200 ANNUAL EECOED OF SCIENCE AND INDUSTRY. 



Hughes and some others in Great Britain, an example which 

 American geologists might follow with advantage. 



Callaway lias studied the Lower Helderberg limestones in 

 New York for the purpose of comparing them with their sup- 

 posed British equivalents, and also with reference to the view 

 put forward by some, in opposition to Hall, that these lime- 

 stones are but an eastern development of the Niagara for- 

 mation. He confirms Hall's determination of the distinctness 

 of the Lower Helderberg both stratigraphically and paleon- 

 tologically, and maintains that the Niagara is really the equiv- 

 alent of the Wenlock, and the Lower Helderberg of the Lud- 

 low of the British Silurian series. 



Claypole has recently discovered in a rock holding the 

 organic remains of the Clinton group, in Preble County, Ohio, 

 the stem of a tree allied to Lepidodendron. The various 

 plant-remains found in the Lower Helderberg of Michigan, 

 and in the Cincinnati group of Ohio, have been carefully stud- 

 ied by Lesquereux, who concludes that we have already in 

 these pre-Devonian formations represented, on a small scale, 

 the flora of the Carboniferous, including the lycopodiaceous 

 genus Psilophyton ; a fern related to Paleopteris ; Spheno- 

 phyllum and Annularia, representing the Calamiteae; and 

 the sigillaroid genus Protostigma, the latter occurring in the 

 Cincinnati group. 



Saporta has lately described a fern from the slates of An- 

 gers, in France, believed to be of about the same horizon as 

 the last. 



The well-known fossiliferous strata of the Falls of the Ohio 

 have lately been discussed by Hall, who concludes that they 

 embrace beds of Niagara age, followed immediately by Up- 

 per Helderberg (Corniferous) limestone. To these succeed 

 about 30 feet of impure limestones, which are the sole repre- 

 sentatives of the 1200 feet of strata, chiefly sandy and argil- 

 laceous, that constitute the Hamilton formation in Eastern 

 New York. Overlying these Hamilton limestones is the 

 Ohio black slate, regarded as the equivalent of the Genesee 

 slate of New York. We remark in this section the entire 

 disappearance both of the Lower Helderberg and the Salina 



formation. 



SALT DEPOSITS. 



In the Record for 1877 was noticed the remarkable devel- 



