MARYLAND GEOLOGICAL SURVEY 399 



Nucula proxima Tuomey and Holmes, 1856, Pleiocene Fossils of South Carolina, 



p. 53, pi. xvii, flgs. 7-9. 

 Nucula proxima Emmons, 1858, Kept. N. Car. Geol. Survey, p. 287, fig. 20SB. 

 Nucula proxima Dall, 1889, Bull, xxxvii, U. S. Nat. Mus., p. 43, pi. Ivi, fig. 4. 

 Nucula proxima Whitfield, 1894, Mon. xxiv, U. S. Geol. Survey, p. 50, pi. vii, tigs. 



7-10. 

 Nucula proxima Dall, 1898, Trans. Wagner Free Inst. Sci., vol. iii, pt. iv, p. 574. 



Description. — " Shell subtriangular, oblique, concentrically wrinkled, 

 and longitudinally marked with numerous, hardly perceptible striae; pos- 

 terior margin very short and very obtusely rounded, a submarginal im- 

 pressed line; anterior margin very oblique and but slightly arcuated; 

 umbo placed far back; within perlaceous, polished, edge strongly crenated; 

 teeth of the hinge robust, the posterior series very distinct and regular. 



" Very much resembles N. nucleus, but is proportionally wider, and the 

 posterior series of teeth is more regular and distinct. It may possibly 

 prove to be only a variety, when numerous specimens are carefully exam- 

 ined and compared." Say, 1823. 



Those from Church Hill are much larger than those from the other 

 localities given below, the measurements being : length, 12 mm. ; height, 

 10.5 mm.; diameter, 4 mm.; and length, 6.5 mm.; height, 5.3 mm.; 

 diameter, 2.1 mm., respectively. 



Occurrence. — Choptank Formation. Dover Bridge, Cordova. Cal- 

 vert Formation. Church Hill, 3 miles Avest of Centerville, Fairhaven, 

 3 miles south of Chesapeake Beach, Plum Point, Truman's Wharf. 



Collections. — Maryland Geological Survey, Johns Hopkins University, 

 U. S. National Museum. 



Nucula sinaria Dall. 

 Plate CVIII, Figs. 7, 8. 



Nucula sinaria Dall, 1898, Trans. Wagner Free inst. Sci., vol. iii, pt. iv, p. 575, 

 pi. xxxii, fig. 7. 



Description. — " Shell small, solid, trigonal, polished, with fine, radial 

 strias, more distinct near the basal margins, and faint, concentric, rather 

 irregular furrows, obsolete over most of the valve, but tending to be 

 stronger near the anterior and posterior slopes; here and there one 

 crosses the whole shell like the indication of a resting stage; dorsal 

 slopes nearly straight, base arcuate, ends rounded; lunule absent, escutch- 



