of the Devonian of Western Tennessee. 749 



The relation of this fauna to that of the upper Oriskany 

 in the Appalachian trough is very striking, especially in 

 consideration of the great distance of over 600 miles 

 which separates these regions. Nineteen of the twenty- 

 five species found in Tennessee occur elsewhere in the 

 upper Oriskany, thirteen of them being common to both 

 Maryland and New York, and these include almost all the 

 distinctive Oriskany forms. The distinctness of this 

 fauna from that of the Linden group below is shown by 

 the fact that only one species, the long-ranging Eatonia 

 peculiaris, has been found in both. 



The fauna of the Little Saline limestone of Missouri, 

 discovered by Weller -(1914), has not yet been described, 

 and Weller 's report is awaited with great interest. Nev- 

 ertheless a preliminary comparison made by the writer 

 with a collection sent to Yale by Professor Weller indi- 

 cates that the Missouri fauna is less closely related to 

 that of the Harriman novaculite than either of these is 

 to that of the Appalachian trough. 



Middle Devonian Series 

 Ulsterian Group 



The earlier Middle Devonian or Ulsterian is repre- 

 sented in Tennessee by two formations, the Camden chert 

 and the Pegram limestone. The former is well devel- 

 oped in the northern half of the valley, where it attains a 

 measured thickness of 164 feet, while the latter is a very 

 thin formation of which only remnants are now exposed 

 at three widely separated localities. 



Camden chert. — This formation was named by Saff ord 

 and Schu chert (1899) for the village of Camden, Ten- 

 nessee, where it is typically developed and well exposed. 

 Although previous workers have regarded it as an Oris- 

 kany formation, it is one of the chief conclusions of the 

 present study that it forms an early part of the Middle 

 Devonian. When first described, it was referred to the 

 lower Oriskany, and attention was especially directed to 

 the absence here of the large brachiopods which char- 

 acterize the upper Oriskany. When in 1907 Savage 

 restudied the equivalent of these beds in Illinois, where 

 they are known as the Clear Creek chert, he showed that 

 they pass apparently by continuous deposition into the 

 Grand Tower (Onondaga) formation, there being an 



