No. 4. J HUNT — ON CAMBRIAN AND SILURIAN. 429 



This re-discovery of fossiliferous limestoucs at Point Levis 

 led to farther exploration of the locality, and in 1857, and the 

 following years, a large collection of trilobites, brachiopods, and 

 other organic remains was obtained from these limestones by 

 the Geological Survey of Canada. 



Mr. Billings, who in 1856, had been appointed paleontologist 

 to the Geological Survey, at once commenced the study of these 

 fossils from Point Levis, and at length arrived at the important 

 conclusion that the organic remains there found, belonged not to 

 the summit of the second fauna, but were to be assigned a posi- 

 tion in the first or primordial fauna. This conclusion he com- 

 municated to Mr, Barrande in a letter, dated July 12, 1860, 

 [x\mer. Jour. Sci. II, xxxi, 220] and gave descriptions of many 

 of the organic forms in the Canadian Naturalist for the same 

 year. I have already alluded, in describing the rocks of Point 

 Levis, to the peculiarities of aspect which probably led Dr. 

 Bigsby, in 1827, to confound these fossiliferous limestones, pene- 

 trated by dolomite, with the true dolomitic conglomerates asso- 

 ciated with them, and helped him to suppose the fossils to be 

 derived from the limestones of the north shore, now known to 

 be younger rocks. This mistake was a very natural one at a 

 time when comparative paleontology was unknown. 



Sir William Logan meanwhile made a careful stratigraphical 

 examination of the rocks of Point Levis, and notwithstaudino- 

 the peculiarities of the limestones which there contain the pri- 

 mordial fauna, declared himself, in December, 1860, satisfied 

 that " the fossils are of the age of the strata." In consequence 

 of the discovery of Mr. Billings, Logan now proposed to separate 

 from the Hudson-River group the graywacke series of Bigsby 

 and Bayfield, and ascribed to it a much, greater antiquity ; 

 regarding it as " a great development of strata about the horizon 

 of the Chazy and Calciferous, brought to the surface by an 

 overturn anticlinal fold, with a crack and a great dislocation run- 

 ning along the summit," by which the rocks in question were 

 "brought to overlap the Hudson-River formation." This 

 serfes, to which was assigned a thickness of from 5000 to 7000 

 feet, he named the Quebec group, which included the green 

 sandstones of Sillery, regarded as the summit, the fossiliferous 

 limestones and graptolitic shales at the base, which afterwards 

 received the name of the Levis formation, and a great interme- 

 diate mass of barren shales and sandstones, called the Lauzon 



