TT r\ T r\ n \T
H L G Y;
STRUCTURAL AND SYSTEMATIC,
WITH ILLUSTl^AW^NS ^F THE SPECIES.
BY GEORGE W/TRYON, JR.
CONSF.RVATOU OF TIIK ( '( >N( IIoLOMCA L SKI TIuN T OF Til 1C ACAUJCMY OF NATURAL Si'IKXCKS
OF I'HII A 'iF.U'lllA.
Vol.. \\ II.
NATICTD^E, CALYITIlyEIDyE, TURIUTKLLrD.E, VERlMETr.r)yE ;
(^E( 1 I1LE, EULIMIIXE, Tl'lMU )N I LLI I >.E,
Publislied by tlio Autlior,
ACADEMY OF NATURAL SCIENCES, CCR. IOTH & RACE STS.
\V\i. I'. KM.I.\I:I:. I'IMNTKI:, 7.11 A T:;S.\NS<M ST.. I'll 1 1. ADKI.IMI i \.
MANUAL OF CONCHOLOGY.
Shell subglobular, spiral, or paucispiral, with or without
epidermis, the margin of the aperture entire. Operculum absent,
or present and paucispiral or concentric, corneous or calcareous.
Animal with voluminous foot, often incapable of entirely
withdrawing into its shell; eyes at the base of the tentacles,
often subcutaneous ; shell often partially or entirely covered
by the mantle. Dentition 3*1 '3.
The Naticidae have been monographed by
Reeve, Conch. Iconica : Na'tica, 143 sp., 1855. Sigaretus, 20
sp., 1864. Yanikoro, 24 sp., 1875.
Philippi, in Kiister's Conchylien Cabinet, 1852 : Natica, 190
Weinkauff, in Kiister : Sigaretus, 37 species, 1883.
Sowerby, in Thesaurus Conclryliorum : Sigaretus, 28 sp., 1882.
Yanikoro, 24 sp., 1884. Natica, 144 sp., 1883.
Recluz, in Chenu's Illustrations Conchy liologiques, etc.
The present work admits about 225 recent species belonging
to the family ; many of those recognized by previous mono-
graphers being considered synonyms : besides these there are
many unfigured and undetermined forms.
Subfamily I. Naticinde.
Shell turbinate, subglobose or auriform, the spire usually
short; aperture entire, without canal or sinus, the outer lip
sharp, not reflected or margined, the columellar lip callous, more
or less reflected over the umbilicus. Operculum calcareous or
corneous, paucispiral (PI. 1, figs. 12-14).
Animal with small tentacles, which are lanceolate, wide apart,
connected by a veil ; eyes absent, or placed under the skin,
behind the tentacles ; foot much produced in front, where it is
furnished with a fold (propodium) covering the head and anterior
margin of the shell ; operculigerous lobe very ample, partially
enveloping the shell ; mantle enclosed. Jaws corneous, waved or
tessellated, subtrigonal (PL 1, fig. 3). Central tooth of the
radula trapezoidal, generally tricuspidate, lateral teeth with a
central large and smaller cusps, inner marginals simple or bifid,
outer marginals simple (PI. 1, figs. 4-6).
The animals of Naticidrc, characterized by the cephalic disk
forming the propodium, are completely retractile within the
shell in the typical Natica, but not retractile in Sigaretus and
Mamilla. In some species of Neverita, the posterior margin of
the propodium forms on the left side a sort of fleshy siphon ; the
operculigerous lobe, which encircles the shell sometimes has a
sinus on the right side, probably for the introduction of water
into the branchial cavity.
The Natica (PL 7, fig. 43) is an active animal, carnivorous and
very predaceous, living in sandy places, where it hides under the
surface and burrows for bivalves. These it pierces with its
tongue, boring a round hole, generally near the beaks, where
the shell of the victim is thinnest. The eyes, hidden by the
propodium, and subcutaneous, are generally not perceptible, but
can be distinguished in the group Amaura.
The Nidus (PL 7, figs. 44, 45) is unlike that of any other
mollusk in form and composition, being built up largely of
the sand of the sea-bottom, agglutinated into a strap, forming
part of a circle, and provided on one side with a constriction or
rim ; the walls contain the eggs, arranged in quincunx order.
Subfamily II. Lamellar iinse.
