136 STSTEilATIC PALEOXTOLOGY 



A single fragment was found which may safely be assumed to repre- 

 sent this species. 



Lengthy 13 mm. (restored); width, 5 mm. 



Occurrence. — Aquia Foematiox. 1 mile northeast of Piscataway. 



Collection. — ^Maryland Geological Survey. 



Family BUCCINIDAE. 



Genus STREPSIDURA Swainson. 



Steepsiduea subscalaeixa Heilprin, 



Plate XXII, Figs. 5, 6, 7, 8, 8a. 



Fusus (Strepsidura) subscalarimis Heilprin, 1880, Proc. Acad. Nat. Sci. Pliila., vol. 



XXXV, p. 372, pi. XX, fig. 8. 

 Fusus {Strepsidura) perlatus Clark, 189.5, Johns Hopkins Univ. Cire., vol. xv, p. 4. 

 Fusus (Strepsidura} perlatus Clark, 1896, Bull. 141, U. S. Geol. Survey, p. 67. 



Description. — " Shell somewhat bucciniform, whorls about eight, sub- 

 angular, the first three or four smooth, the remainder ornamented with 

 both longitudinal costae and revolving striae, the latter showing a ten- 

 dency to alternate in size; the costae are arcuate, not in a regularly con- 

 tinuous series, those of the body whorl extending considerably below 

 the middle of the whorl; aperture about the length of spire, the canal 

 somewhat reflected; columella covered with a callous deposit, consider- 

 ably twisted; outer lip dentate within." Heilprin, 1880. 



Our specimens show a marked tendency to variation both in shape 

 and sculpture, as the figures show, but none of the forms seem to be 

 sufficiently definite to warrant the separation of another species. 



Occurrence. — Xanjemoy Foematiox. Popes Creek, "Woodstock. 

 Aquia Foematiox. Liverpool Point, Potomac Creek, 2 miles below 

 Potomac Creek, Upper Marlboro. 



Collections. — Maryland Geological Survey, Johns Hopkins University, 

 Philadelphia Academy of Natural Sciences. 



Genus MELONGENA Schumacher. 

 MeLOXGEXA (?) POTOMACEXSIS n. sp. 



Plate XXII, Fig. 9. 

 Description. — Shell fusiform, showing five angulated whorls (the api- 

 cal whorls and portion of the body whorl wanting); with about twelve 



