682 JAMES PERRIN SMITH 



of the Tully limestone there was ushered in a fauna that could 

 not possibly have been developed out of its local predecessors 

 in the Hamilton beds, but whose affinities are with the Upper 

 Devonian of Europe and Asia ; in this latter region the Cuboides 

 fauna is genetically connected with its predecessors of the Lower 

 and Middle Devonian. In this invasion of the American water.s 

 by the Cuboides fauna, we have an undoubted zone, the first great 

 interregional migration that can be traced in the history of the 

 earth. But, as has been shown by Professor Williams, 1 this 

 means something more than a mere migration, it means a com- 

 plete readjustment of the faunal geography of the time. The 

 invasion thus begun was kept up during the succeeding Intumes- 

 cens zone, when Eurasian cephalopods began to make their way 

 from the northwest into the New York 2 province. In these two 

 zones we have divisions that are stratigraphically as well as 

 faunally homotaxial with European beds, that is, they are 

 virtually contemporaneous with them. 



The Lower Carboniferous is well known to have beeen a time 

 of extensive encroachment of the sea on the land, in Europe 

 and America, but the boundaries of the sea were not uniform 

 during the various stages of this age. 3 Oscillations within the 

 regions were common, and sometimes they were great enough to 

 allow the influx of an exotic fauna, such as those of the Kinder- 

 hook horizon, and of the St. Louis division. On a smaller scale 

 the inter-provincial migrations, or colonies, are known at several 

 different horizons of the Lower Carboniferous, occurring always 

 at a time of expansion of the sea, as in the Burlington division 

 of the Osage, and the St. Louis beds. 4 



The Upper Carboniferous, on the other hand, in the Missis- 

 sippi valley region of the United States, and in western Europe 



'The Cuboides Zone and its Fauna, Bull. Geol. Soc. Amer. Vol. 1, 1890. 



2 J. M. Clarke : Naples Fauna, Sixteenth Ann. Rep. New York State Geol., 1898. 



3S.Weller: Jour. Geol., Vol. VI, 1898, Classification of the Mississippian 

 Series. 



4 H. S. Williams: Amer. Jour. Sci., Vol. XLIV, 1895, On the Recurrence of 

 Devonian Fossils in Strata of Carboniferous age. 



