onellus, and Lonchocephalus, in the equivalents of the Potsdam sandstone. The genus Paradoxides however, does not, seem to be represented in this fauna *.
A species of Paradoxides, which appears to be identical with a form occurring in Bohemia and Thuringia, P. spinosus, Boeck, has been met with in altered argillaceous sandstones in a quarry in Quincy, south of Boston, in eastern Massachusetts†.
In Canada, at Point Levis, on the banks of the St. Lawrence, a fauna, possessing a character nearly allied to that mentioned by Dr. D. Owen as occurring in Wisconsin, is seen. Among the thirty-six forms of Crustacea which this fauna affords are two forms of Arionellus, one of Conocephalites, and five of Dikelocephalus. These are associated with fifty-five species of Mollusca, four of Radiata, and forty-two forms of Graptolites, the latter being generically and, in most instances, specifically identical with those of the Skiddaw slates‡.
The fossils of Point Levis occur in limestone conglomerates and in interstratified slates. These rocks appertain to the Quebec group, and represent in this part of North America the calciferous sand-rock §.
In Vermont, as seen at Swanton Falls, the Potsdam sandstones are exhibited in the form of dolomites and red sand-rocks. The lower portion of these afford Conocephalites Adamsi, Bill. ; and from the higher strata C. Teneri, Bill., Paradoxides Thompsons, Hall, P. vermontiana, Hall, and three species of brachiopods are obtained ||.
Strata of the same age, and affording the same forms of Paradoxides, occur on the coast of Labrador, on the north-west side of the Straits of Belle Isle. Here Conocephalites, with two forms of Bathycirus, three of Salteria, and several brachiopods are found associated¶.
The Potsdam sandstones are represented in the north-west portion of Newfoundland. The strata here, which have been termed by the late Mr. Jukes the Lower Slate formation, consist of the Signal-hill sandstones and the St. John's slate (Report on the Geology of Newfoundland).
From the slates on the west side of St. Mary's Bay Mr. C. Bennett obtained Paradoxides Bennetti, Salter, a form before alluded to.
Dr. Dawson refers to the occurrence of a rich primordial fauna in New Brunswick. It affords fourteen species of Conocephalites, two of Paradoxides, one of Microdiscus, and two of Agnostus, associated with six forms of Brachiopoda **.
- Geology of Wisconsin, vol. i. p. 72.
† H. D. Rogers, Geol. of Pennsylvania, vol. ii. pi. 11, p. 816.
‡ Sir W. E. Logan's Report on the Geology of Canada, 1863, p. 232.
§ Professor Dana, in the last edition of the 1 Manual of American Geology ' (1870), p. 171, unites the Potsdam sandstone and the calciferous sand-rock into one group, placing them at the base of the Silurian, and designating the epoch of their deposition as the " Potsdam or primordial period."
|| Report, p. 811.
¶ Report, p. 866.
- Acadian Geology, 2nd edit. p. 641.
