394 PROCEEDINGS OP THE GEOLOGICAL SOCIETT. [May 10, 



onellus, and LoncliocepTiahis, in the equivalents of the Potsdam sand- 

 stone. The genus Paradoxides however, does not, seem to he 

 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 Quiney, 

 south of Boston, in eastern Massachusetts f. 



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 Ario- 

 nellus, one of Conocephalites, and five of Dikehcejphalus. These are 

 associated with fifty-five species of MoUusca, 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 J. 



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 Yermont, as seen at Swanton Falls, the Potsdam sandstones are 

 exhibited in the form of dolomites and red sand-rocks. The lower 

 portion of these afibrd Conoceplialites Adamsi, BUI. ; and from the 

 higher strata G. Teneri, Bill., Paradoxides Thompsoni, Hall, P. ver- 

 montiana, 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-Avest side of the 

 Straits of Belle Isle. Here Conocephalites, with two forms of Ba- 

 thycirus, three of Salteria, and several brachiopods are found asso- 

 ciated ^. 



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 New- 

 foundland). 



From the slates on the west side of St. Mary's Bay Mr. C. 

 Bennett obtained Paradoxides Bennetti, Salter, a form before al- 

 luded 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. 



f H. D. Rogers, Geol. of Pennsylvania, vol. ii. pi. 11, p. 816. 



i Sir W. E. Logan's Eeport on the Geology of Canada, 1863, p. 232. 



§ Professor Dana, in the last edition of the ' 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." 



II Eeport, p. 811. % Eeport, p. 866. 



** Acadian Geology, 2ud edit. p. 641. 



