1919.] NATURAL SCIENCES OF PHILADELPHIA. 31 



Sculpture. — Axial sculpture appearing, as a rule, on the first 

 coil of the conch in the shape of faint incremental striae, which 

 rapidly strengthen and recur at more and more regular intervals 

 until, by the beginning of the second conchal whorl, there is, in 

 the majority of individuals, a well established axial sculpture of 

 16 to 18 narrow, obtuse, slightly arcuate riblets which are uniform 

 in strength on the early whorls, from the posterior shoulder to 

 the anterior keel which they delicately crenulate; axial sculpture 

 varying in degree of development and persistence from that of 

 the A. styliola sensu stricto to an almost smooth type in which the 

 costals are reduced to feeble undulations faintly visible just pos- 

 terior to the suture line and even feebler wavelets anterior to 

 the suture. Spiral sculpture confined, as a rule, to the base of 

 the body whorl, the pillar, and the anterior canal; periphery of 

 ultima usually outlined by a shallow linear sulcus; base of ultima 

 usually sculptured with 6 to 8 low, half obsolete threads separated 

 by linear interspaces, and, in front of them, 2 less feeble, mor^ 

 widely separated spirals; lirations upon the pillar and anterior 

 siphonal canal normally 9 or 10 in number, well rounded, rather 

 prominent, and close-set; faint traces of spiral lirse visible under 

 high magnification upon other portions of the surface but nowhere 

 sufficiently strong to affect the general aspect of the shell. 



Aperture. — Aperture narrow, lenticular, angulated posteriorly. 

 Outer lip feebly arcuate, obscurely varicose in the adult forms 

 and transversely lirate within. Inner lip contracted at the base 

 of the body whorl. Parietal wall glazed, more or less corrugated 

 in harmony with the spiral sculpture; margin of reflected callous 

 sharp, and standing apart from the pillar wall. Anterior canal 

 moderately long for the genus, recurved, obliquely emarginate. 



Dimensions. — -Altitude, 16.5 mm. Maximum diameter, 4.6 mm. 



Type Locality. — -Natural Well, 1^ miles north of Magnolia, 

 Duplin County, North Carolina. Duplin Formation. 



Observations. — The diagnostic characters of the subspecies are 

 the relatively shallow sutural channel and the more or less obso- 

 lete sculpture, both axial and spiral. It is a rather common little 

 form in the Duplin of the Carolinas. 



Distribution. — Duplin Formation. Natural Well, 1| miles north 

 of Magnolia, Duplin County, North Carolina. Muldrow's Place, 

 5 miles southeast of Mayesville, Sumter County, South Carolina. 



Collections. — U. S. National Museum. Johns Hopkins Uni- 

 versity. Academy of Natural Sciences of Philadelphia. 



