168 SYSTEMATIC PALEONTOLOGY 



Family VENERIDAE. 



Genus MERETRIX Lamarck. 



Meretkix lenis (Conrad). 



Plate XXXIII, Fig. 4. 



. Cytherea lenis Conrad, lb48, Jour. Acad. Nat. Sci. Phila., 2nd ser., voL i, p. loO, 

 pL xiv, tig. 19. 



Description. — " Longitudinally ovate, thin, ventricose; anterior ex- 

 tremity acutely rounded; posterior end direct, subtruncated; disk with 

 impressed concentric lines, distinct on the sides but obsolete in the 

 middle of the valves; lunule long, cordate, defined by an impressed line; 

 inner margin entire." Conrad, 1848. 



This species is distinguished from its associates by its extremely ele- 

 vated beaks, and deep valves. The shell is very thin and fragile and 

 tends to break along radiating lines. The concentric wrinkles and lines 

 of growth are very distinct toward the beak, but become less so toward 

 the periphery. 



Length, 11 mm.; height, 11 mm. 



Occurrence. — Xanjemoy Formation. Woodstock, Ravine north of 

 Thrift (?). 



Collections.' — Maryland Geological Survey, Philadelphia Academy of 

 Natural Sciences (No. 6384). 



Meretkix ovata var. ovata (Rogers). 

 Plate XXXIV, Figs. 1, la. 



Cytherea ovata Rogers, 1837, Trans. Amer. Philos. Soc, voL v, p. 840; vol. vi, 

 pi. xxvii, fig. 2. (Reprint GeoL of the Virginias, 1884, p. 668, pi. ii, flg. 2.) 



Cytherea liciata Conrad, 1848, Jour. Acad. Nat. Sci. Phila., 3nd ser., voL i, p. 181, 

 pi. xiv, flg. 20. 



Cytherea ovata H. C. Lea., 1848, Proc. Acad. Nat. Sci. Phila., vol. iv, p. 99. 



Cytherea liciata H. C. Lea, 1848, Proc. Acad. Nat. Sci. Phila., vol. iv, p. 99. 



Mereirix liciata Conrad, 18.54, Proc. Acad. Nat. Sci. Phila., vol. vii, p. 30. 



Meretrix ovata Conrad, 1854, Proc. Acad. Nat. Sci. Phila., vol. vii, p. 80. 



Dione ovata Conrad, 1865, Amer. Jour. Conch., vol. i, p. 6. 



Dione liciata Conrad, 1865, Amer. Jour. Conch., vol. i, p. 6. 



Dione ovata Conrad, 1866, Smith. Misc. Coll. (200), p. 7. 



Dione liciata Conrad, 1866, Smith. Misc. Coll. (200), p. 7. 



Cytherea ovata Clark, 1895, Johns Hopkins Univ. Circ, vol. xv, p. 5. (In j)art.) 



Cytherea ovata Clark, 1896, Bull. 141, U. S. Geol. Survey, p. 76. (In part.1 



