124: SYSTEilATIC PALEONTOLOGY 



dulating in Avidtli; spire short, conical, acuminate; whorls slightly con- 

 vex; body whorl more than half the lengtli of the shell, moderately 

 convex; suture distinct; outer lip sometimes crenulate; columella with 

 two pronounced obliqiie plicae. 



Length, 15 mm.; width, 8 mm. 



Occurrence. — Xax.jemoy Foejiatiox. West of Port Tobacco. Wood- 

 stock, 1 mile southeast of Piscataway. Aquia Formation. Aquia 

 Creek, Potomac Creek, 1 mile northeast of Piscataway, Upper Marlboro. 



Collections. — Maryland Geological Survey, Philadelphia Academy of 

 Xatural Sciences, U. S. Xational Museum. 



Family RINGICULIDAE. 



Genus RINGICULA Deshayes. 



PiixGicuLA DALLi Clark. 



Plate XX, Figs. 3, 3a. 



Singicula dalli Clark, 189.5, Johns Hopkins Univ. Circ, voL xv, p. 4. 



Ringicula dalli Clark, 1896, Bull. 141, U. S. Geol. Survey, p. 64, pi. ix, figs. 3«, ?^b. 



Ringicula dalli Aldrich, 1897, Bull. Amer. Pal. No. 8, p. 8, pi. ii, fig. 6. 



Description. — "' Shell small, five-whorled; surface of last four whorls 

 strongly striate spirally; spire elevated, acuminate; body whorl much 

 inflated; outer lip much thickened and crenulate within; columella with 

 thick callous and with two strong plaits." Clark, 1896. 



Length, 3 mm.; v\ddth, 2 mm. 



Occurrence. — Xax.jemoy FoR:\rATiox. Woodstock. 



Collection. — Maryland Geological Survey. 



Family SCAPHANDRIDAE. 



Genus CYLICHNA Loven. 



Cylicbxa yexusta Clark. 



Plate XX, Figs. 4, 4a. 



Cylichna venuata Clark, 189.5, .Johns Hopkins Univ. Circ, vol. xv, p. 4. 



Cylichna veuusta Clark, 1896, Bull. 141, U. S. Geol. Survey, p. 64, pi. ix, figs. 2a, 2b. 



Description. — "Shell small, elongate-ovate, rather globose; surface 

 spirally striate; spire depressed; cohimella with small obscure plait." 

 Clark, 189G. 



