340 SYSTEMATIC PALEONTOLOGY 



Subgenus PARVILUCINA Dall. 



Phacoides (Parvilucina) crenulatus (Conrad). 

 Plate XC, Figs. 10, 11, 12. 



LiH-ina crenulata Conrad, 1840, Fossils of the Medial Tertiary, p. 39, pi. xx, fig. 2. 

 Lucina lens H. C. Lea, 184.5, Trans. Amer. Philos. Soc, vol. ix, p. 240, pi. xxxiv, tig. 



19. 

 Litcina crenulata Tuomey and Holmes, 18.56, Pleiocene Fossils of South Carolina, 



p. 60, pi. xviii, tigs. 14, 15. 

 Lucina crenulata Emmons, 1858, Kept. N. C. Geol. Survey, p. 29], fig. 217 (fig, 



poor). 

 Lucina crenulata Conrad, 1863, Proc. Acad. Nat. Sci. Phila., vol. xiv, p. 577. 

 Lucina crenulata Meek, 1864, Miocene Check List, Smith. Misc. Coll. (183), p. 8. 

 Not Lucina crenulata Whitfield, 1894, Mon. xxiv, U. S. Geol. Survey, p. 63, pi. x, 



figs. 7-15. 

 Phacoides (Parvilucina) crenulatus Dall, 1903, Trans. Wagner Free Inst. Sci., vol. iii, 



pt. vi, p. 1383, pi. Iii, fig. 12. 



Description. — " Shell lenticular, with numerous concentric laminge; a 

 submarginal fold on the posterior side; posterior extremity truncated; 

 cardinal line straight, oblique; beaks central; cardinal and lateral teeth 

 distinct; margin minutely crenulated." Conrad, 1840. 



Shell orbicular in outline and highly convex or elevated; usually 

 rather thin; hinge area not heavy or broad; anterior side not produced. 

 For distinction from P. trisulcatus see remarks under that species. 



Whitfield has figured as L. crenulata some of the smoother and more 

 rounded forms of P. trisulcatus. 



Length, 6.2 mm.; height, 6 mm.; diameter, 1.8 mm. 



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

 St. Mary's Eiver. Choptank Formation. Governor Eun, 2 miles south 

 of Governor Run, Flag Pond, Jones Wharf, Turner, Pawpaw Point, 

 Trappe Landing, Peach Blossom Creek, Dover Bridge, Greensboro, Cor- 

 dova. Calvert ForMxVTION. Chesapeake Beach, 3 miles south of Che.- 

 apeake Beach, Plum Point, Eeed's. 



Collections. — Maryland Geological Survey, Johns Hopkins University. 



Phacoides (Parvilucina) prunus Dall. 

 Plate XC, Fig. 13. 



Phacoides (Parvilucina) prunus Dall, 1903, Trans. Wagner Free Inst. Sci., vol. iii, 

 pt. vi, p. 1384, pi. Iii, fig. 8. 



Description. — " Shell resembling P. crenulatus but flatter, more in- 

 equilateral, with thicker and more regular concentric ribs, no radial 



