189f..] -"^1 [Smith. 



Tnterch<uige of Life Between East and West. 



The many beds of marine fossils in the Productive Coal Measures are 

 simply transgressions from the western sea, and reach no further east 

 than Pennsj'lvania and West Virginia. The Appalachian system was 

 the western border of the ancient Atlantis* which separated the Euro- 

 pean from the Pacific waters, while the great Indo-Australianf conti- 

 nent bounded the Pacific ocean on the south. This ocean must have 

 stretched from the American Coal Measures to Eastern China, the Bait 

 range in India, the Ural mountains on the borders of Russia, and into 

 the Arctic regions, for we find related faunas in all these places. "What- 

 ever we have of western European Coal Measure species must have 

 migrated from this direction, since on tlie east there was no direct com- 

 munication with European waters. An example of this is Productus 

 giganteusX Martin, which is common in Europe, and is found in the 

 Lower Carboniferous of the McCloud river, Shasta county, but is not 

 found east of that place, unless P. latissimus Sowerby, from Montana, 

 west of the main chain of the Rocky mountains, be an equivalent. 

 Another example is Omphalotrochus wMtiwyi Meek, which was first de- 

 scribed from the Carboniferous limestone of Shasta county, California, 

 but is also very common in the Lower Coal Measure limestone (C2) of 

 eastern Russia.^ 



On the other hand, many species seem to be confined to, or character- 

 istic of, this ocean ; among them may be mentioned Productus corn 

 d'Orbigny, which Waagen|| says is not found in Europe, its nearest rep- 

 resentative being Productus riparius Trautschold ; it was however first 

 described from South America. 



Goniatltes marianus Verneul is found in the Artinsk region of the 

 Urals and in Arkansas. The genus Pronoriles, while found in western 

 Europe, is rare in it, and is much more common in the Pacific region. 

 Pronoritcs is found in the Artinsk region and in Arkansas, while the 

 ammonite genus Medlicottia, the direct descendant of Pronorites, is 

 found in the Permo-Carboniferous strata of Sicily, the Urals, the Salt 

 range, and Texas. 



It is impossible to suppose that the same genus and species originated 

 at different localities, and since we have both ancestors and descendants 

 in places so widely separated, we can only suppose that there was free 

 interchange of life between those places at that time, or in other words 

 an open sea, on the borders of which these fossiliferous deposits were 

 laid down, and along the margin of which the cephalopods and other 

 marine animals could migrate. 



* Sucss, Antlitz der Erdc, ii, p. 17. 

 tSuess, Ibid., ii, p. 316. 



X See Annual Report U. S. Geog. and Geo!. Surv. Terr., 1883, Part i, p. 132, and Bull. Geog. 

 and Geol. Surv. Terr., Vol. ii, No. -1, p. 354. 

 g See Journal Grol., Vol. ii, No. 6, pp. 59,S-600. 

 11 Pal. Indica, Salt Range Fossils, Brachiopoda, p. 677. 



