371 



Since 1844 Prof. Emmons has continued his observations and 

 discoveries on those bottom rods, and in 1855 he gave a more 

 complete account of Ills Taconic system in the second part of his 

 " American Geology." This book has unfortunately escaped M. 

 Barrande's inquiries, for his attention would be strongly drawn to 

 the new Taconic fossils it contains. It is evident from the new 

 specimen o^ EUptocephahis asajihoides, from the shales of Washing- 

 ton County, New York, figured PI. I, fig. 18, that this trilobite 

 is a Paradoxides related to the group of P. spinosus, perhaps 

 identical with the P. Harlani of Braintree. Besides, the tri- 

 lobite figured PI. I, fig. 16, and called Atops trilineatus, is a true 

 Sao, which genus is among the most characteristic of the Primor- 

 dial fauna of Bohemia and Scandinavia. Prof. Emmons has thus 

 found at least two trilobites of the Primordial fauna in slates form- 

 ing part of his Taconic System. Trilobites are the most impor- 

 tant fossils for the determination of the age of the oldest strata ; 

 the labors of M. M. Barrande and Angelin have shown with what 

 certainty geologists can rely upon them. Other less significant 

 fossils have been found by Emmons, such as Graptolites, Lingulce^ 

 and Oholi, Sections and very detailed descriptions of strata show 

 that the Taconic system, as defined by its discoverer, is composed 

 of shales, slates, limestones, dolomites, conglomerates, sandstones, 

 and iron breccia, whose combined thickness is between 25,000 and 

 30,000 feet, always resting on granite, gneiss, quartzite, and other 

 crystalline rocks ; that it lies at the base of the Silurian (such as 

 the Silurian was first established in England and in America) ; 

 and that this bottom formation extends, according to Emmons 

 himself, from Newfoundland to Maine, Canada, Vermont, Massa- 

 chusetts, Rhode Island, and along the Alleghanies to Georgia. 



A discovery made some time since, but only published last 

 year, has brought before the scientific world new forms of fossils, 

 which, according to M. Barrande, unquestionably belong to the 

 Primordial fauna. The following is the statement of M. Bar- 

 rande, contained in a letter to Prof Bronn of Heidelberg, to be 

 published in the German Geological Journal : " JSfeues Jahrbuchfur 

 Geologie und Petrefahten Kunde^ 



'' Paris, July 16, 1860. 



" I have recently received, thanks to the kindness of M, E. 



Billings, the learned paleontologist of the Geological Survey of Canada, 



