376 Review of the New York Geological Reports. 



Hudson River Group, (No. 3 of Pennsylvania and Virginia 

 Reports,) embraces the shales and sandstones of Loraine, Frank- 

 ford and Pulaski, together with the Salmon River rocks. This 

 is the group to which the name grauwacke was originally applied ; 

 it has a very wide range and great thickness. Its maximum 

 thickness is not less than seven hundred feet. In New York 

 the group consists of shales and shaly sandstones, with their 

 courses of limestone, the upper portion very fossiliferous. Its 

 lithological character changes, however, going west. The beds 

 in Ohio, which contain similar fossils, consist of grey and green- 

 ish grey marlite, interstratified with blue fossiliferous limestone. 

 In the upper Mississippi, it appears as a magnesian limestone. 



The fossils by which the shales of Pulaski and Salmon River 

 are readily recognized, according to Vanuxem, are here repre- 

 sented. 



Plate 9, p. 65, Vanuxem's Report. 



1. Pterinea carinata. 



2. Cyrtolites ornatus. 



3. Pentacrinites Hamptonii. 

 Both the Pterinea carinata 



and Cyrtolites ornatus occur in 

 the hills at Cincinnati. 



We are not aware of this Pen- 

 tacrinites having yet been found 

 in the West. 



Plate 113, fig. 2. Avicula demissa. 3. Pleurotomaria, {Tur- 

 ritella ohsoleta 7) 4. Orthis testudinaria ? 



This long spiral Pleiirotom,aria, which is found in the soft ar- 

 gillaceous mass near the top of the rock, (grey sandstone of Lo- 

 raine,) is evidently the same which is found in Wisconsin in great 

 numbers, in a stratum near the junction of the magnesian lime- 

 stone and underlying grey limestone. 



The Avicula demissa belongs to the lower part of the grey 

 sandstone, and is also a Cincinnati fossil. 



With regard to the Orthis testudinaria ? it is impossible to 

 decide from figures on its identity with fossils from other locali- 

 ties ; the New York geologists have not yet been able to deter- 

 mine whether it is distinct from a Trenton species, which it 

 closely resembles. 



