Conus dodona
(Gardner, 1937)
The distribution of the cones in the
Chipola, Oak Grove, and Shoal River faunas is remarkably local.
Of the 14 species
represented not one occurs in all the faunas, and only a single one is common
to any two. Though clearly related to the mid-American cones none of the 14 has
been recognized outside of the Alum Bluff of Florida.
The Chipola fauna is
characterized by C. isomitratus and the closely related C. sulculus,
with the somewhat less abundant C. demiurgus of the larger, stouter type
and, among the more slender races, C. chipolanus Dall, with a meager
representation of the Oak Grove species C. corrugatus.
The Oak Grove fauna
is dominated by Conus dodona, a form that suggests Conus proteus
Hwass of the late Tertiary and Recent seas, and the smaller Conus corrugatus.
The Shoal River
fauna is characterized by its isolated cone fauna of 3 species and 1
subspecies, none of which occur outside the Shoal River formation and two of
which, C. waltonensis and its subspecies anodosus, greatly exceed
in abundance any other member of the cones within the Alum Bluff group. The
Chipola and Oak Grove faunas are obviously much more closely related to each
other than to the Shoal River. The Shoal River fauna is the most peculiar of
the three, and through its dominant species, so extraordinarily prolific in
Walton County, is related to other mid-Miocene faunas of the mid-American
province. The character of the cones as a whole indicates throughout the Alum
Bluff warm and very shallow waters (1).
Diagnosis (1):
Shell
rather large and heavy. Spire not more than one-fifth of the entire altitude in
the adult forms. Whorls approximately 9, including the 2 or 3 nuclear coils,
which are small, of nearly the same size, and laterally compressed and form a
sharp and prominent little knob in the center of the low spire. Earlier whorls
of conch flattened upon the shoulder; later whorls concave, the sutures very
closely appressed and the peripheral margin slightly elevated. Incremental
sculpture well developed in the concave area between the periphery and the
suture. Spiral sculpture restricted to a dozen or more unequal and
inequispaced, irregular oblique spirals upon the anterior third of the body.
Aperture of average width. Outer lip thin, sharp, deeply emarginate at the
shoulder. Inner lip smooth, reinforced at the anterior canal. Anterior canal
wide, flaring slightly, obliquely truncated. Dimensions: Maximum height, 33.8
millimeters; length of aperture, 29.0 millimeters; maximum diameter, 19.0
millimeters. Holotype: U. S. Nat. Mus. No. 349858.
Type
locality: No. 2646, Oak Grove, Yellow River, Okaloosa County, Fla
This species suggests a low-spired Conus proteus Hwass (pl.
XLIII, fig. 5) with a scooped-out shoulder.
Conus demiurgus Dall attains a larger size, has a lower spire, with a
flattened rather than a concave shoulder even in the later whorls, and is more
attenuated anteriorly.
Conus isomitratus Dall is smaller and stouter as a rule and does not
reveal the periphery of the whorls of the spire.
Conus fusoides brachys Pilsbry from the Gurabo formation of the
Dominican Republic is more angular with the suture, particularly on the early
whorls, following more closely the periphery.
Conus dodona is the largest cone reported from the Oak Grove. It
is abundant at certain localities, notably on the Yellow River, half a mile
east of Oak Grove, but it has not been found at any other horizon of the Alum
Bluff.
Occurrence: Oak Grove sand, localities 2646 a, 5633P, 7054 P .
|
|
Conus dodona
Tav.
XLIII fig. 4 mm.
33,8 x 19,0 |
Bibliografia
Consultata
·
(1) - Gardner, J., 1937. The
Molluscan Fauna of the Alum Bluff Group of Florida. U.S. Geological Survey
Professional Paper, 142-F
·