Shell thin, sigaretiform, more or less internal, generally pauci-
spiral, sometimes reduced to a non-spiral auriform lamina; spire
short, few-whorled, lateral; aperture oval, entire, large. No
The animal (PL 1, figs. 18, 19) has not the cephalic disk of
Xatica. The mantle gradually grows over the shell until the
hitter becomes, in some of the rcnor:i, completely internal ; eyes
on prominences at the base of the tentacles. Dentition, PI. 1,
The Lamellariinte are carnivorous, living upon Hydrozoa,
Alcyonaria and compound Ascidise. The eggs are deposited in
the midst of colonies of the latter. The tirst embryonic shell
is nautiloid, with spiral ridges ; the second is more simple,
resembling a Carinaria; these shells are united at their margins
by a thin membrane. The pelagic larval forms have received
the names of Brownia, Echinospira, Calcarella and JasoniUa.
See Manual, ii, t. 8, f. 103-105 ; Structural and Syst. Conch., i,
130, t. 20, f. 51.
Subfamily III. Vanikoridse.
Shell external, white, with sometimes a velvety epidermis,
usually striated, costate or decussated ; umbilicated, without a
trace of callus. Opercnlum thin, corneous, non-spiral.
Animal with a long snout, tentacles flattened, much dilated in
the middle, narrow above ; eyes sessile at their external base ;
mantle margin simple ; foot profoundly bipartite, a narrow,
truncated, elongated propodium and a larger, rounded or sub-
quadrangular, operculigerous metapodiuin ; a large epipodial
veil on each side of the foot^; branchia a single row of triangular
leaflets, partly free. Jaws flattened; radula short and wide,
having, according to Gray, two series of teeth (?).
Synopsis of Genera.
Genus NATICA, Adanson, 115?.
Shell oval globular, porcellanous, solid, generally smooth,
covered by a fine epidermis, which is transparent, and generally
not very persistent; umbilicated, or umbilicus more or less
tilled with callus ; aperture semilunar, vertical, the outer lip
simple. Operculum large, semilunar, paucispiral, corneous or
Animal with large cephalic lobe, truncated in front, subquad-
Subgenus NATICA (sensu stricto).
Shell smooth, solid, brightly colored in bands, spots, stripes,
etc. Operculum calcareous (PI. 1, figs. 12, 13). N. canrena,
The species are numerous; mostly inhabitants of warm sens,
in all quarters of the globe. The genus first appeared in the
Jurassic formation. The fossil forms are remarkable for the
persistence of their colors. Nacca, Risso, is a synonym.
Section STIGMAULAX, Morch, 1852.
Whorls cancellated or grooved. N. cancellata, Lam.
Subgenns NEVERITA, Risso, 1826.
Shell large, depressed orbicular, spire conical or flattened ;
umbilicus open, or partly filled by a tongue-shaped callous process
(funiculum) of the columella. Operculum corneous. Dentition,
PI. 1, fig. 0. N. duplicate, , Say.
The shell of Neverita is usually larger sized, sombre colored,
and not so solid as that of Natica. The group inhabits mostly
Section NEVERITA (typical).
Umbilicus partly filled by a tongue-shaped callous process of
Section LUNATIA, Gray, 1847.
Shell subglobose, large, umbilicus open, without funiculum.
Almost insensiblj r connects with Neverita. Operculum, PI. 1,
fig. 14. N. heroSj Say.
Section PAYREAUDAUTIA, Bucquoy, Dautzenberg and Dollfus,
Umbilicus furnished with two funicular plications; shell small,
variegated. N. intricata, Donovan.
Appears to connect with the typical group which it resembles
in coloration, but distinguished by its umbilicus and operculum.
Section MAMMA, Klein, 17f>3.
Shell oval or suboval, solid, smooth, usually unicolored, white
or yellowish ; aperture semilunar, inner lip oblique, callous, the
callus extending into and more or less complete!}' filling the
umbilicus. N. uber, Yal.
Polinices, Montf., 1810, Mamillaria, Swains.. 1840, Nali<-uui,
Guildintr, 1884, and Naticella, Guilding, 1840, arc- synonyms.
Section CEP ATI A, Gray, 1840.
Shell rotelliform ; umbilicus closed by a large callosity, a
pliciform lamella on the upper part of the columelhir lip. Fossil
only. N. cepacea, Lam. Eocene.
Velainia, Munier-Chalmas, 1884, is a synonym.
