THE FACTS 381 



lock limestone and the shales underlying the Wenlock limestone of 

 England. 



NIAGARA GROUP OF HALL AS REPRESENTED IN THE ROCHESTER SHALE OF 



HARTNAGEL, 1907 



Examination of species listed by Hall in 1852 from the Niagara group 

 (Paleontology of New York, volume ii) shows a list of 18 Brachiopods 

 at that time regarded by Hall as either identical or closely related to 

 Wenlock species of the English section. Later investigations have re- 

 sulted in calling some of them specifically distinct. In the list of species 

 of the fauna of the Rochester shale recently prepared by C. A. Hartnagel, 

 8 of them are definitely recognized and 3 others are sufficiently close to 

 be regarded for correlation purposes as representatives of the same fauna, 

 namely : 



Pholidops squamiformis Hall = P. imbricata Sowerby. 



Atrypa bidentata Hisinger. 



Atrypa plicatella ? Hall = #%. Borealis Schl. (Davidson). 



All of these 11 species of Brachiopods of the Eochester shale are listed 

 from the British Wenlock limestone and also from the Wenlock shale. 

 Two of them (Spirifer sulcatus and Rhynchonella borealis) do not ap- 

 pear above the Wenlock limestone. Below the Wenlock shales 8 of them 

 appear in the Woolhope limestone, 8 (with one doubtful) in the Upper 

 Llandovery, and 7 of them range below into the Ordovician or Lower 

 Silurian, namely, 7 in the Lower Llandovery, 4 in the Caradoc, and 2 in 

 the Llandeilo. Above the Wenlock limestone, 8 appear in the Lower 

 Ludlow, 4 and 1 doubtful in the Aymestry, and 3 in the Upper Ludlow. 

 Here again the correlation is clearly with the Wenlock, and by the evi- 

 dence of identical Brachiopods alone the W r enlock shales and the Wenlock 

 limestone contain the same number of species. 



COMPARISON OF THE EDMUNDS AND ROCHESTER FAUNAS 



Thus by their identical transatlantic species the Edmunds fauna of 

 Maine and the Rochester shale fauna of New York are both found to 

 represent the Wenlock fauna of England. But on direct comparison of 

 the Edmunds and Rochester it appears clear that they are not identical 

 faunas. 



Confining our attention now to Brachiopods exclusively, we find (> oi' 

 the transatlantic species of the Edmunds fauna also appear in the Roch- 

 ester fauna, namely, Pholidops implicata, Dalmanella elegatttula, Rhipi- 

 domella hybrida, Leptcena rhomboidalis, Spirifer crispus, and Atrypa 

 reticularis. 



