198 SYSTEMATIC PALEOXTOLOGT 



Description. — " Shell ovate, inflated, rounded before, not much pro- 

 duced, but rapidly tapering to a truncated point behind, furnished with 

 about twelve rather coarse concentric folds or ridges, and a longitudinal 

 gently depressed groove or undulation of surface, running from near 

 the beak to the posterior basal margin; beaks nearly central; anterior 

 series of teeth slightly arched; posterior series nearly straight; margin 

 entire; cavity rather deep." Eogers, 183T. 



Length, 5 mm.; height, 3 mm. 



Occurrence. — Nanjemoy Formation. Popes Creek, Woodstock, 2^ 

 miles above Popes Creek. 



Collections. — Philadelphia Academy of Natural Sciences, Johns Hop- 

 kins University, Maryland Geological Survey. 



Leda cultellipoemis (Eogers). 

 Plate LVI, Figs. 8, 8a. 



JVucula cultdUformis Rogers, 1837, Trans. Amer. Pliilos. Soc, new series, vol. v, 



p. 339. 

 Nucula culteUiformis H. C. Lea, 1848, Proc. Acad. Nat. Sci. Phila., vol. iv, p. 102. 

 Leda culteUiformis Conrad, 1854, Proc. Acad. Nat. Sci. Phila., vol. vii, p. 29.. 

 Miculana culteUiformis Convad, 1»65, Amer. Jour. Conch., vol. i, p. 13. 

 Nuculana culteUiformis Conrad, 1866, Smith. Misc. Coll. (200), p. 3. 

 Nucula culteUiformis Rogers, 1884, Geology of the Virginias, p. 667. 

 Yoldia culteUiformis Clark, 1895, Johns Hopkins Univ. Circ, vol. xv, p. 5. 

 Leda (Adrana) culteUiformis Clark, 1896, Bull. 141, U. S. Geol. Survey, p. 83, pl_ 



xxviii, figs. 3«, '6h. 



Description. — " Shell ovate, ensiform, somewhat inflated, rounded be- 

 fore, much elongated and tapering behind, the posterior length more 

 than twice the anterior, furnished with very line, hardly distinct concen- 

 tric striae, and one distinct and one very obscure rib behind; anterior 

 part with an indistinct fold; shell thin; lunule long and lanceolate; beak 

 small; anterior series of the teeth gently arched; posterior series straight; 

 teeth in both acutely bent, the angles directed toward the beak; margin 

 entire; cavity of shell shallow, with a ridge passing from the beak to the 

 posterior margin." Eogers, 1837. 



Length, 10 mm.; height, 4 mm. 



Occurrence. — Aquia Formation. Clifton Beach. Naxjemoy Foe- 