Section MAMILLA, Schum., 1817.
Shell oval conic, rather thin, the whorls oblique, rapidly
enlarging ; white or fasciated with brown ; mouth oblong, inner
lip narrow, reflected, usually brown or blackish; umbilicus not
funiculated. A 7 , maura, Lam.
The synonyms are Naticaria, Swainson, 1840, and Btima
(Chemn.), H. and A. Adams, 1853.
Subgenus AMPULLINA, Lam. jfate Def ranee, 1821.
Umbilicus without funiculum, sometimes open, sometimes
closed by a callosity ; columellar margin usually convex, the
umbilical region limited by a spiral ridge.
Globularia, Swainson, is a synonym.
Only one living species belongs in this group ; the rest are
Section AMPULLINA (sensu stricto).
Spire short, aperture large. N. sigaretina, Lam. Eocene,
Paris (Struct, and Syst. Conch., t. Ixiv, f. 66).
Ampullinopsis, Conrad, may perhaps be placed here. Globu-
laria, Swains., is also a synonym.
Section AMAURELLINA, Bayle, 1885.
Spire scalariform, elongated, sharp ; umbilicus with u narrow
false funiculum. N. spirata, Lam.
Section MEGATYLOTUS, Fischer, 1885.
Callosity of the umbilical region very large, limited by a
semicircular groove, distant from the columella. N. rrassatina,
Lam. Lower Miocene.
Section CERNINA, Gray, 1840.
Subglobose, polished, bright colored ; -aperture large; umbili-
cal region entirely covered by a convex callosity, not limited by
a groove ; columellar margin convex. N. fluctuata, Sowb., the
sole living species of this subgenus.
Anomphala, Jonas, is a synonym.
Subgenus EUSPIRA, Agassiz, 1837.
Spire more or less elevated, suture canaliculated ; whorls few,
angulated or carinated ; umbilical fissure little marked or hidden.
N. canaliculate,, Morris and Lye., Oolite, England. (Struct, and
Syst. Conch., t. Ixiv, f. 84).
Subgenus A MAURA, Moller, 1842.
Shell oval, smooth, thin, imperforate, covered by an epidermis ;
aperture oblong, columella short, simple.
Animal with small, compact foot, the right lobe profoundly
sinuated ; eyes subcutaneous, but visible.
A boreal group, commencing with Jurassic fossils, and con-
taining a few living species. N. Candida, Moller.
Section ACRYBTA, H. and A. Adams, 1853.
Shell globular, spire very short; columellar margin incurved,
columella twisted ; lip fragile. N.flava, Gould.
Bulbus, Brown, 1839, is a synonym.
Section AMAUROPSIS, Morch, 1851.
Suture canaliculated. N. canaliculata, Gould.
Section PSEUDAMAURA, Fischer, 1885.
Shell more solid, longitudinally ribbed. N. bulbiformis, Sowb.,
Section PTYCHOSTOMA, Laube, 1866.
Shell imperforate, oval ; spire large, elevated, sharp ; aperture
oval, angular posteriorly ; columella straight ; the margin arcu-
ated ; lip sinuated near the suture ; growth lines sinuous. N.
Pleurotomoides, Wissman. Triassic.
? Subgenus AMAURELLA, A. Adams, 1867.
Shell small, imperforate, white, shining, apex submamillary,
aperture acuminately ovate ; lip arcuate, simple, a little thickened.
It is very doubtful where in the system these little shells
should be placed. The tj r pe species was originally described as
a Macrocheilus, but it was subsequently said to have greater
affinities with Amaura.
Subgenus NATICOPSIS, M'Coy.
Shell imperforate ; inner lip very thick, spreading. Operculum
shelly. N. Phillipsii, M'Coy. Carboniferous, Gt. Brit. (Struct,
and Syst. Conch., t. Ixiv, f. 67).
Neritomopsis, Waagen, 1880, is a synonym.
Section ISONEMA, Meek. /. humilis, Meek. Devonian, Ohio
(S. and S. Conch., t. Ixiv, f. 71).
Section TRACIIYDOMIA, Moek and Worthen, 1866.
Surface covered by small regularly disposed tubercles.
N. nodosa, M. and W. Carboniferous, Illinois.
Subgenus GYRODES, Conrad, 1860.
