344 SYSTEMATIC PALEONTOLOGY 



C. arata was described by Conrad from Newbern, N. C. and from 

 Dover Bridge (near Easton), Md. The figure and description fit the 

 stouter, shorter southern Miocene species with its fewer ribs and short 

 hinge-line, but does not fit the forms found by the writer at Dover 

 Bridge or any other Maryland Miocene horizon. He believes that the 

 Maryland forms referred by Conrad in 1832 to C arata were different 

 from the common Carolina form, C. arata, of which C. carinata is a 

 synonym merely, and belonged to the then undifferentiated species G. 

 protracta which occurs abundantly at Dover Bridge and was first de- 

 scribed by Conrad in 1843. The latter is proportionally longer, thinner, 

 with more numerous ribs and has more nearly linear and parallel dorsal 

 and ventral margins. 



Length, 39 mm.; height, 18 mm.; diameter, 7 mm. 



Occurrence. — Choptank Formation. Governor Eun, 2 miles south 

 of Governor Eun, Flag Pond, Jones Wharf, Dover Bridge, Greensboro. 

 Calvert Formation. Fairhaven, Plum Point, Magruder's Ferry, 

 Church Hill, 3 miles west of Centerville. 



Collections. — Maryland Geological Survey, Johns Hopkins University. 



Genus VENERICARDIA Lamarck. 



Venericardia granulata Say. 

 Plate XCI, Figs. 7, 8, 9, 10. 



Ve7iericardia granulata Say, 1824, Jour. Acad. Nat. Sci. Phila., vol. iv, 1st ser., 



p. 142, pi. xii, fig. 1. 

 Cardita granulata Conrad, 1835, Amer. Jour. Sci., vol. xxviii, p. 110. 

 Cardita granulata Conrad, 1838, Fossils of the Medial Tertiary, p. 12, pi. vii, lig. 1. 

 Cardita granulata Tuomey and Holmes, 1856, Pleiocene Fossils of South Carolina, 



p. 66, pi. xix, figs. 7, 8. 

 Cardita tridentata Emmons, 1858, Kept. N. C. Geol. Survey, p. 302, fig. 236a; not 



of Say, 1826, 

 Actinobolus (Cardita) grarmlata Conrad, 1863, Proc. Acad. Nat. Sci. Phila., vol. xiv, 



p. 578. 

 Venericardia [Cardiocardites) granulata Meek, 1864, Miocene Check List, Smith. 



Misc. Coll. (183), p. 7. 

 Venericardia borealis var. granulata Dall, 1889, Bull, xxxvii, U. S. Nat. Mus., p. 46. 

 Cardita granulata Whitfield, 1894, Mon. xxiv, U. S. Geol. Survey, p. 56, pi. ix, 



figs. 1-4. 

 Venericardia (Cijclocardia) granulata Dall, 1903, Trans. Wagner Free Inst. Sci., vol. 



iii, pt. vi, p. 1431. 



