SIXTH REPORT OF THE DIRECTOR I909 IOI 



Stones River age, since separated as the Pamelia limestone. He 

 attempted to recognize the fucoidal layers in his district, but 

 states that they lie just above the Potsdam instead of occurring 

 at the same horizon as along the Mohawk, and it is plain that 

 the term, as he used it, referred to the passage beds of the 

 Theresa formation, and not at all to the Tribes Hill limestone. 1 



Hall, 1847. I n volume i of the Palaeontology, Hall describes 

 and figures a few fossils from the Potsdam sandstone and the 

 Calciferous sand rock. The Calciferous forms, with the excep- 

 tion ofLingulepis acuminata which is from the basal 

 part, and of four species found loose, came from the upper part 

 of the Little Falls dolomite and from the overlying, calcareous 

 layers (Tribes Hill limestone) along the Mohawk. 



Hall, 1884. 2 Describes Cryptozoon proliferum from 

 the Calciferous of Saratoga county, with description of the genus. 



Walcott, 1879-91. 3 In a series of publications Walcott refers 

 the Potsdam sandstone to the Cambric, describes the fauna from 

 the Hoyt limestone, and recognizes it as Cambric, though re- 

 ferring it at first to the Calciferous. He regards the Hoyt 

 limestone as a local, calcareous phase of the upper part of the 

 Potsdam sandstone and states that Lingulepis acu- 

 minata ranges up into the Calciferous sand rock, and that a 

 species of Ophileta ranges down into the Potsdam. He draws 

 the line between the Cambric and Lower Siluric north of the 

 Adirondacks between the Potsdam and the Calciferous sand 

 rock; about Saratoga in the lower part of the dolomite above 

 the horizon of the Hoyt limestone. 



Comment. Walcott's work was, of course, a great advance over 

 everything that had preceded. We differ from his conclusions 

 chiefly in regarding the Hoyt limestone as on the horizon of the 

 basal portion of the Calciferous rather than of the upper part 

 of the Potsdam; in holding that substantially the same fauna 

 characterizes the upper Potsdam, passage beds, and lower por- 

 tion of the Calciferous; and in classing the whole of the Cal- 

 ciferous of the Saratoga region and all of the Calciferous of the 

 Mohawk valley, except the part here distinguished as the Tribes 

 Hill limestone, with the Potsdam as Saratogan. 



1 Op. cit. p. 270. 



2 N. Y. State Mus. 36th An. Rep't Nat. Hist, pl.6, description. 



8 N. Y. State Mus. 32d An. Rep't. 



Science, 3:136-37. 



U. S. Geol. Sur. Bui. 30, p. 21-22. 



U. S. Geol. Sur. Bui. 81, p. 205-7, 34i _ 47, 363. 



