Paleontology of Ihc CincUniati Croup. 159 



credited to the Cincinnati rocks. C. bicornis and C. typicalis. 

 Dr. Gurley informs me that in New York the former very 

 rarely ranges above the lower Trenton, and that probably the 

 Cincinnati forms heretofore referred to this species should be 

 called C. typicalis. The two descriptions are, however, in- 

 serted here for comparison. 



I. — C. nicoKNis, Hall, 1847. 



Stipe linear, elongated, compressed, narrow, gradually 

 widening from the base upwards ; one line or less wide ; 

 serrated on both sides ; serratures slightly oblique ; teeth 

 about one-half the width of the stipe, obtuse; axis capillary; 

 base bifurcate, slit extending about one-half way to the axis ; 

 about one-half as thick as wide, round on one side, flat on the 

 other, often covered with carbonaceous material. (Pal. of 

 New York, vol. i, 1847, p. 268, as Graptoliilnis bicornis). 



Locality. — Cincinnati (?). 



Roitarks. — For remarks on this species see under the 

 generic description above. 



2. — C. TvpicALis, Hall, 1865. 



Stipe linear, serrated on both sides ; orifices sunk beneath 

 the surface of the polypary, transversly oval, or, when flat- 

 tened, rectangular or slightly oblique and semi-oval; axis 

 filiform, central or sub-central and apparently solid ; cellules 

 joined to the axis at the base, the cell partitions consisting of 

 triangular plates, with an unequal arching or convex upper 

 surface, and a concave lower surface ; at the base of the 

 cellules and along the entire length of the stipe is a longitu- 

 dinal depressed line. 



Locality. — Cincinnati. 



Remarks. — This species, while named by Hall in 1865 in 

 Canadian Organic Remains, (Grap., of Quebec Group,) 1865, p. 

 57, and explanation of plate A, is not expressly defined by 

 him. Consequently the description above given has been 

 compiled from remarks made in the course of the discussion 

 of C. bicornis on pages 29-30. On plate A nine figures of the 

 species are given. Nicholson rather questions the absence of 

 a vertical septum in this species, saying it is certainly present 

 in the type species of the genus, and in all others examined 



