380 



Dr. J. J. Bigsby's Brief Account of the [Feb. 21, 



Quebec group and its ill-understood connexion with the immediately con- 

 tiguous strata. 



An intimate acquaintance with this group near Quebec leads me to 

 believe that there, at least, it is a displaced, crumpled, and fractured mass 

 of schist, with thin beds of limestone and calcareous conglomerate inter- 

 leaved, the last crowded with molluscan and crustacean life. 



It is above the Potsdam Sandstone, and on or near the horizon of 

 Calciferous sandstone and the lower layers of Chazy Limestone (Logan 

 and Billings, Report, 1863). Into these (with a distinct tendency still 

 higher) in other parts of North America, the Quebec group probably be- 

 comes fused, and assumes their horizontal position, mineral character, and 

 many of their organic contents. 



The fauna of the Quebec group, consisting of 327 species at Point Levi 

 (Quebec) and in Western Newfoundland, is peculiar, and, of course, is 

 only found there, with the exception of thirteen species found elsewhere in 

 Calciferous sandstone, and eight in Chazy Limestone. They are one-six- 

 teenth of the whole, and are as follows : — 



Calciferous Sandstone : — Lingula Mantelli, L. acuminata, L. Irene, 

 Cameralla calcifera, Helicotoma gorgonia, H. uniangulata, H. perstriata, 

 Fleurotomaria calcifera, P. postumia, Holopma dilucula ?, Ecculiomphalus 

 Canadensis, Murchisonia Anna, Piloceras Canadense (Billings). 



Chazy Limestone : — Ecculiomjphalus Atlanticus, Maclurca Atlantica, 

 Stromatojpora comi^acta (running into B + BL), Climacograptus antenna- 

 rius, Ptilodictya fenestrata ?, Leperditia amygdalina, Camerella varians, 

 Cheirurus iDroliJicus (li\\Ymg%) . ^ 



This group contains, besides the thirteen species just enumerated, 1 74 * 

 allied to those of the Calciferous Sandstone of Central North America, or 

 more or less westward of Montreal. It is this which connects it closely 

 with the sandstone. However, 140 remain typical. 



The fossils of Chazy Limestone met with in the Quebec group only be- 

 long to a few of the basement beds of the former, because these almost 

 immediately, upwards, ^change into a compact mass of crushed Crinoids, 

 Cephalopoda, Gasteropoda, &c. (143 species) — all quite new, and alien 

 from the life below. 



The Calciferous Sandstone, always truly primordial, has in the Canadas 

 and the United States of America 375 species, overspreading vast areas. 

 They may be separated into three sets : — 



1. Thirteen enter the Quebec group. 



2. One hundred and seventy-four are the allies of that group. 



3. One hundred and eighty-eight are foreign to it, and for the most part 

 typical. 



Like its two sister groups, the Calciferous Sandstone is shown, in the 

 middle line of Table D, to display a remarkable tendency to abound in 

 complex and powerful existences, and to paucity in the simple species, in- 



^ These numbers are for the present only approximate, and may be altered. 



