28 PKOCEEDINGS OF THE ACADEMY OF [Feb., 



rather sharply constricted at the base. Suture distinct, not con- 

 spicuous, gently undulated by the axial ribs of the preceding whorl. 

 Protoconch. — Protoconch"small, smooth, acutely tapering, pauci- 

 spiral, although the exact number of turns can not be determined 

 because of the decortication of the apex. 



Sculpture.- — Axial sculpture of prominent, rounded ribs and of 

 incrementals visible only under magnification; costse 7 or 8 to 

 the whorl, rounded, though sharply defined, conspicuous eleva- 

 tions, which, on the spire, persist from suture to suture, although 

 strongest on the periphery; body costse rounded on the summits, 

 the sides almost vertical, gradually flattening as they approach 

 the canal; prominence of the costse greatly increased by the pecu- 

 liar spiral lirations which cross them. Primary spirals 3 or 4 

 in number upon the whorls of the spire, broad and low and very 

 flat in the intercostal areas and on the sides of the costse; lirse 

 abruptly thickening, however, upon the summits of the costals 

 thereby throwing the intercostal areas into relief and apparently 

 increasing the elevation of the costse; secondary spiral lirations 

 narrow, flat bands less than one-half as wide as the primaries 

 and separated from them by interspaces the width of the former; 

 secondaries not increasing in prominence as they cross the axials; 

 posterior fasciole rather wide, sculptured with an anterior second- 

 ary, 2 or 3 primaries of uniform elevation and without intercalated 

 secondaries, together with a broad, pre-sutural ribbon equal to 

 the primaries in altitude and exceeding them in breadth; body 

 whorl ornamented with 12 primaries; secondaries intercalated on 

 the posterior portion but absent anteriorly; anterior fasciole dif- 

 ferentiated but not prominently keeled, sculptured with 5 to 8 

 crowded lirse. 



Aperture. — Aperture ovate-elongate. Labrum arcuate, fur- 

 nished with 8 or 9 sharp plications upon the surface. Columella 

 concave, smooth, calloused. Canal short, slightly recurved, emar- 

 ginate. 



Dimensions. — Altitude, 20.7 mm. Maximum diameter, 7.2 mm. 



Type Locality. — Muldrow's Place, 5 miles southeast of Mayes- 

 ville, Sumter County, South Carolina. Duplifi Formation. 



Observations. — Phos sloani is known only from Sumter County, 

 South Carolina, and is quite unlike any described form. It is 

 characterized by the peculiar, abrupt increase in the prominence 

 of the spirals as they mount the summit of the costals, so that 

 the intercostals have the appearance of being smoothly scooped. 



