like Stromatopora, which present, according to Dawson a structure intermediate between the Eozoon of the Laurentian and the genera Parkeria and Loftusia of the Cretaceous and the Eocene. The details are taken from Dr. Dawson's recent presidential address to the Natural History Society of Montreal, in May, 1872, where he has announced some of the results of his studies, yet in progress, on the earlier foraminifera.

In 1856 the late Prof. Emmons described [Amer. Jour. Sci. II, xxii, 389] under the name of Palaeotrochis, certain forms regarded by him as organic, found in North Carolina in a bed of auriferous quartzite, among rocks referred to his Taconic system. Their organic nature has also been maintained by Prof. Wurtz, but from my own examinations, I agree with the opinion expressed by Prof. Hall, and subsequently supported by the observations of Prof. Marsh, [Ibid. II, xxiii, 278; xvl. 217] that the forms to which the name of Palaeotrochis has been given are nothing more than silicious concretions.

As regards the geological horizon of the series of strata to which Sir William Logan has given the name of the Quebec group, the Sillery and Lauzon divisions have as yet yielded to the paleontologist only two species of Obolella and one of Lingula. Our comparisons must therefore be based upon the fauna of the Levis limestones and graptolitic shales, which have already been compared with the Middle Cambrian or Festiniog group of Sedgwick, by the combined labors of Billings and Salter. The former has moreover carefully compared this fauna with that of the lower members of the New York system; in which the succession of organic life appears to have been very much interrupted. Thus, according to Mr. Billings, of the ninety species known to exist in the Chazy limestone of the Ottawa basin, only twenty-two species have been observed to pass up into the directly-overlying Birdseye and Black-River limestones. The break between the Chazy and the underlying Calciferous sandrock, in this region, is still more complete; since, according to the same authority, of forty-four species in the latter only two pass up into the Chazy limestone. This latter break in the succession appears to be filled, in the region to the eastward of the Ottawa basin, by the Levis limestone; which has been studied near Quebec, and also near Phillipsburg, not far from the outlet of Lake Champlain. This formation (including the accompanying graptolitic shales,) has yielded, up to the present

time, 219 species of organic remains, (comprising seventy-four of crustacea, and fifty-one of graptolitidia) none of which, according to Mr. Billings, have been found either in the Potsdam or in the Birdseye and Black River limestone. Twelve of the species of the Levis formation are however met with in the Calciferous, and five in the Chazy of the Ottawa basin, and the Levis is therefore regarded by Mr. Billings as the connecting link between these two formations.

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With regard to the British equivalents of these rocks, the Levis limestone, according to Salter, corresponds to the Tremadoc beds; although the species of Dikellocephalus found in the Levis rocks are by him compared with those found in the Upper Lingula flags or Dolgelly beds. The graptolitic strata of Levis however clearly represent the Lower Llandeilo or Arenig rocks of North Wales, the Skiddaw group of Sedgwick in Cumberland, the graptolitic beds which in Esthonia, according to Schmidt, are found below the orthoceratite-limestones, [Can. Naturalist, I. vi. 345] and those of Victoria in Australia, [Mem. Geol. Sur. III, part 2, 255, 304.] In the Lower Llandeilo and Upper Tremadoc beds there appears to be in North Wales, a mingling of forms of the first and second faunas, as in the Levis and Chazy formations. The latter was already, by Hall, in 1847, declared to be beneath the Silurian horizon then recognized in Great Britain. By its fauna it is comparatively isolated from the strata both below and above it, and stratigraphically as well as paleontologically it would appear to belong rather than to the lower than to the higher rocks. According to a private communication from Prof. James Hall, the Chazy limestone at Middleville, Herkimer county, New York, to the south of the Adirondacks, is wanting, and the basal beds of the Trenton group (the Birdseye limestone) there rest unconformably upon the Calciferous sandrock.

The relations of the various members of the Quebec group to each other, and of the group, as a whole, to the succeeding Trenton and Hudson-River groups, require further elucidation. If, as I am disposed to believe, the southeastward-dipping series of the older strata near Quebec, exhibits the northwest side of an overturned and eroded anticlinal, in which the normal order of the strata is inverted, then the Lauzon and Sillery divisions, which there appear to overlie the Levis limestones and shales, are older rocks, occupying the position of the Potsdam or still

lower members of the Cambrian. Sir William Logan supposes the appearance of these rocks in their present attitude by the side of the strata of the Trenton and Hudson River-groups, in the vicinity of Quebec, to be due to a great dislocation and uplift, subsequent to the deposition of these higher rocks; but, as suggested in my address of last year, I conceive the Quebec group to have been in its present upturned and disturbed condition before the deposition of the Trenton limestones. The supposed dislocation and uplift, extending from the gulf of St. Lawrence to Virginia, is according to this view, but the outcrop of the rocks of the first fauna from beneath the unconformably overlying strata of the second fauna. The later movements along the borders of the Appalachian region have however, to some extent, affected these, in their turn, and thus complicated the relations of the two series. This unconformity, which corresponds to the marked break between the Levis and Trenton faunas, is farther shown by the stratigraphical break and discordance in Herkimer county, New York; and by the fact that beyond the limits of the Ottawa basin, on either side, the limestone of the Trenton group rests directly on the crystalline rocks; the older members of the New York system being altogether absent at the northern outcrop, as well as in the outliers of Trenton limestone seen to the north of Lake Ontario, and as far to the north-east as Lake St. John on the Saguenay. This distribution shows that a considerable movement, just previous to the Trenton period, took place both to the west and the east of the Adirondack region, which formed the southern boundary of the Ottawa basin.

