PRESIDENTIAL ADDRESS, 455 
Walcott in his series of papers published in the Smithsonian Miscellaneous 
Collections, 
In the New Brunswick portion of the eastern or Atlantic life-province the 
strata yielding Paradowides follow those bearing the Protolenus fauna. Six 
species of Paradoxides have been obtained from this horizon, including 
P. davidis, together with the following genera: Agnostus, Agranlos, Liostracus, 
Conocoryphe, and Ctenicephalus. Schuchert points out that this fauna is 
‘closely allied to the Paradoxides faunas of Wales and Sweden, but less so with 
that of Bohemia.’’ 
In Southern Newfoundland Walcott showed that the base of the Middle 
Cambrian division is marked in Manuel’s Brook by a conglomerate containing 
fossils of the lower or Georgian terrane, thus indicating elevation and erosion of 
the Lower Cambrian rocks. Higher up the strata yielded Paradoxides davidis 
and P. bennetti. 
Important evidence pointing to the conclusion that the Paradoxides fauna of 
the eastern or Atlantic province encroached to some extent on the eastern part of 
the western life-province has been obtained by Walcott at St. Albans, Vermont. 
But the suggestion has been made by Schuchert that their present position is 
there due to north-westerly thrusting.® 
It should be borne in mind that in Middle Cambrian time the eastern and 
western parts of the western life-province were evidently separated from each 
other by a land barrier, owing to crustal movement, which was probably con- 
nected with the elevation of the Lower Cambrian rocks in the region where they 
were subjected to erosion. 
In the upper division of the Cambrian system in North America there is a 
marked change in the fauna. Its characteristic features are thus clearly sum- 
marised by Schuchert : ‘In a general way it may be said that the Ozarkic period 
of Ulrich (Upper Cambrian) begins with the trilobite genus Dikelocephalus 
and the nrst distinct molluscan fauna. . . . The trilobites and inarticulate 
brachiopods (greatly reduced in species) are still Cambrian in aspect, while the 
new faunal feature consists in a rapid evolution, in form and size, of the coiled 
gasteropods, and of both straight and coiled cephalopods. The latter are dis- 
tinguished from those of subsequent periods by the exceedingly close arrange- 
ment of the septa.’® 
The distinctive trilobite genus of the Upper Cambrian strata of the western 
life-province is Dikelocephalus, where it is associated with an American facies 
of fossils. The eastern or Atlantic province is characterised by Olenids, 
though Dikelocephalus also occurs, and by typical European forms. In Minne- 
sota and Wisconsin, where the strata consist of sandstones, dolomites, and 
shales, two species of Dikelocephalus have been obtained, together with other 
genera of trilobites such as Agnostus and Illenurus; the limuloid Aglaspis; and 
the gasteropods Holopea, Ophileta, and Raphistoma. 
In certain areas this period is characterised by a great succession of cal- 
careous deposits, comprising parts of the Shenandoah limestone and Kittatinny 
dolomite in New Jersey, portions of the Knox dolomite in Tennessee, and of the 
dolomite and limestone in Oklahoma. In some of these localities, at least, the 
lower portions of this calcareous series are grouped with the Upper Cambrian 
sediments, while the upper parts are classed with Lower Silurian or Ordovician 
strata. The researches of American paleontologists have shown that in certain 
areas there is a mixed Cambrian and Ordovician fauna in some of the beds, as in 
the Tremadoc rocks of Wales. This commingling of faunas is exemplified in the 
case of the Beekmantown limestone, which is grouped with the Ordovician 
(Lower Silurian) rocks by most American geologists. Ulrich and Schuchert, on 
the other hand, regard it as a formation (the Canadic) distinct from the over- 
lying Ordovician system. 
The type areas of the Beekmantown limestone are Lake Champlain, the 
Mingan Islands, and Newfoundland, where the strata consist mainly of a 
succession of limestones and dolomites over 1,000 feet thick. The fossils are 
chiefly molluscan, comprising lamellibranchs, gasteropods, and cephalopods. 
The lamellibranchs are represented, among others, by the genera Huchasma 
* Bull. Geol. Soc. of Amer., vol. xx. (1910), p. 522. ® [bid. 
° Op. cit., p. 524. 
