Primordiale of Barrande) are 

 similarly placed at the base of the Silurian System. This Primordial Zone is 

 also classed as the Lowest Silurian by De Yerneuil, in Spain ; by James Hall, 

 Dale Owen and others, in the United States ; and by Sir W. Logan, Sterry 

 Hunt, and Billings, in Canada.f 



In the last year, M. Barrande has most ably compared the North American 

 Taconic group of Emmons $ with his own primordial Silurian fauna of Bohemia, 

 and other parts of Europe ; and although that sound paleontologist, Mr. J ames 

 Hall, has not hitherto quite coincided with M. Barrande in some details, § it is 

 evident that the primordial fauna occurs in many parts of North America. 

 And as the true order of succession has been ascertained, we now know that 

 the Taconic group is of the same age as the lower "Wisconsin beds described 

 by Dale Owen, with their Paradoxides, Dikelocephalus, &c, as well as of the 

 lower portion of the Quebec rocks, with their Conocephalus, Axionellus, &c, 

 described by Logan and Billings. Of the crystalline sc) lists of Massachusetts, 

 containing the noble specimen of Paradoxides described by W. Rogers, and of 

 the Vermont beds, with their Oleni, it follows that the Primordial Silurian 

 Zone of Barrande (the lower Lingula-flags of Britain) is largely represented in 

 North America, however it may occupy an inverted position in some cases, and 

 in others be altered into crystalline rocks. 



In determining this question due regard has been had to the great convul- 

 sions, inversions, and breaks, to which these ancient rocks of North America 

 have been subjected, as described by Professors Henry and W. Rogers. 



* I learn, however, that in Bohemia, Dr. Fritsch has recently discovered strata 

 lying beneath the mass of the Primordial Zone of Barrande, and in rocks hitherto 

 considered azoic the burrows of annelide animals similar to those of our own 

 Longmynd. 



t In completing at his own cost a geological survey of Spain, in which he has 

 been occupied for several years, and in the carrying out of which he has determined 

 the width of the sedimentary rocks of the Peninsula (including the Primordial 

 Silurian Zone, discovered by that zealous explorer, M. Casiano de Prado), M. de 

 Verneuil has in the last few months chiefly examined the eastern part of the king- 

 dom where few of the older palaeozoic rocks exist. I am, however, informed by 

 him, that Upper Silurian rocks with Cardiola interrupta, identical with those of 

 France and Bohemia, occur along the southern flanks of the Pyrenees, and also 

 re-occur in the Sierra Morena, in strata that over-lie the great mass of Lower 

 Silurian rocks as formerly described by M. Casiano de Prado and himself. The 

 southern face of the Pyrenees, he further informs me, is specially marked by the 

 display of mural masses of Carboniferous strata, which, succeeding the Devonian 

 rocks, are not arranged in basin shape, but stand out in vertical or highly inclined 

 positions, and are followed by extensive conglomerates and marls of Triassic age, 

 and these by deposits charged with fossils of the Lias. 



J The Silurian classification was proposed by me in 1835, and in the following 

 year, 1836, Dr. Emmons suggested that his black shale rocks, which he called 

 Taconic, were older than any I described. 



§ Nor are the writings of the Professors W. B. and H. D. Rogers in unison with 

 the opinions of the authors here cited. 



