Maryland Geological Survey 323 



specimen, which makes the rock look particularly like our Agoniatite 

 limestone." The Agoniatite limestone is found in the lower part of the 

 Marcellus shale in New York extending geogi'aphically from Schoharie 

 County on the east to about the meridian of Phelps, Ontario County, on 

 the west. Stratigraphically as described by Dr. Clarke it descends in the 

 shale toward the west from a horizon in the east fifty feet above the 

 summit of the Onondaga limestone until it reaches and probably enters 

 that limestone.^ The occurrence of a similar lithologic limestone in Mary- 

 land in the upper part of the black Onondaga shales, which also contains 

 the characteristic Goniatite of the New York limestone — Agoniatites ex- 

 pansus (Vanuxem)— is an interesting fact. 



Occurrence. — Romney Formation, Onondaga Member. B. & 0. 

 K. E. cut at 21st Bridge ; W. Va. Cent. E .E. cut at 21st Bridge ; Williams 

 Eoad, 31^ miles southeast of Cumberland. 



Collections. — Maryland Geological Survey ; New York State Museum ; 

 American Museum of Natural History. 



Suborder EURYCAMPYLE 

 Family MAGNOSELLARIDAE 



Genus PARODICERAS Hyatt 



Parodicekas discoideum (Conrad) 

 Plate XLII, Figs. 7, 8 



Ooniatites discoidcus Hall, 1S60, 13th An. Rep. N. Y. State Cab. Nat. Hist., p. 



97, figs. 4-6, p. 98. 

 Ooniatites discoideus Hall, 1879, Nat. Hist. N. Y. Pal., vol. v, pt. ii, p. 441, pi. 



71, figs. 1-13; pi. 74, figs. 4-5. 



Description. — " Shell depressed orbicular in the young state, becoming 

 discoid in its advancing growth and varying conditions of preservation. 

 In young shells the transverse and lateral diameters are about as 5 to 10, 

 11 to 20, and 12 to 24; in a medium-sized specimen, preserving its natural 

 proportions, the two diameters are as 17 to 46. A specimen, which is 

 perhaps somewhat compressed, has a lateral diameter of 60 mm., with a 



> Bull. N. Y. State Mus., No. 49, 1901, p. 137. 



