MARyLAND GEOLOGICAL SURVEY 295 



from the S. carinata by having " a somewhat more elongated form and 

 more uniform and close-set sculpture, especially over the posterior dorsal 

 area. The size of those collected is also smaller than that of the full- 

 grown Miocene specimens/' 



Occurrence. — St. Mary's Formation. St. Mary's River. Choptank 

 Formation. Jones Wharf. 



Collection. — Maryland Geological Survey. 



Semele subovata (Say). 

 Plate LXXII, Figs. 6, 7, 8. 



Amphidesma subomta Say, 1834, Jour. Acad. Nat. Sci. Phila., vol. iv, 1st ,ser., j). l.')2, 



pL X, fig. 10. 

 Amphidesma mhovata Conrad, 1840, Fossils of the Medial Tertiary, p. 30. 

 Syiidosmya snbobliqua Conrad, 18.54, Proc. Acad. Nat. Sci. Phila., vol. vii, p. 29. 

 Abra ovalis Conrad, 1862, Proc. Acad. Nat. Sci. Phila., vol. xiv, p. 288. 

 Ab7-a subovata Conrad, 1863, Proc. Acad. Nat. Sci. Phila., vol. xiv, p. 574. 

 Abra subovata Meek, 1864, Miocene Check List, Smith. Misc. Coll. (183), p. 11. 

 Semele subovata Dall, 1900, Trans. Wagner Free Inst. Sci., vol. iii, pt. v, p. 990. 



Description. — " Shell transversely ovate-oval, with somewhat promi- 

 nent and regular concentric striae. 



"Shell compressed; beaks rather before the middle, but little promi- 

 nent; anterior submargin with an obsolete, obtuse undulation; lunula 

 lanceolate; cardinal and lateral teeth prominent." Say, 1824. 



This species may be distinguished from 8. carinata by having all of its 

 concentric striae of about equal prominence and by having a somewhat 

 more elongated and thinner shell. Lateral teeth in left valve not promi- 

 nent, in the right prominent. 



Length, 20.5 mm. ; height, 14 mm. ; diameter, 3 mm. 



Occurrence. — St. Mary's Formation. Cove Point, St. Mary's River. 

 Cjioptank Formation. Governor Run, 2 miles south of Governor Run, 

 Jones Wharf, Peach Blossom Creek, Dover Bridge, Greensboro, Cordova. 

 Calvert Formation. Fairhaven, 3 miles west of Centerville, Church 

 Hill. 



Collections. — Maryland Geological Survey, Johns Hopkins University. 



