396 CAMBRIAN AND SILURIAN IN NOKTH AMERICA. [XV. 



mit of the second fauna. Before we can understand his reasons 

 for maintaining a similar view in 1859, we must notice the 

 history of geological investigation in eastern Canada. So early 

 as 1827, Dr. Bigsby, to whom North American geology owes 

 so much, had given us (Proc. Geol. Soc., I. 37) a careful de- 

 scription of the geology of Quebec and its vicinity. He there 

 found resting directly upon the ancient gneiss a nearly hori- 

 zontal dark-colored conchiferous limestone, having sometimes 

 at its base a calcareous conglomerate, and well displayed on 

 the north shore of the St. Lawrence at Montmorenci and Beau- 

 port. He distinguished, moreover, a third group of rocks, 

 described by him as a "slaty series composed of shale and 

 graywacke, occasionally passing into a brown limestone, and 

 alternating with a calcareous conglomerate in beds, some of 

 them charged with fossils .... derived from the conchifer- 

 ous limestone." (This fossiliferous conglomerate contained 

 also fragments of clay-slate.) From all these circumstances 

 Bigsby concluded that the flat conchiferous limestones were 

 older than the highly inclined graywacke series ; which latter 

 was described as forming the ridge on which Quebec stands, the 

 north shore to Cape Rouge, the island of Orleans, and the 

 southern or Point-Levis shore of the St. Lawrence; where, 

 besides trilobites and the fossils in the conglomerates, he no- 

 ticed what he called vegetable impressions, supposed to be 

 fucoids. These were the graptolites which, nearly thirty years 

 later, were studied, described, and figured for the geological 

 survey of Canada by Professor James Hall, who has shown 

 that two of the species from this locality were described and 

 figured under the name of fucoids by Ad. Brongniart, in 1828. 

 (Geol. Sur. Canada, Decade II. page 60.) Bigsby, in 1827, 

 conceived that the limestones of the north shore might belong 

 to the carboniferous period, and noted the existence of what 

 were called small seams of coal in the graywacke series of the 

 south shore. This substance which I have since describ< -. 1 is, 

 however, entirely distinct from coal, and occurs in fissures, some- 

 times in the interstices of crystalline quartz. It is an insolu- 

 ble hydrocarbonaceous body, brilliant, very fragile, giving a 



