STRATIGRAPHIC SEQUENCE 683 



Ordovicic system.* Feet 

 Chazian and Mohawkian series: 



Mingan limestones, etcetera 250 



Covered by the sea — Logan's estimate 1,700 



The long banging Species 



On Anticosti many of the species have a very long time range, often 

 extending through several hundred feet of limestones. This is to be ex- 

 plained not only by the probable rapid deposition of the Cincinnatic and 

 Siluric formations, bnt rather in that the Gulf of Saint Lawrence embay- 

 ment was then on the edge of the continent, on the continental plat- 

 form in close and open connection with the North Atlantic (Poseidon) 

 Ocean; in other words, near the great reservoir of equable environment 

 and longer enduring faunas. The more striking cases are the following- 

 species, with their vertical range given in feet : 



Favosites prolificus gradually changes into F. gothlandicus, and ranges 

 throughout the entire strata of this island, 2,300 feet. All of the tabu- 

 late corals have an extended range, but none are so long enduring as this 

 species. 



Beatricea nodulosa and undulata, 700 feet. 



Hehertella maria, 1,027 feet. 



Dinorthis porcata appears twice, first near the base of A and again nearly 



800 feet higher in Ci-Ce. 

 Orthis laurentina, about 100 feet. 

 Leptcena niiens, 1,060 feet. 

 Stropliomena fluctuosa, 980 feet. 

 Triplecia ortoni, 280 feet. 

 CUtambonites diversus, 720 feet. 

 Parastropliia reversa, 110 feet. 

 StricMandinia lens, 540 feet. 

 Pentamerus ohlongus, 650 feet. 

 Rliyncliotrema anticostiensis, 1,060 feet. 

 Rhynchotrema perlamellosa, 275 feet. 

 RhyncJioneUa (?) janea, 761 feet. 

 Catazyga anticostiensis, 320 feet on south shore and 430 feet on north 



shore. 

 Anoplotheca hemispherica, 650 feet. 

 A try pa marginaUs, 230 feet. 

 Hyattella congesta, over 350 feet. 

 HindeUa urribonata, about 150 feet. 

 Conradella pannosa, 980 feet. 



» Schuchert : Bulletin of the Geological Society of America, vol. 20, 1910, pp. 526-533. 



