of the Devonian of Western Tennessee. 743 



mation is extremely fossiliferous, and the perfect preser- 

 vation of its fossils is scarcely to be duplicated in the 

 whole of the Lower Devonian. Brachiopods greatly 

 predominate, except in a narrow zone at the top of the 

 formation in Benton and Decatur counties which is 

 extremely crowded with bryozoa. Some of the more 

 important fossils are : Pteurodictyum tenticulare, Favo- 

 sites conicus, F. foerstei n. sp., Edriocrinus pocilliformis, 

 Orthostrophia strophomenoides, Dalmanella subcarinata, 

 D. perelegans, D. eminens, Rhipidomella oblata, R. emar- 

 ginata, Bilobites various, Leptostrophia beckii, Leptce- 

 nisca adnascens, L. concava, Anastrophia verneuili, 

 Gypidula multicostata n. sp., Eatonia tennesseensis 

 n. sp., Camarotoechia bialveata, Rensselcerina mediopli- 

 cata, Eospirifer macro pleura, Delthyris perlamellosa, 

 Spirifer cycloptera, Trematospira simplex, T. costata, 

 Meristella arcuata, M. atoka, M. Icevis, Phacops logani, P. 

 hudsonica, Dalmanites pleuroptyx, and D. retusus n. sp. 



The very striking resemblance of this fauna to that of 

 the New Scotland of New York has long been recognized. 

 Of the ninety-nine species identified from this forma- 

 tion, sixty also occur in the New Scotland, and among 

 these are almost all the diagnostic species of the latter, 

 especially noteworthy being Eospirifer macropleura. 

 Considering the great distance which separates Tennes- 

 see, and even Maryland, from New York, the correspond- 

 ence in these faunas is unusual and clearly indicates not 

 only an equivalence in age, but the establishment of a 

 rather direct communicating seaway. On the other hand, 

 there are certain elements in the Birds ong fauna which 

 do not recur at this time in the Appalachian trough and 

 which appear to have reached Tennessee through the 

 previously established southern embayment. Such, for 

 example, are the various species of Scyphocrinus with 

 their associated Camarocrini, the genus Rensselcerina, 

 characteristic new species of Eatonia and Gypidula, and 

 Meristella atoka. The Scyphocrini were sequestered 

 somewhere in the southern waters, their bulbs appearing 

 in great abundance in both Oklahoma and Tennessee, 

 and ranging from the Decatur limestone of the Middle 

 Silurian to the top of the Birdsong shale, whereas they 

 only temporarily invaded the Appalachian trough, 

 appearing in a zone near the middle of the Keyser in 

 Maryland and in the Manlius 1 of New York. 