The Levis and Chazy formations, as we have seen, offer a commingling of forms of the first and second faunas, which shows them to belong to a period of transition between the two; but it is remarkable that so far as yet observed, no representatives of the later of these faunas are known to the east and south of the Appalachians, along the Atlantic coast; the first fauna, whether in Massachusetts, New Brunswick or southeastern Newfoundland, being unaccompanied by any forms of the second. The third fauna, on the contrary, is represented in various localities. both within and to the east of the Appalachian region, from Massachusetts to Newfoundland. In parts of Gaspé, and also in Nova Scotia, strata holding forms referred to the Clinton and Niagara divisions are met with, as well as other beds of Lower Helderberg age, associated with species of shells and of plants

which connect this fauna with that of the succeeding Lower Devonian or Erian period. To this Lower Helderberg horizon (corresponding to the Ludlow of England) appear to belong certain fossiliferous beds found along the Atlantic coast of Maine and of New Brunswick, in Nova Scotia and (?) in Newfoundland; as well as others included in the Appalachian belt in Massachusetts, New Hampshire, Vermont and Quebec, along the Connecticut valley and its north-eastern prolongation. The fossiliferous strata just noticed, both in the Connecticut valley, and along the Atlantic coast, occur in small areas among the older crystalline schists, often made up of the ruins of these, and in highly inclined attitudes. The same is true in some places of the similarly situated strata of Cambrian, Devonian and Lower Carboniferous periods. These derived strata, of different ages, have, from their lithological resemblances to the parent rocks, been looked upon as examples of a subsequent alteration of paleozoic sediments; and by a farther extension of this notion, the pre-Cambrian crystalline schists themselves throughout this region have been looked upon as the result of an epigenic change of these various paleozoic strata; portions of which, here and there, were supposed to have escaped conversion, and to have retained more or less perfectly their sedimentary character, and their organic remains, elsewhere obliterated.

From the absence of the second fauna we may conclude that the great Appalachian area was, at least in New England and Canada, above the ocean during its period, and suffered a partial and gradual submergence in the time of the third fauna. This movement corresponds to the well-marked paleontological and stratigraphical break between the second and third faunas in the great continental basin to the westward, made evident by the appearance of the Oneida or Shawangunk conglomerate (apparently derived from the ruins of Lower Cambrian rocks) which, in some parts, overlies the strata of the Hudson-River group, The break is elsewhere shown by the absence of this conglomerate, and of the succeeding formations up to the Lower Helderberg division. This latter, in various localities in the valleys of the Hudson and the St. Lawrence, rests unconformably upon the strata of the second fauna, as it does upon the older crystalline rocks to the eastward.

In Ohio, according to Newberry, the base of the rocks of the third fauna (Clinton and Medina) is represented by a conglo

merate which holds in its pebbles the organic remains of the underlying strata of the second fauna.

To the north-eastward, the island of Anticosti in the gulf of St. Lawrence, presents a succession of about 1400 feet of calcareous strata rich in organic remains, which, according to Mr. Billings, include the species of the Medina, Clinton and Niagara formations, and were named by him, in 1857, the Anticosti group. They rest upon nearly 1000 feet of almost horizontal strata, consisting of limestones and shales rich in organic remains, with many included beds of limestone-conglomerate. This series has by the Geological Survey of Canada been referred to the Hudson-River group, but notwithstanding the large number of forms of the second fauna which it contains, Prof. Shaler is disposed to look upon it as younger, and belonging rather to the succeeding division. There seems not to have been any marked paleontological break between the second and third faunas in this region; and it is worthy of note, in this connection, that in the outlying basin of paleozoic rocks, found at Lake St. John, to the north of Anticosti, Halysites catenulatus is met with in limestones associated with many species of organic remains characteristic of the Trenton and referred to that group. [Geology of Canada, page 165.]

The strata to which, in 1857, Mr. Billings gave the name of the Anticosti group were at the same time designated by him Middle Silurian, in which he subsequently included the local sub-division known as the Guelph formation, which in western Ontario succeeds the Niagara; the name of Upper Silurian being thus reserved for the Lower Helderberg division and the underlying Onondaga formation [Report Geol. Sur. Can. 1857, page 248, and Geol. Can. page 20.] Both the Guelph and the Onondaga have been omitted from the table on page 312; the Guelph because it was not recognized in the New York system, and is by some regarded as but a sub-division of the Niagara; and the Onondaga, for the reason that it is a local deposit of magnesian limestones, wiih gypsums and rock-salt, destitute of organic remains.

As to the name of Middle Silurian, it had some years previously been used by the officers of the government Geological Survey in Great Britain to designate the Lower and Upper Llandovery rocks; but is referred to in 1854 by Sedgwick as one that had, at that time, already been abandoned, (L. E. & D.