312 SYSTEMATIC PALEONTOLOGY 



Length, 112 mm. ; height, 90 mm. ; diameter, 84 mm. 



Occurrence. — St. Mary's Formation (?). Cove Point (?). Chop- 

 tank Formation. Governor Eun, 2 miles south of Governor Kun, Flag 

 Pond, Jones Wharf, Turner, Cuckold Creek, St. Leonard Creek, Dover 

 Bridge, Peach Blossom Creek, Greensboro. Calvert Formation. 

 Chesapeake Beach, 3 miles south of Chesapeake Beach, Plum Point, 

 Church Hill. 



Collections. — Maryland Geological Survey, Johns Hopkins University. 



Genus CALLOCARDIA A. Adams. 

 Subgenus AGRIOPOMA Dall. 



Callocardia (Agriopoma) subnasuta (Conrad). 

 Plate LXXV, Figs. 1, 2, 3. 



Cytherea subnasuta Courad, 1841, Proc. Acad. Nat. Sci. Phila., vol. i, p. 28. 

 Cytherea subnasuta Conrad, 1843, Jour. Acad. Nat. Sci. Phila., vol. viii, 1st ser., 



p. 183. 

 Cytherea subnasuta Conrad, 1845, Fossils of the Medial Tertiary, p. 72, pi. xli, fig. 3. 

 Ve7ius subnasuta d'Orbigny, 1852, Prod. Pal. Strat., vol. iii, p. 108, No. 2034. 

 Venus subnasuta Tuomey and Holmes, 1856, Pleiocene Fossils of South Carolina, 



p. 80, pi. xxi, fig. 3. 

 Dione subnasuta Conrad, 1863, Proc. Acad. Nat. Sci. Phila, vol. xiv, p. 575. 

 ■ Dione subnasuta Meek, 1864, Miocene Check List, Smith. Misc. Coll. (183), p. 10. 

 Callocardia {Agriopoma) subnasuta Dall, 1903, Trans. Wagner Free Inst. Sci., vol. iii, 



pt. vi, p. 1264. 



Description. — " Trigonal, thin, ventricose ; anterior side narrowed, 

 slightly produced and subangulated at the extremity ; surface with rather 

 prominent concentric wrinkles ; posterior margin obliquely arched ; beaks 

 distant from anterior extremity, and not nearly central ; length 1^ inch. 

 Allied to C. Sayana, but is proportionally longer, less ventricose, nar- 

 rowed, and more produced anteriorly .'' Conrad, 1841. 



See also remarks under C. say ana for additional distinctions between 

 the two species. 



Length, 30 mm. ; height, 24 mm. ; diameter, 8.5 mm. 



Occurrence. — St. Mary's Formation. Cove Point, Langley's Bluff, 

 St. Mary's Kiver. Choptank Formation. Jones Wharf, Dover Bridge, 

 Calvert Formation. 3 miles south of Chesapeake Beach, Plum Point. 



GoZZec^ions.— Maryland Geological Survey, Johns Hopkins University. 



