AKT. It FOSSIL MOLLUSKS FROM THE MIOCENE MANSFIELD - 5 



nuclear whorls. Nuclear whorls large, smooth, moderately inflated, 

 constricted at the suture, apical one bluntly rounded. Post-nuclear 

 whorls rather rapidly enlarging and broadly rounded in outline. 

 Suture grooved, not appressed. Sculpture of (on the penultimate 

 whorl, five) slightly raised, paired, spiral lines, the individual lines 

 composing each pair being separated from each other by a narrow 

 groove and the pairs from each other by an interspace about equal to 

 their width. The spirals extend forward to the end of the canal. 

 Very fine axial growth lines connect the paired spirals. xVperture 

 elongate-subovate, outer lip thin, margin crenulate. Pillar at its 

 lower margin j)rovided with a fold, forming the inner and upper 

 edge of the short and curved siphonal canal. The new species may 

 not be mature. 



Dimensions.— Tj^Q (Cat. No. 352438, U. S. N. M.) , altitude, 3.8 mm. ; 

 diameter, l.G mm. ; length of aperture, 1.5 mm. ; width, 0.7 mm, 



Tyi)e locality. — U. S. G. S. station 1/205, uppermost bed in section 

 along a small stream flowing into Tormentor Creek, about 2 miles 

 north of Smithfield, Va. (W. C. Mansfield, collector.) 



Occurrence. — Yorktown formation, zone 2, middle part; only 

 known from type locality. 



EPITONIUM SMITHFIELDENSIS, new species 



Plate 1, figure 10 



Shell of medium size, stout, delicately ornamented with slender 

 varices, consisting of seven remaining whorls — ^nucleus decollate. 

 "Whorls well rounded, gradually and evenly enlarging, and very 

 strongly constricted at the deeply grooved suture. Sculpture of (on 

 the last whorl, 12) wide, very thin, marginally reflected retractive 

 varices, the margins being cuspidate at the posterior third and ends 

 fused to the preceding and succeeding varices. The varices extend 

 diagonally across the whorl and, followed successively up the spire, 

 make about a half-turn around the axis. No other ornamentation is 

 present. Aperture orbicular in shape, outer margin formed by the 

 terminal varix and inner margin by a thin lamina adhering to the 

 varices. 



Dimensions.— Ty^Q (Cat. No. 352440, U.S.N.M.), altitude, 12 mm.; 

 greatest diameter, 5 mm. ; greatest diameter of aperture, 2.2 mm. 



Type locality. — U. S. G. S. station 1/205, uppermost bed in a sec- 

 tion along small stream flowing into Tormentor Creek about 2 miles 

 north of Smithfield, Va. (W. C. Mansfield, collector.) 



Occurrence. — Yorktown formation, zone 2, middle part. Only 

 known from the type locality. 



