MARYLAND GEOLOGICAL SURVEY 281 



Section CUNEOCORBULA Cossmann. 

 CoEBULA iN-siQUALis Say. 

 Plate LXVII, Figs. 6, 7, 8, 9, 10, 11, 12, 13, 14. 



Corbula incequale Say, 1824, Jour. Acad. Nat. Sci. Phila., vol. iv, 1st ser., p. 1.53, 



pi. xiii, flg. 2; — not of Conrad, 1838, Fossils of the Medial Tertiary, p. 6. 

 Corbula cuneata Conrad, 1838, Fossils of the Medial Tertiary, p. h (excl. diag.), pi. 



iii, flff. 2. 

 Corbula incequale Tuomey and Holmes, 18.56, Pleiocene Fossils of South Carolina, 



p. 76, pi. XX, fig. 12. 

 Corbula incequalis Meek, 1864, Miocene Check List, Scaith. Misc. Coll. (183), p. 12. 

 Corbula subcontracta Whitfield, 1894, Mon. xxiv, U. 8. Geol. Survey, p. 88, pi. xv 



flgs. 11-14. 

 Corbula cuneata Harris, 1896, Bull. Amer. Pal., No. .5, pp. 329, 346, pi. xiii, fig. 2; 



not of Say, 1824. 

 ? Corbula (Cuneocorbula) Whitflekli Dall, 1898, Trans. Wagner Free Inst. Sci., vol. 



iii, pt. iv, p. 849, pi. xxxvi, fig. 18. 

 Corbula {Cuneocorbula) huequalis Dall, 1898, Trans. Wagner Free Inst. Sci., vol. iii 



pt. iv, p. 853. 

 Corbula (Cuneocorbula) subcontracta Dall, 1898, Trans. Wagner Free Inst. Sci., vol. 



iii, pt. iv, p. 854. 



Description. — " Shell convex, transversely ovate-trigonal, rough, with 

 unequal coarse wrinkles: anterior margin with a very acute but short 

 rostrum at its inferior termination, separated from the disk by an acute 

 line: base rounded and a little contracted near the anterior angle: um- 

 bones not prominent."' Say, 1824. 



This species is somewhat variable in size, outline, thickness of shell, 

 and strength of ornamentation. Specimens from Church Hill are quite 

 small and agree Avith the types of C. subcontracta. The upper pos- 

 terior angle in Whitfield's fig. 11 is not characteristic, his fig. 12 is 

 much more typical. Between the larger Church Hill specimens, some 

 from Plum Point, and specimens of C. whitfieldi, there seems to be very 

 little, if any, essential difference. Specimens from the Jones AVharf 

 horizon are often more finely striated than those from the Calvert 

 formation, while those from the St. Mary's formation are largest, thick- 

 est and have the most rounded base. All agree in having rather coarse, 

 irregular, concentric undulations. 



Length, 10.5 mm.; height, 7 mm.; diameter, 2.6 mm. — St. Mary's 

 River specimen. 



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



