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3. On some New Species of Fossils from the Quebec group. 

 1. SYNCHRONISM OF THE POINT LEVIS LIMESTONES. 



As there has heen a good deal of discussion, with much diversity of 

 opinion, on the subject of the geological age of the rocks at Point LeVis, 

 it may not be out of place, here, to review the evidence upon which the 

 position assigned to them in the recent publications of the Survey, is 

 founded. The question is intimately connected with the characters of the 

 Fauna of the Potsdam group, and I shall therefore, in the first place, give 

 a list of the papers relating thereto, with the species described in each. 



1847. PROF. J. HALL described Scolithus linearis, lAngula prima, 

 and L. antiqua. The first of these was stated to occur in the Potsdam 

 sandstone of the valley of Lake Champlain, " in the partially altered sand- 

 stone of the same age, at the base of the Green Mountains, in Adams, 

 Mass.," in New Jersey, Pennsylvania, Maryland, Virginia, and Tennessee. 

 The two species of Lingula were found in New York. (Pal. N.Y., vol. i.) 



1851. DR. H. A. PROUT described G-raptolithus Hallianus, from the 

 Potsdam sandstone of Wisconsin. (Am. Jour. Sci. (2) xi, p. 187.) This 

 species has been since referred, by Prof. J. Hall, to the genus Dendro- 

 graptus. 



1851. SIR W. E. LOGAN read a paper before the Geological Society 

 of London " On the Occurrence of a Track and Foot-prints of an Animal 

 in the Potsdam sandstone of Lower Canada." He stated that his " atten- 

 tion was first drawn to the track by Mr. Abraham, then editor of the 

 Montreal Gazette, who duly appreciated its possible geological importance, 

 and inserted a notice of it in his daily journal." (Jour. Geo. Soc., vol. 

 vii, p. 247.) 



1852. PROF. R. OWEN described and figured the tracks above men- 

 tioned under the names of Protichnites septem-notatus, P. octo-notatus, 

 P. latuSy P. multinotatus, P. lineatus and P. alternans. As to the 

 affinities of the creature which made the tracks, he says the Limulus 

 " comes nearest to his idea of the kind of animal which has left the im- 

 pressions on the Potsdam sandstone." (Jour. Geo. Soc., vol. viii, p. 214.) 



1852. DR. D. D. OWEN described Orbicula prima, Lingula ampla, 

 L. pinnaformis, Dikelocephalus Minnesotensis, D. Pepinensis, D. Minis- 

 caensis, D. lowensis, D. granulosm, LonchocepJialus Chippewaensis, 

 L. hamulus, CrepicepJialus Wisconsensis, O. Minniscaensis, and Menoce- 

 plialus Minnesotensis, from the Potsdam sandstone of Wisconsin. He also 

 cites with doubt Obolus Apollinis, L. antiqua and L. prima with Orthis 

 and Crinoidal stems from the same beds. (Geol. Rep. on Wisconsin, 

 Iowa and Minnesota.) 



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