of the Devonian of Western Tennessee. 741 



terminal Flat Gap member. The more important forms 

 of the Ross limestone are : Pleurodictyum lenticular e, 

 Favosites conicus, Edriocrinus pocilliformis, Scyphocri- 

 nus pratteni, S. pyburnensis, and 8. mutabilis (with their 

 corresponding Camarocrini), Rhipidomella oblala, Lep- 

 tostrophia beckii, Stropheodonta planulata, Anastrophia 

 verneuili, Rensselcerina medioplicata, Delthyris perlamel- 

 losa, D. octocostata mut. tennesseensis, Meristeila atoka, 

 M. Icevis, Phacops logani and Dalmanites pleuroptyx. 

 The Bear Branch member contains, in addition, Eatonia 

 eminens, bnt it and the Flat Gap member lack many 

 species which occur in the Ross, especially the Scypho- 

 crini and Camarocrinus. 



Of this fauna of fifty-eight species, fifteen are indig- 

 enous to Tennessee, while twenty elsewhere occur in 

 both the Coeymans and New Scotland, twenty-one being 

 elsewhere confined to the New Scotland and one to the 

 Coeymans. Its relations are therefore with the higher 

 Coeymans and lower New Scotland, but it has more 

 decidedly the impress of the latter. It does not, however, 

 contain a number of significant species such as Dalrnan- 

 ella perelegans, D. eminens, Orthostrophia strophomen- 

 oides, Camarotoechia bialveata, and especially Eospirifer 

 macropleura, which are very distinctive of the New 

 Scotland, and which do occur in the succeeding Birds ong 

 shale. The latter formation is the more exact equiva- 

 lent of the typical New Scotland, and since, therefore, the 

 Olive Hill formation is considerably older, as shown by 

 the interval of erosion which separates these formations, 

 the Olive Hill must be referred to very early New Scot- 

 land time, if, in fact, it does not represent a part of the 

 higher Coeymans. 



The close relation of this fauna to that of the Birdsong 

 shale will be noted below in the discussion of the latter. 



Birdsong formation. — This shaly member of the Lin- 

 den is the best known of the early Devonian formations of 

 western Tennessee, because of its finely preserved fossils. 

 It is the one exposed at Linden and is much better devel- 

 oped west of the Tennessee River and from Perryville 

 northward to the mouth of Big Sandy River. It was 

 provisionally correlated by Foerste (1903) with the 

 Pyburn limestone which he defined in the section at 

 Pyburns Bluff near the southern edge of the state. If 

 this correlation could be substantiated, the name Pyburn 



Am. Jour. Sci. — Fourth Series, Vol. XLVI, No. 276. — December, 1918. 

 36 



