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228 MOLLUSCA FROM MIOCENE AND LOWER PLIOCENE OF VIRGINIA AND NORTH CAROLINA
keel, which they delicately crenulate; axial sculpture
ranging in degree of development and persistence :from
that of A. styliola s. s. to an almost smooth type in
which the costals are reduced to :feeble undulations
:faintly visible just posterior to the suture line and even
:feebler wavelets anterior to the suture. Spiral sculpture
confined, as a rule, to the base o£ the body whorl,
and the pillar; periphery of final whorl usually outlined
by a shallow linear sulcus; base sculptured with
6 to 8 low, half-obsolete threads separated by linear
interspaces, and in front of them, 2 less feeble, more
widely separated spirals; normally 9 or 10, well
rounded, rather prominent and close-set lirations on
the pillar and anterior fasciole ; faint traces of spiral
lirae visible under magnification on other parts of
the surface but nowhere sufficiently strong to affect the
general aspect of the shell. Suture distinct but inconspicuous;
anterior sulcus of preceding whorl commonly
visible behind it. Aperture narrow, lenticular, angulated
posteriorly. Outer lip feebly arcuate, obscurely
varicose in the adult forms an,d transversely lirate
within. Inner lip contracted at the base of the body
whorl. Parietal wall glazed, roughened in harmony
with the spiral sculpture; margin of reflected callus
sharp, standing apart from the pillar wall. Anterior
canal moderately long for the subgenus, recurved, obliquely
emarginate.
Dimensions of holotype: Height, 16.6 mm.; maximum
diameter, 4.8 mm.
Holotype: U.S.N.M. 114216.
Type Locality: Natural Well, 2 miles southwest of"
Magnolia, Duplin County, N. C. Duplin marl.
The diagnostic characters of the subspecies are the
relatively shallow sutural channel and the more or less
obsolete sculpture, both axial and spiral.
The range of variation in relative dimensions as well
as in sculpture is wide. A stout, strongly costate individual
(U.S.N.M. 325414) is illustrated in figure 29.
The decollated specimen is 11.4 mm. high and 4.2 mm.
in diameter. It was collected at the F. M. Wilson marl
pit, 1 mile east of Magnolia, Duplin County, N. C.
The subspecies is rather abundant in the marls of
Duplin County and also is present in the Duplin of
Sumter County, S.C.
Anachis (Thiarinella) virgilina Gardner, n. sp.
Plate 30, figures 33, 40
Shell heavy, relatively high. Spire elevated. Body
whorl slender, rather abruptly constricted at the base.
Volutions 8 to 9 in all, those of the conch narrowly
tabulated posteriorly, flattened laterally, undercut anteriorly.
Protoconch of 11/ 2 to 2 smooth coils, the
initial half turn somewhat oblique, immersed at the
tip; final turn of protoconch erect, moderately convex.
Axial sculpture well developed, consisting of 18 to 20
narrow, rounded, often feebly arcuate, rather promi-
nent costals which tend to become obsolete on the last
half turn of the body; approximately uniform in
strength from the posterior tabulation of the whorl to
the anterior undercut, and on the body whorl abruptly
evanescent at the shallow sulcus which outlines the periphery.
Spiral striations faintly visible over the entire
surface in the young forms but confined in the adults,
to the peripheral sulcus, the feeble, half-obsolete striations
upon the base, and the 9 to 12 vigorous and
crowded lirations upon the pillar and anterior canal.
Suture line distinct but not conspicuous; channel behind
the suture persistent from the protoconch to the aper- '
ture, well-defined, feebly undulated by the remnants
of the axial costae, its depth corresponding to the width
of the posterior shoulder of the succeeding whorl, so
that the outline of the spire is uniform except for the
recurrent notches at the suture. Aperture narrow,
rudely lenticular, angulated posteriorly. Labrum
gently arcuate, lirate within. Labium obliquely constricted
at the base of the body whorl. Parietal wall
heavily glazed, the outer edge of the enamel sharp and
standing apart :from the pillar. Columella more or
less corrugated in harmony with t4e spiral sculpture.
Anterior canal moderately long, approximately
straight, obliquely emarginate anteriorly.
Dimensions of holotype : Height, 18.5 mm. ; maximum
diameter, 6. 3 mm.
Holotype: U.S.N.M. 325412.
Type locality: Eight to 9 miles southeast of Greenville,
Pitt County, N. C.
Anachis virgilina is separated from the closely allied
and possibly descendant form, A. styliola Dall, by
the heavier, stouter shell ; the more conspicuous axial
sculpture; the spiral sculpture, almost or altogether
. obsolete except on the area in. front of the periphery
of the body whorl; and by the deeper channel behind
the suture and the slightly wider tabulation in front o£
it. The former is limited in its distribution to the Miocene
Chesapeake group of Virginia and North Carolina,
the latter to the Miocene Duplin marl and the
Pliocene Waccamaw formation of the Carolinas.
Distribution: Virginia: St. Marys formation, 1 to 2 miles below
Bowlers Wharf, Essex County.
North Carolina: Yorktown formation, 8 to 9 miles southeast
of Greenville, Pitt County, 2lh miles northwest of Chocowinity
and 1 mile northeast of Chocowinity, Beaufort County.
Subgenus COSTOANACHIS Sacco
1890. Oostoanaohis Sacco, I Molluschi dei Terreni Terziarii del
Piemonte e della Liguria, pt. 6, p. 57.
Type by subsequent designation (Pace, Malacol. Soc. London
Proc., vol. 5, p. 43, 1902) : OoZumbella (Anachis) turrita Sacco.
Miocene, of northern Italy. ·
0 ostoanachis includes the less slender, axially costate
and spirally striate forms. The anterior canal is very
short or rudimentary and the anterior extremity emarginate.
In some species, the outer lip is definitely vari-