INSTITUTE OF SCIENCE, PHILADELPHIA. 421 



MoUeria duplinensis n. s. 

 Plate 23, figure 18. 



Newer Miocene at the Natural Well of Duplin County, N. Car., Burns. 



Shell minute, turbinate, smooth or minutely granulose or shagreened, 

 with four whorls ; nucleus small ; upper surface of the spire evenly rounded ; 

 suture distinct, the last whorl declining a little near the aperture ; periphery 

 and base evenly rounded to the margin of the umbilicus, which is formed by 

 a rather prominent rib, above which the umbilicus is funicular ; aperture 

 circular, its outer margin angulated at the suture and at the end of the umbili- 

 cal rib ; internally the opercular shelf is well marked. Alt. of shell 1.5 ; max. 

 diam. 2.0 mm. 



The surface of this small shell is somewhat worn, but it suggests that, 

 when in perfect condition, it may not be perfectly smooth, but rather micro- 

 scopically sculptured. 



MoUeria minusoula n. s. 



Chesapeake Miocene of St. Mary's River, Maryland, Clark. 



Shell very small, with the general form oi Lunatia interna Say, turbinate, 

 fully rounded, with two and a half whorls ; surface smooth, suture distinct, 

 not deep; base rounded; umbilicus very small; aperture rounded, hardly 

 thickened, the margin internally with a perceptible ledge for the edge of the 

 operculum. Alt. 0.7; max. diam. i.o mm. 



This shell is well distinguished by its extremely small size, smooth sur- 

 face and small umbilical chink. 



Family NERITID^. 



Genus NBRITA (Linne) Bruguifere. 



Nerita tampaensis n. s. 



Plate 17, fijiure 3. 



Older Miocene of the Orthaulax bed, Tampa Bay, Florida, and of the 



Tampa limestone at La Penotiere's Hammock, on Six-Mile Creek, a mile and 



a half south of Orient Station, six miles eastward from Tampa City, Florida, 



Dall and Burns, 



Shell rather small, with a depressed spire and three whorls ; surface 

 varying from nearly smooth with obsolete spiral sculpture to strongly irregu- 

 larly spirally ribbed with narrow rounded ribs separated by wider interspaces 

 and crossed by more or less conspicuous lines of growth ; there is no fine 

 striation and the ribs are extremely irregular in size when strong, and become 

 almost entirely obsolete in some specimens ; they are more sparse on the upper 

 surface than on the periphery; aperture half-moon-shaped, outer lip thickened, 

 but not dentate ; inner lip with a broad, rather thin callus with obscure tuber- 

 cles on the lower portion ; pillar thin, with a few obscure denticles near the 

 rniddle, Alt. lo.o; max. Ion. 12.5 mm. 



