200 PROCEEDINGS OF THE PALEONTOLOGICAL SOCIETY 



Mississippian, by the absence of many of the commonest fossils of the later 

 Pennsylvanian, and by the presence of a considerable number of species which 

 are restricted to this fauna. It closely resembles the fauna of the Wapanucka 

 limestone of southern Oklahoma and that of the Morrow group in northeastern 

 Oklahoma and northern Arkansas. It is the oldest known marine Pennsyl- 

 vanian fauna in North America. 



The second main faunal group is found in the rocks of the Strawn, Canyon, 

 and lower Cisco. It contains a large assemblage of mollusks, among which 

 are many of the most characteristic and widely distributed species of the 

 period. Because of its very typical development and remarkably perfect 

 preservation in the Wewoka formation of southern Oklahoma, where it has 

 been described excellently by Dr. George H. Girty, this associated group of 

 invertebrates may conveniently be designated as the Wewoka fauna. The 

 composition of the fauna found in the Mineral Wells (upper Strawn) forma- 

 tion in north Texas is almost the same as that of the type Wewoka fauna. 

 The Canyon formations, which are dominantly calcareous, contain a modifica- 

 tion of the Wewoka fauna which is apparently a normal consequent of the 

 clearer waters of this time. In the lower Cisco a recurrence of the typical 

 Wewoka assemblage, with its numerous molluscan species, is seen in the 

 remarkably fossiliferous shales of the upper part of the Graham formation. 

 While this fauna contains a number of species which are restricted to Texas, 

 a very large proportion is identical with the southern Oklahoma species. The 

 stratigraphic divisions in Oklahoma which are faunally equivalent to the for- 

 mations designated in Texas include most or all of the strata from the Atoka 

 to Holdenville, in the Colgate region, and beds below the Ochelata, in north- 

 eastern Oklahoma. In Kansas, Missouri, and States to the north, the faunal 

 group regarded as equivalent to that described in Texas does not range above 

 the Kansas City formation. 



The fossils from the remaining portion of the Texas Pennsylvanian com- 

 prise a faunal group which is distinctive of the closing epoch in the period. 

 It lacks an important element of the Wewoka fauna and is characterized by 

 the appearance of several new species which are abundant and widely dis- 

 tributed in the rocks of the upper Pennsylvanian, some of them living on 

 into the Lower Permian. The middle and upper Cisco which contains this 

 fauna may be correlated closely with the Lansing to Wabaunsee formations 

 of Kansas and their equivalents in adjoining States. 



The lines of division" between these main faunal groups appear to coin- 

 cide with important interruptions in the deposition of sediments in the 

 Pennsylvanian seas of the Midcontinent region and reflect broadly the 

 physical history of the period. There is a considerable stratigraphic break 

 between the Bend and succeeding deposits. The uplift of the Arbuckle 

 Mountains and the spreading of much clastic debris across northern Texas 

 and Oklahoma is associated with the change in the invertebrate faunas which 

 is observed in the later Pennsylvanian. 



The author of the following paper presented interesting observations 

 upon the matter of attachment of the Paleozoic cup corals. Discussion 

 by Messrs. TJlrich, Chad wick, and Bassler. 



