New Species of Devonian Fossils. 115 



this time, however, the Tennessee faunas retained something of 

 their provincial aspect, for certain highly characteristic forms, 

 such as the Scyphocrini and Camarocrini among the crinoids and 

 RensselcErina medioplicata, Eatonia tennesscensis, Gypidula mul- 

 ticostata and Meristella atoka among the brachiopods, did not 

 spread into the Appalachian trough. Devonian formations hav- 

 ing the same faunal facies as that of the Birdsong shale also 

 occur along the Mississippi River in southwestern Illinois and 

 adjacent parts of Missouri and again further to the west in the 

 Arbuckle uplift of Oklahoma. These occurrences of Helder- 

 bergian strata serve to indicate something of the extent of this 

 southern embayment, whose eastern shore flanked on the western 

 side of the Nashville Dome and lay not far east of the present 

 Western Valley, and whose northern limit extended some dis- 

 tance beyond Cairo, Illinois. 



The equivalence of the Birdsong shale and the New Scotland 

 being evident, it would seem from the stratigraphic relations that 

 the Rockhouse shale has its time equivalent in some part of the 

 Keyser, and that the thick Olive Hill formation is of the age of 

 the Coeymans, if not also of a part of the Keyser. As for the 

 faunal evidence, the fauna of the Rockhouse shale is certainly 

 of very early Devonian age, a fact that is indicated both by 

 Silurian holdovers, as Dictyonella subgibbosa, and by the primi- 

 tive aspect of such Devonian forms as Pleurodictyuni trifoliatum. 

 No faunal relations with the Keyser can be seen, however, for 

 there was at this time no connection with the Appalachian basin. 

 This small fauna has yielded eleven of the new species here 

 described. 



The fauna of the Olive Hill formation is remarkable for the 

 dominance of the Scyphocrini and their associated root-bulbs, 

 the Camarocrini. These crinoids had previously appeared in 

 Tennessee in the Decatur limestone of late Middle Silurian age. 

 They recur in abundance in the Rockhouse shale, are at their 

 climax in the Ross limestone member of the Olive Hill forma- 

 tion, and persist with a few stragglers through the Birdsong 

 shale. They are also extremely abundant in the' Helderbergian 

 of Oklahoma. They are particularly characteristic of this 

 southern embayment, where they must have been sequestered 

 from Middle Silurian well into early Devonian time. During 



