32'2 SYSTEMATIC PALEONTOLOGY 



Occurrence. FREDERICK LIMESTONE. Frederick, Maryland, and 

 neighboring localities. 



Collection. TJ. S. National Museum. 



Suborder ORTHOCHOANITES 

 Family ORTHOCERATIDAE 



Genus ORTHOGERAS Breynius 



ORTHOCERAS PRIMIGENIUM Vanuxem 



Plate XXXII, Fig. 5 



Orthoceras primigenium Vanuxem, 1842, Geol. New York, 3d Dist., p. 36, 



fig. 4. 

 Orthoceras primigenium Whitfield, 1889, Bull. Amer. Mus. Nat. Hist, vol. ii, 



No. 2, p. 56, pi. x, fig. 1. 

 Orthoceras primigenium Cleland, 1903, Bull. Amer. Pal., vol. iv, p. 14, pi. iii, 



figs. 8, 9. 



Description. In spite of 15 or more references to this cephalopod, the 

 species cannot yet be said to have been sufficiently described for accurate 

 determination. Really this name has been employed for any gradually 

 tapering, straight cephalopod of the Canadian in which the septa are thin, 

 deeply concave, and closely arranged. In the present case the same 

 procedure has been followed, for the identification of this species in Mary- 

 land has been based upon longitudinal sections in the rock showing no 

 other characters than those just mentioned. However, it is believed that 

 this identification will be found correct when specimens from the New 

 York type localities are restudied, since Vanuxem's type came from the 

 Tribes Hill limestone and the Maryland examples are from the corre- 

 sponding formation in that state. 



Occurrence. BEEKMANTOWN LIMESTONE (Stonehenge member). 

 Hagerstown, Maryland, and vicinity. 



Collections. Maryland Geological Survey, U. S. National Museum. 



