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GENERAL OUTLINE OF THE GEOLOGY. 13 
the southward, he has deduced the direction of the outcrop of the forma- 
tion, where, from the thick covering of drift and alluvium, no natural 
exposures exist. While this method of tracing the limit of the Devonian 
beds, probably affords as near an approximation to the fact as can at pre- 
sent be made, it must be remembered that where so great a thickness of 
unconsolidated drift and alluvium intervenes, and where formations even 
of Cretaceous age may overlap these older rocks, saline waters, even 
though emanating strictly from a single series of beds, may travel far in 
the porous layers of the superficial formations before reaching the surface. 
25. The Devonian rocks already mentioned as occurring on the head 
waters of the Mackenzie near Methy Portage appear, from Sir J. Richard- 
son’s observations, to occupy a wide belt of country from that place to 
the Arctic Sea. Their eastern edges rest against the border of the 
Laurentian region, and the underlying Silurian appears only in iso- 
lated localities. The rocks consist of limestones and shales highly charged 
with bituminous matter. He obtained from them specimens of Productu, 
Spirifer, Orthis resembling O. resupinata, Terebratula reticularis, and a 
Pleurotomaria which Mr. Woodward considered Devonian.* Also a 
Pteropod “apparently Tentaculites fissurella of Hall, a Chonetes, the 
Strophomena setigera of Hall, and Avicula levis of the same author,” a 
Strombodes (Cystiphyllum?) and Favosites, like F. polymorpha. Prof. 
Meek, who has had the advantage of studying a collection of fossils from 
the Valley of the Mackenzie, made by Major R. Kennicott and some of 
the Hudson’s Bay Company’s servants, has described and figured a 
number of species, some of them for the first time, in a paper con- 
tributed to the Chicago Academy of Sciences. — He refers the 
beds from which they were obtained, and which are the same as those 
already described by Sir J. Richardson, and are very extensively 
developed, to the horizon of the Hamilton rocks and Genesee Slates. 
Prof. Meek gives the following list of forms from this very interesting 
area of the Devonian :— 
Cyathophyllum arcticum, Meek; Cystiphyllum Americanum var 
arcticum, Meek; Aulophyllum? fRichardsoni, Meek; Zaphrentis recta, 
Meek; Zaphrentis Macfarlanei, Meek; Smithia Verrilli, Meek; Combo- 
phylum multiradiatum, Meek; Palwocyclus Kirbyi, Meek; Favosites 
polymorpha, Goldfuss ; Alveolites vallorum, Meek ; Lingula minuta, Meek ; 
Strophomena demissa, Conrad; Strophomena (Strophodonta) sub-demissa, 

* Journal of a Boat Voyage through Rupert’s Land, vol. I, p. 122. 
t Trans. Chicago Acad. Sci., vol. I. 

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