[DAWSON] FOSSIL SPONGER AND OTHER ORGANIC REMAINS 93 



natural facts whicli underlie tlieiii. lo llic publications named in the foot- 

 note to this section.' 



II. — Subdivisions of the (Quebec Group. 



Confining ourselves to the sections on the south shore of the Lower 

 St. Lawrence, the subdivisions, as worked out by Logan and Richardson 

 and more recently by Ells, with the aid of Whiteaves in regard to the 

 Trilobites, Brachiopods, etc., and of Lapworth '•' and Ami in the grapto- 

 litic fauna, ma}' be stated as follows in ascending order : ^ 



1. The Siller y Series, seen at the Chaudière Elver, near Quebec, and 

 also at Matane and Cape Eosier, as well as at Little Métis. Among its 

 characteristic fossils are the little brachiopod Obolella {Linnarssonia) 

 pretiosa, Billings, and Dictyonema sociale of Salter {D. flabellare of Eich- 

 wald), also species of Bryograptus and Clonograptus. The prevalent 

 rocks are grayish sandstones and conglomerates with shales of red, gray 

 and black colours, and more rarely bands of limestone and dolomite. It 

 may be regarded as the base of the Quebec Group proper, and as the 

 equivalent of the Calciferous of more western districtsand of the Tremadoc 

 of Wales, and perhaps as the highest member of the Cambrian system. 



2. The Levis Series ; to Avhich belong the shales, limestones and 

 conglomerates exposed at Levis, opposite the city of Quebec, and which 

 has been recognized as far east as Ste. Anne des Monts. Its most charac- 

 teristic fossils are graptolites of the genera Phyllograptus, Tetragraptus, 

 etc., most of which are described by Hall in his classical monograph on 

 this fauna ; while its Trilobites, etc., have been studied by Billings, and 

 catalogued by Ami, who separates the fossils found in boulders in the 

 conglomerate from those properly belonging to the formation.^ This 

 series is in the horizon of the Upper Calciferous and Chazy, and may be 

 regarded as equivalent to the English Arenig and Skiddaw. 



3. The Marsouin Series ; found at that place and at Griflftn Cove, 

 White Eiver, and eisev.^here, and holding grai^tolites of the genera Diplo- 

 graptus, Cœnograptus, etc. It is apparently of Chazy-Trenton age and 

 equivalent to the English Bala. 



4. Still higher beds holding Diplograptus pristis and other forms 

 characteristic of the Utica shale, and therefore new^er than the Quebec 

 Group proper, occur west of Marsouin Eiver, near Tartigo River and 

 elsewhere. At this period, owing to the subsidence of northern land, the 



1 Appendix to Harrington's Life of Sir William Logan, p. 403 et seq. ; On the 

 Eozoic and Palaeozoic Rocks of Eastern Canada, Journal London Geol. Society, 1888 ; 

 The Quebec Group of Logan, Canadian Record of Science, 1890 ; Salient Points in the 

 Science of the Earth, 1894. 



- Transaction.s Royal Society of Canada, 1886. 



3 For notices of previous work and recent discoveries, see Report by Ells, Geolo- 

 gical Survey of Canada, 1887-S8. 



* Report Geol. Survey of Canada, 1887-88. 



Sec. I v., 1896. 6. 