Shell depressed globose ; aperture generally angular or nar-
rowly rounded below ; inner lip thin ; umbilicus wide, deep,
without callosity, bounded by a revolving carina which is some-
times crenate, with occasionally a second small revolving ridge
within ; whorls shouldered above, the angle generally wrinkled
Cretaceous, United States, India. N. alveata, Conr. (S. and S.
Conch., t. Ixiv, f. 70).
Subgenus TYCHONIA, de Koninck, 1881.
Shell somewhat depressed, globose, smooth; spire short,
obtuse, suture linear ; last whorl very large, depressed at the
base ; aperture semilunar ; lip thin ; columella thickened by a
callosity which is limited by a shallow oblique groove ; no
N. Omaliana, de Koninck. Carboniferous, Belgium.
? Subgenus PLATYOSTOMA, Conrad.
Shell subglobose ; spire short ; aperture very large, suborbicu-
lar, dilated ; labrum joining the body-whorl at right-angles to the
axis of the shell.
P. Niagarensis, Hall. Niagara group, New York (S. and S.
Conch., t. Ixiv, f. 14).
Section STROPHOSTYLUS, Hall.
Shell subglobose, spire small, body-whorl large, ventricose ;
outer lip thin, sometimes slightly expanded ; columella twisted
or spirally grooved within, not reflected ; umbilicus none. P.
subobtusa, Hall. Lower Helderberg, N. York (S. and S. Conch.,
t. Ixiv, f. 75).
Differs in its twisted or grooved columella.
Section ORIOSTOMA, Munier-Chalmas, 1876.
Umbilicus moderate, circumscribed by a carina ; whorls some-
times partially free. P. Barrandei, Mun.-Chalm. Devonian.
The relations of this group with Natica are somewhat obscure,
as are also those of the typical form with those designated here
as sections. As in many other cases with the older fossil forms
we can only be guided by rather remote general resemblances.
Tylostoma, Sharpe, is considered a member of the group by
some conchologists ; I have placed it in Tornatellidiu (See Struct,
and Syst. Conch., ii, 357).
Genus RUMELLA, Bourguignat, 1885.
Shell small, obliquely oval, polished, spire short, of few whorls ;
last whorl with a large umbilical depression, limited by a basal
angle, and covered by a strong rounded callus ; lip simple. Opcr-
Lake Tanganika, Central Africa.
The species are said to resemble the group Mamilla in minia-
ture; their position cannot be positively ascertained until we
become acquainted with the animal and operculum.
Genus SIGARETUS, Lamarck, 1799.
Shell depressed ear-shaped, with minute spire and very large
aperture, externally with revolving striae; color usually white,
sometimes invested with a thin corneous epidermis. Operculum
minute, horny, paucispiral (PI. 1, fig. 15).
Animal with large mantle partly or entirely covering the shell
into which it is not able to withdraw entirely. Dentition.
Central tooth of the radula shorter than the lateral cusps (PI. 1,
Sigaretus inhabits warm seas, on muddy sand-flats ; it is slug-
gish and very timid, moving slowly; when crawling they con-
stantly explore the surrounding surface with the produced fore-
lobe of the foot, which is also used in burrowing.
Living species are rather numerous; fossil, it commences in
the Cretaceous. Catinu* (Klein, 1753), H. and A. Adams;
Lnpia, Conrad ; Stomatia, Hill ; Cryptostoma, Blainv., 1818, and
Raynevallia, Ponzi, are synonyms.
Section SIGARETUS (.se/zsw. stricto).
Shell depressed orbicular, convex above, mouth rounded ;
umbilicus none or covered by a reflection of the inner lip ; spire
Section EUNATICINA, Fischer. 1885.
Shell umbilicated, oval oblong, thin, ventricose ; spire sharp;
inner lip straight, thin anteriorly, with a median callus. N.
It is Naticina, Gray, 1840 (not Guilding, 1834). Lacunaria,
Conrad, was referred here by me in Structural and Syst. Conch. ;
its species having been described as Naticse ; it is now placed in
Section AMPLOSTOMA, Stoliczka, 1868.
Subovate, thin, spire short ; whorls few, the last large, ventri-
cose, produced in front, widely excavated at base ; aperture
elongately ovate, subangulated, pillar lip smooth, outer lip
dilated and expanded at the margin ; surface nearly smooth.
S. auriformis, Stol., Cretaceous, So. India (S. <fc S. Conch., t.
Ixiv, f. 85).
