628 HISTOEICAL GEOLOGY. 



Address of H. S. "Williams, Am. Assoc, 1892.) The Ida shales of Bolivia are Corniferous, 

 and the Huamampampa sandstone is Hamilton. 



In southwestern China Richthofen obtained from the Devonian beds the wide-range 

 fossils Pentamerus galeatus, Atrypa reticularis var. desquamata, Merista plebeia, Spirifer 

 Verneuili { = disju7ictiis), Orthis striatula, Productus subaciileatiis, Strophalosia pro- 

 ductoides, EhynchoneUa cuboides, B.pxignus, Aiilopora tubiformis (China, iv., 75). 



Australian Devonian beds of the Hydal District, and to the north and south of it, have 

 afforded the species Cyathophyllum Damnoniense, Favosites reticulatus, F. fibrosus, 

 Heliolites porosus, Chonetes Hardrensis, Orthis striatula, Bhynchonella pleurodon, B. 

 pugnus, B. cuboides, Atrypa reticularis, Spirifer Verneuili, and also the plant Lepido- 

 dendron (W. B. Clarke, On. Sedim. Form. N.S.W., 4th edit., 1882). The Devonian 

 occurs also in Queensland, and near Bathurst in Tasmania. 



GEOLOGICAL AND GEOGRAPHICAL PROGRESS DURING THE DEVONIAN. 



AMERICAN. 



In' the Devonian era, as in the U]Dper Silurian, the great rock formations 

 that are open to investigation were the work of the Interior Continental 

 waters. Progress was still, in the main, endogenous, or within the Interior 

 Sea. Xo Paleozoic rocks, later than the Lower Silurian, have yet been re- 

 ported from the Atlantic border, along the coast region of New Jersey and 

 the states southward. 



The coniined condition of the Eastern Interior Sea, or Bay, had, with the 

 progress of the era, an increasingly profound influence on the nature of the 

 successive formations. The bay had its northwest passage over Michigan open, 

 but not the northeast passage to Canada. The Devonian, as has been shown, 

 began, like the Silurian, with beach and sea-border deposition, sparingly 

 fossiliferous, marking off the coast-line on the north and northeast, and an 

 off-shore bay-like formation — the Schoharie — bearing evidence of abundant 

 life. But these rocks had acquired little thickness before the commencement 

 of the Corniferous limestone formation, or rock coral-reef, when clearer 

 waters, with growing Corals, Crinoids, Trilobites, and other species of the 

 purer seas, were in great profusion, and spread from near the Hudson to 

 Missouri and Iowa. The waters reached north to Mackinac, the head of a 

 great Michigan bay of the era, but appear not to have covered northern 

 Illinois or Wisconsin. Moreover, the Canada and New England seas also 

 had their coral reefs. 



It is remarkable that this coral-reef rock is not recognized over Pennsyl- 

 vania and to the southwest. The Eastern Interior Sea had open connection 

 with the Central Interior by the northwest. As to the southern entrance, 

 nothing is known. 



At the close of the Early Devonian the evidences of clear seas — the 

 Corals and Crinoids, with most of the attendant life — disappear, migrating no 

 one knows whither. Depositions of silt, mud, and sand prevail to the east- 

 ward with various alternations and but thin intercalations of limestone ; and 

 so it was also over the Central Interior, except sparingly in the Hamilton 



