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Teinostmna and described the species steirata (pl. 25,
fig. 34) as a Teinostoma. The features are distinct from
those of Teinostoma and deserve generic recognition.
The soft parts are not known and probably never will
be since both the American and the European species
seem to be restricted to the Atlantic Tertiary faunas.
Solariorbis includes a compact group of species exceptionally
well characterized by the depressed apical
surface, finely punctate spiral sculpture and rather
large umbilical area surrounding the small umbilical
pit. From the shell characters alone Solariorbis seems
more closely related to Circulus and Oyclostremiscus
than to Teinostoma.
The height of the figured individual (U. S. N. M.
112649) is 1.0 mm., the maximum diameter 2.6 mm. It
was collected on the Cape Fear River from the "Newer
Miocene," which includes both the Duplin marl and the
Waccamaw formation.
Family CYCLOSTREMATIDAE
Genus CYCLOSTREMISCUS Pilsbry and Olsson
1945. Cyclostt·emiscus Pilsbry and Olsson, Acad. Nat. Sci. Philadelphia
Proc., vol. 97, p. 266.
Type by original designation: Vitrinella panamen.sis C. B.
Adams. Recent, off the West Coast of Panama and Mazatlan.
The shell is small or minute (usually less than 3 mm. in
diameter), solid _or moderately strong, depressed or discoidal,
much wider than high, umbilicate, of few (about 3 more or
less) whorls, of which the first 11h to 2 form a smooth nuclear
shell. Last whorl typically having several spiral angles or
carinae, their intervals typically with lower axial riblets or
striae. Aperture subcircular or modified by the angles of the
shell, the peristome continuous, not thickened externally. Type
Vitrinella panamen.sis C. B. Adams.
We introduce this genus for a series of small or minute
species, abundantly represented in the west American tropics.
Some of them have been described in the genera Vitrinella and
Oyclostrema, but in our opinion the differences outweigh such
similarity as may be traced * * *.
The living animal, operculum and radula have not been observed.-Pilsbry
and Olsson, 1945.
Oir(}ul'IJJ8 Jeffreys is available for the small discoidal
spirally keeled forms and Oyclostremiscus may be restricted
to the cancellate shells at least until the ani-.
mals have been studied.
Cyclostremiscus oblique-striatus (H. C. Lea)
Plate 25, figures 31, 32
1843. Delphinula oblique-striata H. C. Lea, Am. Philos. Soc.
Proc., vol. 3, p. 164 ( n. n.) .
1846. Delph-inula oblique-striata H. C. Lea, Am. Philos. Soc.
Trans., n. ser., vol. 9, p. 261, pl. 36, fig. 72.
1892. Adeorbis? obliquistriata (H. C. Lea). Dall, Wagner Free
Inst. Sci. Trans., vol. 3, pt. 2, p. 347
Shell orbicular, depressed, thick, diaphanous, sub-cancellate;
spire very short, ovate, longitudinally and deeply sulcate near
the apex; sutures impressed, linear; whorls four, convex; sulculi
longitudinal, nearly obsolete at the lower suture; straie
obliquely transverse, small, numerous; last whorl sometimes
carinate, sometimes angulate, smooth near the suture; base
PART 2. SCAPHOPODA AND GASTROPODA 189
striate, deeply sulcate; umbilicus large, deep, margined with a
carina, smooth within; mouth round.
Length .04. Breadth .10 of an inch.
Remarks.-The longitudinal sulci are quite large on the
upper whorls, but become smaller and closer as they approach
the last whorl, while on the base they again increase. The
striae are very oblique, but are more nearly transverse than
longitudinal. On the last whorl, they form cancellations with
the su 1ci, and are obsolete near the suture as they approach
the mouth. The umbilicus is carinate and scalariform, decreasing
from whorl to whorl in rectangular steps. The periphery
of the last whorl is extremely variable, being in some specimens
almost round, and in others angular and carinate. The mouth
is almost a perfect circle.-H. C. Lea, 1846.
Holotype: Acad. Nat. Sci. Philadelphia 1541.
Type and sole locality: Petersburg, Dinwiddie County,
V a. Yorktown formation.
Apparently the cancellate forms were already established
along the Middle Atlantic coast in the middle
part of Tertiary time.
Genus CIRCULUS Jeffreys
1865. Circulus Jeffreys, British Conchology, vol. 3, p. 315
= .Adeorbis Searles Wood (part) .
Type by monotypy: Delphinula duminyi Requien=Adeorois
striatus Searles Wood, fide Bush, 1897. Recent, in European
waters.
Very small, circular, nearly flat-spired with an exceedingly
wide and open umbilicus.
Operculum circular with about a dozen volutions which wind
spirally and gradually and converge to the centre.-Jeffreys, 1865.
In the typical species the apical surface of the shell is
decorated with a few sharp evenly spaced spiral lirae.
"Circulus" (?supra-nitidus Wood subsp.) orbignyi (Fischer)
Plate 25, figure 33
1857. Adeorbis oroignyi Fischer, Jour. conchyliologie, vol. 6 (2e
ser., vol. 2), pp. 173, 286.
1889. Adeorbis supranitidus var. orbignyi Fischer. Dall, Harvard
Coli. Mus. Comp. Zoology Bull., vol. 18, p. 278
(part).
1892. Adeorbis supranitidus var. oroignyi Fischer. Dall, Wagner
Free Inst. Sci. Trans., vol. 3, pt. 2, p. 344 (part).
Shell minute, subdiscoidal. Whorls inflated medially
and anteriorly, flattened or slightly depressed poste-.
riorly, about 5 in all. Protoconch smooth, of approximately
llf2 turns, differentiated from the conch by its
greater convexity and less regular coiling. First 2
whorls of conch smooth except for microscopically fine ·
incremental striations. Spiral sculpture initiated, as a
rule, on the second whorl of the conch by 3 equal and
equispaced lirations; a fourth lira finer than those in
front of it, but rapidly increasing in prominence, introduced
within· the first quarter turn of the sculptured
conch. Sculpture on posterior and rounded peripheral
portions of body consisting in figured specimen of 8
primary lirations, subequal in size and spacing; secondaries
regularly developed in the umbilical region and
fortuitously on the outer basal surface, particularly toward
the aperture. Incrementals faint but regular, least