Ss a 
Bateson eee ee 
of North America with those of E'urope. 361 
Silurian System, (inferior stage.)—This stage is represented 
in the United States by the first six groups of the New York 
series. ‘The Potsdam sandstone with Lingula is probably anal- 
ogous to the sce Ta with Obolus of Russia and the lower 
sandstones of Scandinavia.* These are in the two continents, 
the most ancient fossiliferous rocks, and, when we reflect upon 
their antiquity we are astonished to meet with a genus of shells 
which appears still in the existing creation, which prove that 
the conditions of existence were not very different then from 
those of the present time. 
The siliceous limestones, those of Black River and of Tren- 
ton, are the equivalents of a great part of the inferior Silurian 
stage of Europe, and i occupy the same position as the bitu- 
minous schists and the Orthoceratite limestones of Sweden and 
Russia. The Utica sae and the Hudson River group, with the 
Graptolites at their base, represent the Graptolite slates, which in 
Sweden succeed to the red Orthoceratite limestone. They ar 
also the same as those of Bain in France. 
This succession of deposits in America, contains a large quan- 
tity of fossils,+ among which we have recognized seventeen 
species which in Europe are found in the inferior stage of the 
Silurian system, viz., Calymene Blumenbachii, C. Fischeri, C. 
punctata, Ilenus crassicauda, Lichas laciniata, Ceraurus 
Sarmearn Trinucleus caractact, Phacops Dalmani, Ortho- 
munis or duplex, Lituites convolvans, Bellerophon 
Teishcion, “Spire lynx, Orthis testudinaria, O. Verneuili, Stro- 
matopora entrica, Ptilodictya lanceolata and Chatetes petro~ 
politansie. 0 With the exception of Calymene remKuneNE C. 
punctata, Spirifer lynx, Serer concentrica tilodic- 
tya lanceolata, which rise more or less into the aa beds, the 
species which we have enumerated may be eRe as charac- 
teristic of the lower Silurian stage in both contin 
__ The great ional number of the Trilobites, ‘ives us an 
idea of the considerable development already made by this fami- 
ly, and which corresponds to what is observed in Europe. But 
besides the identities of species, there are still certain analogies 
of genera which we see often manifested in deposits of the same 
epoch. We will cite here, as an example, the genus Jsotelus, 
which in America represents our Asaphus, with eight articula- 
tions, and which like them is proper to the inferior stage of the 
Silurian system 
* According to Professor Sedgwick, the most ancient fossiliferous rocks of 
Wales mon be pot like thos Sar Awerice, characterized by Lingula and Fu- 
beng ae | Geol. Societ 
he first volume of as "paleontology ‘ New York, by Mr. Hall, which is 
ete to , will be entirely devote a description of the fossils of the 
groups w whic i nd . 
will contain more than de plates. The talent and the peooebs courte whe 
the author, gives sufficient assurance of the interest which it will have for science, 
