Review of the New York Geological Reports. 379 



The Cypricardia angustifrons is doubtless the same as the 

 Cincinnati species with which it was supposed to be identical. 



The following fossils are also considered characteristic of this 

 group. Cypricardia modiolaris, (fig. 4, pi. 112, p. 377,) C. ovata, 



(p. 378,) Nucula , Orthis Actonim, O. crispata, (fig. 5, pi. 



113, p. 377,) Orthis cequalis, stems of Crinoidea, Graptolites ser- 

 ratus, G. scalaris. Those which are common to this group and 

 the Trenton limestone are, Calymene senaria ? Strophomena se- 

 ricea, Orthis striatula. The Triarthus Beckii has also been 

 found in this formation. 



The Hudson River group, as already remarked, has a wide range; 

 it is, in fact, one of the universal deposites ; but the two masses into 

 which it has been divided, viz. the upper and lower, are not coex- 

 tensive with one another. The lower division or Frankfort slate, 

 is the most persistent mass, being developed both in the valley of the 

 Hudson and Mohawk, while the upper Pulaski and Salmon River 

 shales and sandstone are fully developed only in the latter region. 

 The width of the belt of country occupied by the Hudson 

 River group, is considerably greater than that of any of the pre- 

 ceding members of the Champlain division. In the valley of 

 the Hudson, its average width is about twenty-five miles. 



Between New Jersey and the Great Bend of the Hudson, it 

 ranges nearly north and south, passing thence in a curve to Lake 

 Ontario, whose general direction is northwest, up the valley of the 

 Mohawk and down that of Black River. 



According to the report of Prof. M. an anticlinal axis ranges 

 from near New Baltimore, by Saratoga Lake, to Baker's Falls. 

 East of this axis the strata of this group are upturned and con- 

 torted, and dip to the east southeast. West of it they are but lit- 

 tle disturbed. The same beds on the west side of the axis have 

 a different aspect on the east side. The cause which deranged 

 their position, has also modified their mineralogical character. 



The lower argillaceous rocks of this group, afford in some 

 places a fire-stone suitable for lining furnaces and fireplaces; some 

 °f it might also be employed for roofing slates, but none is wrought 

 for this purpose. Anthracite in small particles occurs in the gray- 

 Wacke of this group. Veins traverse the rocks filled with quartz, 

 carbonate of lime and satin spar. Near the falls of Salmon River, 

 the gray sandstone of this group affords grindstones. Near Red 

 Hook village and Hyde Park, the slaty grits are worked into flag- 

 ging stones. The upper fossiliferous portion of the Hudson River 