The characters are exceedingly close to those of the last
section. Lysis, Gabb., 1864, which I consider a member of the
subfamily Purpurinre, of Muricid;v, has been referred to this
neighborhood by Dr. Fischer.
Subfamily II. LartiellariiUK.
Genus LAMELLARIA, Montagu, 1815.
Shell internal, ear-shaped, thin, pellucid ; spire lateral, very
small; aperture large, patulous, both lips regularly arcuated;
axis imperforate. No operculum.
Animal much larger than the shell, which is entirely concealed
beneath the dorsal shield ; shield thick, verrucose, notched in
front; foot elongated, truncated in front, acuminated behind;
eyes at the outer bases of the tentacles. Dentition 1*1-1, the
central tooth subtrigonal, with the free margin denticulated and
base incurved ; laterals large, the summit lanceolate, the margins
denticulate, no marginals (PL 1, fig. 9).
There are a few living species, and two species in the Miocene.
Interesting particulars of the habits of Lamellaria will be found
in Structural and Systematic Concholog}', ii, 209.
The synonymy includes Marsenia, Leach, 1847 ; Coriocella,
Blainv., 1824; Chelinotus, Swains., 1840 ; Cryptocella, H. & A.
Adams, 1853; Ermvea, Gray, 1857; Cryptothyra, Menke, 1830.
Coriocella and Cryptocella have been considered subgenera, but
have no important characters ; the former was founded upon an
individual accidentally deprived of its shell. The fry, also,
have received several generic names (p. 5).
Subgenus MARSENINA, Gray, 1850.
Shell auriform, similar to Lamellaria.
Animal (PI. 1, fig. 20) with shield only partially covering the
shell, open in the middle, the anterior margin deeply incised a
little to the left of the middle, and again incised at the middle
of the right margin. Dentition, PI. 1, fig. 10. Boreal Seas.
L. prodita, Loven. Goloboccphalus, Sars, is a synonym.
Genus ONCIDIOPSIS (Beck), Bergh, 1853.
Shell internal, membranous, flexible, slipper-shaped, not spiral,
oblong, obtuse at the extremities.
Animal (PI. 1, fig. 21) completely enveloping the shell ; dorsal
shield verrucose, thick, margin entire ; foot elongated, lanceo-
late, exceeding the shield at either extremity ; tentacles cylin-
drical, with eyes at their exterior bases. Dentition as in Velutina
(PI. 1, fig. 11). Boreal Seas. 0. glacialis, Sars.
? Genus CALEDONIELLA, Souverbie, 1869.
Shell heliciform, imperforate, oval, orbicular, thin, invested by
a thin epidermis which extends beyond the lip ; spire much
depressed, sublateral ; whorls few, rapidly increasing ; aperture
oblique, rather large, the extremities of the simple lip united by
a callus extending widely upon the whorl. Animal unknown.
C. Montrouzieri, Souverb. New Caledonia.
Genus VELUTINA, Fleming, 1822.
Shell thin, mostly external, calcareous, auriform, paucispiral,
invested by a velvety epidermis ; spire lateral, suture well im-
pressed; aperture large, rounded, the lip thin, the columellar
lip a little reflected. No operculum.
Animal with large oblong foot; margin of mantle developed,
ami more or less reflected over the edge of the shell; hc:ul
broad ; tentacles subulate, blunt, far apart, with eyes on prom-
inences at their outer bases.
Dentition, 2*l*l'l-2, the central tooth subquadrangular, multi-
cuspid, the central cusps very long and sharp; lateral teeth
multicuspid, marginals narrow, with a few obsolete denticles on
the margin (PI. 1, fig. 8).
The Velutinas resemble the pulmoniferous genus Otina, but
are strictly marine. Sometimes they are met with far out at
sea, but usually live among stones near low-tide. Boreal. V.
? Catinella, Stache, is a synonym.
Section LIMNERIA, H. and A. Adams, 1853.
Spire more elevated, peristome not continuous, columella
subcanaliculate. F. undata, Brown.
Morvillia, Gray, 1857, is a synonym.
Section VELUTELLA, Gray, 1847.
Shell in most part covered by the mantle, very thin, flexible,
with short spire ; peristome continuous, thickened. V. Jlexilis,
Section LEPTONOTIS, Conrad, 1866.
