Geology and Paleontology of Canal Zone and Adjoining ... - USGS

350 GEOLOGY AND PALEONTOLOGY OF CANAL ZONE
species of Comas. It is fairly slender and has a sharply
angulated shoulder. The spire is of moderate height
and its profile is concave. Late whorls overlap to, or
not quite to, the shoulder angulation. The anal fascicle
is slightly concave and bears (at least on the specimen
of best preservation) weak spiral threads. The largest
of 14 specimens has an almost complete height of 22
mm and a diameter of 13 mm.
This unnamed species is smaller and more slender
than Conus sulculus (Gardner, 1926-47, p. 359, pi. 43,
fig. 3, 1938), of the early Miocene Chipola formation
of Florida.
Occurrence: Upper part of Bohio formation (late
Oligocene), locality 42d. Caimito formation, Gatun
Lake area (late Oligocene), localities 56, 57.
Conus cf. C. planiceps Heilprin
Four lots of poorly preserved small cones from the
La Boca formation suggest a species similar to Conus
planiceps Heilprin (1887, p. 110, pi. 15, figs. 48, 48a),
of the early Miocene Tampa limestone of Florida. The
late whorls form a low, almost flat-topped spire, from
which the earliest preserved whorls (missing on many
of the specimens) abruptly rise. The shoulder is
broadly angulated and the whorls overlap to, or almost
to, the shoulder. The anal fascicle is barely concave
and is sculptured with weak spiral threads. The largest
specimen has an estimated height of 32 mm and a
diameter of 19.5 mm.
C. planiceps reaches a height of 46 mm. As noted by
Mansfield (1937, p. 80), the shoulder of the specimen
from Tampa illustrated by Dall in 1915, p. 37, pi. 6,
figs. 1, 2) is sharply angulated and shows on spire
whorls, but on other specimens in the same lot it is
less sharply angulated and fails to show on spire
whorls. Ball's 1890 illustrations (Dall, 1890-1903, p.
25, pi. 11, figs. 5, 5a, 1890) are poorly drawn or repre­
sent a different species. His brief remarks may be
taken to indicate that the specimen was collected at
Martin Station, Florida, by Willcox. Druid Wilson
suggests that this fossil may be in the collections of
the Philadelphia Academy of Natural Sciences.
A small cone from deposits of middle Miocene age
in the Tehuantepec area of Mexico, recently identified
as C. planiceps (Perrilliat Montoya, 1963, p. 27, pi. 6,
figs. 3, 10), was described as bearing small tubercles
on the shoulder of early spire whorls. Such tubercles
are absent on C. planiceps.
Occurrence: La Boca formation (early Miocene),
localities lOlh, 115a, 115b, 116a.
Conus molis Brown and Pilsbry
Plate 55, figures 8-10
Conus molis Brown and Pilsbry, Acad. Nat. Sci. Phila. Proc.,
v. 63, p. 343, pi. 23, fig. 1, 1911 (Miocene, Canal Zone).
Pilsbry and Brown, Idem, v. 69, p. 32 (list), 1917 (Mio­
cene, Colombia). Olsson, Bull. Am. Paleontology, v. 9,
no. 39, p. 42, pi. 2, figs. 1, 2(1), 1922 (Miocene, Costa
Rica, Panama, Canal Zone). Weisbord, Idem, v. 14, no.
54, p. 56, pi. 6, fig. 1, 1929 (Miocene, Colombia). Ander-
son, Calif. Acad. Sci. Proc., 4th ser., v. 18, no. 4, p. 109,
1929 (Miocene, Colombia).
tConus molis Brown and Pilsbry, Maury, Bull. Am. Paleontol­
ogy, v. 5, no. 29, p. 36, 1917 (Miocene, Dominican Re­
public).
Conus concavitectum Brown and Pilsbry, Acad. Nat. Sci. Phila.
Proc., v. 63, p. 341, pi. 23, figs. 5, 6, 1911 (Miocene, Canal
Zone). Olsson, Bull. Am. Paleontology, v. 9, no. 39, p. 43,
1922. (Miocene, Canal Zone, Panama). Anderson, Calif.
Acad. Sci. Proc., 4th ser., v. 18, no. 4, p. 110, 1929 (Mio­
cene, Colombia).
Conus (Lithoconus) concavitectum Brown and Pilsbry, Coss-
mann, Jour. Conchyliologie, v. 61, p. 43, pi. 4, figs. 3, 4,
1913 (Miocene, Canal Zone).
fConus domingensis Sowerby?, Brown and Pilsbry, Idem, p.
341, 1911 (Miocene, Canal Zone).
Not Conus molis Brown and Pilsbry, Barrios, Colombia Servicio
Geol. Nac., Bol. Geol., v. 6, nos. 1-3 (Informe 1082),
p. 294, pi. 12, fig. 8,1960 (Miocene, Colombia); = C. travoi
Spieker.
Exceptionally large, elongate, moderately wide at
shoulder. Edge of shoulder generally abruptly angu­
lated. Spire of moderate height, its profile concave.
Protoconch consisting of 2i/£ slightly bulging whorls.
Early half of first post-protoconch whorl bearing axial
riblets, angulated shoulder appearing on later half.
Angulated shoulder of first five or six post-protoconch
whorls exposed; first three or four slightly tubercu-
late. Anal fascicle generally concave, bearing spiral
threads. Growth lines of fascicle generally exaggerated
on some whorls. Lower part of body whorl, or entire
whorl, bearing faint spiral sculpture, of decreasing dis­
tinctness upward. Spiral threads on lower part of very
young shells faintly pustulose. Color pattern faintly
showing on some immature shells, consisting of spiral
rows of brownish crude rectangles, much like the pat­
tern of Conus spurius.
Height (practically complete) 160 mm, diameter 90
mm (larger figured specimen).
Type: Princeton University.
Type locality: Gatun Locks excavation, Canal Zone,
middle part of Gatun formation.
Conus molis, based on a mature shell, is given prece­
dence over C. concavitectum, the type of which is im­
mature.
This large species the largest American fossil spe­
cies is found throughout the Gatun formation. A total