428 THE CANADIxlN NATURALIST. [VoL vi. 



rocks in Canada, it is to be said that the graptolites first noticed 

 by Bigsby in 1827, were re-discovered by the Geological Survey, 

 at Point Levis in 1854, and having been placed in the hands of 

 Prof. James Hall, (who in that year first saw the rocks in ques- 

 tion) were partially described by him in a communication to Sir 

 W. E. Logan, dated April, 1855, and subsequently at length in 

 1858 [Report Geol. Survey for 1857, page 109, and Decade II.] 

 They were new forms, it is true, but the horizon of the grap- 

 tolites, both in New York and in Sweden, was the same as that 

 already assigned by Logan to the Poiut-Levis rocks. Thus 

 these fossils appeared to sustain his view, and they were accord- 

 ingly described as belonging to the Hudson-River group. 



Up to 1856, no other organic remains than the graptolites and 

 the two species of brachiopods noticed by Sir William Logan, 

 were known to the Geological Survey as belonging to the Point 

 Levis rocks; the trilobites long before observed by Bigsby not 

 having been re-discovered. In 1856, the present writer, while 

 engaged in a lithological study of the various rocks of Point 

 Levis, found in the vicinity of the graptolitic shales, beds of 

 what were described by him in 1857, [Report Geol. Surv. 1853- 

 56, page 465,] as " fine granular opaque lim*estones, weathering 

 bluish-gray, and holding in abundance remains of orthoceratites, 

 trilobites, and other fossils; which are replaced by a yellow- 

 weathering dolomite." In these, which are probably what 

 Bigsby had long before described as fossiliferous conglomerates, 

 the dolomitic matter is so arranged as to suggest a resemblance 

 to certain beds which are really conglomerate in character, and 

 were, at the same time, described by me as interstratified with 

 the fossiliferous limestones, and as holding pebbles of pure 

 limestone, of dolomite, and occasionally of quartz and of argillite ;• 

 the whole cemented by a yellow-weathering dolomite, and occa- 

 sionally by a nearly pure carbonate of lime. [Ibid 466.] The 

 included fragments of argillite, (previously noticed by Bigsby) 

 which are greenish or purplish in color, with lustrous surfaces, 

 are precisely similar to those which form great beds in the crys- 

 talline schists of the Green Mountain series of the Appalachian 

 hills, which extend in a north-east and south-west course along 

 the south-eastern border of the rocks of the Quebec group. I 

 conceive that these argillite fragments, (like those in the Potsdam 

 conglomerate near Lake Champlain, referred to in my address 

 of last year,) are derived from the ancient schists of the Appal- 

 lachians. 