Margin of the aperture remarkably expanded, surpassing tho
spire. V. expansa, Whitfield. Eocene. Alabama.
The shell is minute, and may be embryonic.
SC^EVOGYRA, Whitfield, 1817. Struc. and Syst. Conch., iii, 350.
LYOSOMA, White, 1883. Struc. and Syst. Conch., iii, 350.
These two fossil groups, of doubtful relationships, may
possibly be members of the Naticidn-.
Subfamily III. Vanikoridde.
Genus VANIKORO, Quoy and Gaimard, 1832.
Shell subglobose, external, white, with a velvety epidermis,
surface striate, costate or decussate, umbilicated, without a trace
of callus in the umbilicus ; spire not produced; aperture semi-
lunar, outer lip simple.
Animal described in the subfamil}'. Operculum thin, corneous,
with apical nucleus, not spiral (PL 1, figs. 16, 17).
A few species are found about corals in warm seas; fossil,
commences with secondary strata.
About equally well-known under the later and perhaps more
acceptable name of Narica, Recluz, 1841. Leucotis, Swainson,
1840, and Merria, Gray, 1842, are also synonyms.
Section YANIKOROPSIS, Meek, 1876.
Shell subglobose, thick, body-whorl large, spire low ; imper-
1 4 NATTCA.
foratc ; outer lip simple, beveled, inner lip closely folded upon and
adhering to the columella and body-whorl, very little thickened,
smooth ; surface with distinct revolving lines and furrows,
developing on the body-whorl strong oblique grooves parallel to
the growth lines. F. Tuomeyana, Meek and Worthen. Creta-
ceous ; Upper Missouri River (S. and S. Conch., t. Ixiv, f. 87).
Section NATICODON, Ryckholt.
Shell like Vanikoro, but inner lip usually thickened, and
always provided with some kind of a tooth , columella either
slightly hollowed out or solid ; surface smooth, or ornamented
with various spiral or transverse striae. F. spirata, Sowb.
Carboniferous, Europe (S. and S. Conch., t. Ixiv, f. 76).
This group forms a connecting-link between Vanikoro and Neri-
topsis ; the former having the columellar lip smooth, the latter
insinuated in the middle, or provided with two strong teeth,
while Naticodon has only one tooth ; as regards the thickness of
the shell, this transition seems equally to hold good.
Section NATIRIA, de Koninck, 1881.
Shell globose, spire short, suture profound, axis perforated ;
surface longitudinal!}' plicate, with intermediate parallel striae,
and slight spiral striae ; columellar margin slightly thickened ;
aperture nearly circular, peristome continuous. Carboniferous-
Trias. F. lirata, Phillips.
Genus NATICA, Adanson, 1757.
Subgenus NATICA (sensu stricto).
N. MILLEPUNCTATA, Lam. PL 2, figs. 22, 23, 24, 25.
Yellowish white, closely painted with small light chestnut
spots, umbilical region and interior of aperture light brown ;
umbilicus with a central entering ridge. Length, 1-5-2 inches.
Linnaeus classed this among the varieties of his N. canrena.
It is a variable species in its color markings, thus acquiring
several synonyms. Among those of the typical color-variety are
N. punctata, Karsten, and N. stercus-muscarum, Gmel. (juvenile).
Monterosato has named a var. minor.
Var. MACULATA, Desh. PL 2, fig. 24.
The spots larger, less sharply defined, often interruptedly con-
fluent, with three interrupted bands of larger spots or macula-
Appears to connect closely with the type form, but has been
separated as a distinct species of late years by several concholo-
gists on account of differences in the lingual dentition. I retain
the name by which the species is well known instead of the prior
one of N. hebrtea, Martyn which has scarcely obtained currency.
Other synonyms are N. trifasciata (Recluz), Adams ; N. aspersa,
Menke ; N. cruentata, Payr.
Monterosato has named as color-varieties, fusca, immaculata,
and rarimaculata. The latter appears to me to connect with the
Var. SANGUINOLENTA, Brusina. PI. 2, fig. 25.
The punctations coalescing into undulating longitudinal flam-
N. PULMINEA, Gmelin. PL 2, figs 26, 27.
Shell solid, somewhat tumid and plicately striated next the
suture ; umbilicated, but the umbilicus partly covered by an
overgrowing callous deposit on the upper part of the columellar
lip, which finally becomes very thick; whitish, with longitudinal