XX11 



>ACTS AND OBSERVATIONS. 



Phillipsburg (Lake Champlain), belong to its base, because its arenaceous beds very soon change 

 upwards into a compact mass of crushed Crinoids, Cephalopoda, &c. (143 species), all quite new, 

 and therefore the product of new conditions. 



Wholly independent of the Quebec group, the Chazy beds spread over vast tracts on the 

 Ottawa, the Upper St. Lawrence, and the Mississippi valleys, and lie conformably upon Calciferous 

 sandstone. It is extremely difficult to separate them. In other words, in America there seems to 

 be no sharp line dividing the Primordial from the beds above it a condition of things, of course, 

 affecting their upper zoological limits. As far as is now known, this line is rarely transgressed in 

 Europe by Silurian life *. 



Many of the Chazy mollusca are really of the Calciferous age, and go no farther than the 

 Chazy, while many which first show in this last bed freely mount up into the higher, strata, 

 Trenton, &c. 



The mineral character of the Chazy beds is unsteady in its best exposures, as seen in the Gulf 

 of St. Lawrence, the Mississippi valley, &c. It may consist of various sandstones, brown shale, 

 and of dolomitic and argillaceous limestone. On the River Ottawa it is a sandstone fifty feet thick, 

 resting, conformably, on a few feet of grey limestone (Calciferous sandstone). 



The presence in some localities of the Chazy layers is indicated by the disappearance of all 

 the Trilobita, except two species of Asaphus. 



Great interest attaches to the Quebec group on account of its zoological contents, its doubtful 

 stratal position, the displacements it has suffered, and the controversies it has occasioned. 



It is clearly on or near the horizon of the Calciferous sandstone, and some of the lower layers 

 of the Chazy rocks. 



The fauna of the Quebec group is very peculiar ; it embraces 332 species at Quebec and in 

 West Newfoundland the life, however, of these two districts being very different specifically, 

 although for 1677 feet (Divisions N, O, P) the same words would describe the strata of both (300 

 miles apart) . 



Its numerous forms of life are almost all of very high organic rank, such as Cephalopoda, 

 Gasteropoda, Trilobita, &c. (see Table N). 



Although there are forty-four Polyzoa well known in the Quebec group (several of them also 

 met with in Australia and England), there are only two Crelenterata upon our present list. All 

 these fossils are in great numbers individually as well as specifically, with the exception just named. 



Our acquaintance with the recurrents of this stage is as yet imperfect. Those which move 

 from bed to bed within the Primordial stage are numerous, and their range is great ; but of those 

 which escape upwards into the Black-River or Trenton group of North-east America, into the stage 

 D of Bohemia, or the Upper Llandeilo of Britain, the number is small, and perhaps doubtful. 



Table O exhibits this flora and fauna under a general aspect, and arranged as they occur in 

 Lower or Upper Primordial. To these are attached corresponding horizons, in whose columns the 

 recurrents are enumerated, their names being placed alongside. They are fourteen in number. Since 

 they are vouched for by the best and most recent authorities, it is not easy to give a reason for 

 their rejection. The transition which is effected at Hof in Bavaria, as recently announced by M. 

 Barrande in a letter to myself, by means of Trilobita and Brachiopoda, is strongly in favour of a 

 far closer connexion between the Primordial and the higher stages than hitherto entertained. ' As 

 recurrence is active within the Primordial mass, it will probably be found, after a time, to exist 

 about its upper limits. We may be on the eve of receiving further evidence, enabling us to 

 estimate more accurately the distinction between Cambrian and Silurian stages. 



These facts are taken from the 'Thesaurus ;' but this very interesting portion of it is the gift 

 of Barrande, Emmons, Hall, Logan, Billings, and is the fruit of their summer toil and winter 

 studies. 



* According to the late determinations of M. Barrande, this transgression takes place, to some extent, at Ilof in 

 Bavaria. 



