Conus (Lithoconus)  sauridens (Conrad, 1833)  

Descrizione e caratteristiche:

Conchiglia liscia ad eccezione della base, che è striata obliquamente; la superficie delle spire è appiattita e rigata; l'apice è appuntito, l'apertura è sottile e la spalla è angolata.

Il guscio è sottile e fragile, liscio con striature spirali impresse alla base; il profilo dell'ultimo giro è lineare, la spira è corta, leggermente concava, con 5/6 strie spirali e linee di accrescimento che formato un reticolo; la sutura è carenata; la spalla è angolata; la columella è piegata alla base ⁽²⁾.

E’ interessante il confronto del Conus sauridens con il Conus chiraensis del Perù.

v. Conus mutilatus (Alabama)

Conus (Lithoconus) subsauridens (Conrad, 1865)

Descrizione e caratteristiche:

Conchiglia allungata e conica in modo acuto, ha fianchi rettilinei, leggermente incurvati verso la sommità dell’ultimo giro; la sommità e le spire sono carenate con un angolo acuto. Differisce dal Conus alveatus per la forma; la parte inferiore ha linee più fini, più uguali e più numerose Pl. 11 fig. 9 ⁽³⁾.

Il Conus subsauridens non sembra essere differente dal Conus sauridens ⁽¹⁾.

Conus (Lithoconus)  claibornensis (Isaac Lea, 1833)

Description. A small cone, for which I had proposed this name, was found in the sand, and by accident was mislaid, before the description and figure were made. It was about one quarter of an inch long, flattened on the sides, carinate above, and canaliculate on the superior part of the whorls; the spire was rather low and pointed. It is to be regretted that any accident should have happened to it, as it is the only specimen of a cone found at this locality, to my knowledge ⁽⁶⁾.

Il Conus claibornensis è un sinonimo del C. sauridens: l’esemplare ANSP 5931 è andato perso prima di essere raffigurato e descritto dettagliatamente. Conrad l’ha rapportato al Conus sauridens.

Conus (Leptoconus) smithvillensis (Harris, 1895)

Specific characterization. —General form as figured; whorls about 12; smaller spiral whorls costate or crenulate; penultimate whorl smooth; body whorl smooth, except about 12 revolving lines at base. This species bears much resemblance to the figure given in Proce. Ac. Nat. Sci’ Phila., 1879, pl. 13, fig. 8, of “ Conus” pulcherrimus Heilp., but upon examining the type of this species now in the Amer. Mus. Nat. Hist., N. Y. City, it was found to be, as already stated by Meyer, a Pleurotomoid shell. C. parvus of H. C. Lea is evidently the young of C. sauridens ⁽⁷⁾n.

 

1895. Conus smithvillensis HARRIS, Acad. Nat. Sci. Philadelphia, Proc., p. 55, pl. 4, fig. 2.

1937. Conus (Lithoconus) smithvillensis Harris. PALMER, Bull. Am. Paleontology, vol. 7, no. 32, p. 464, pl. 73, figs. 17, 21.

"General form as figured; whorls about 12; smaller spiral whorls costate or crenulate; penultimate whorl smooth; body whorl smooth, except about 12 revolving lines at base... ⁽⁷⁾

"Locality. Smithville, Bastrop Co., Тех ⁽⁷⁾.

"Type. Texas State Museum." Harris, 1895 ⁽⁷⁾.

Conus smithvillensis differs from C. santander in the notably higher spire and more slender and more attenuated body. A peripheral noding is evident on the early whorls, and there is in addition a noding of the 3 or 4 moderately strong lirations on the shoulder. In our collections, none of the examples of C. smithvillensis exceed 40 millimeters in height, and the species occupies consistently a slightly lower horizon in the lower Claiborne than that in which Conus santander is found ⁽⁷⁾.

A smallish, high-spired species in the lower Laredo at U.S.G.S. sta. 13596 (H-15) near China, Carlos Cantú, Nuevo León, is commonly represented, but none of the material is well preserved. How-ever, the small size, high spire, and the few remnants of a noded sculpture pattern indicate the Smithville form. Nothing of the sort has been found in the higher horizons ⁽⁷⁾.

Distribuzione: Mississippi, Texas, Messico ⁽⁷⁾.

Conus (Leptoconus) haighti (Gardner, 1945)

Shell rather large and heavy for the subgenus, probably as many as 15 whorls in the fully adult. Early whorls coiled in a plane that is nearly horizontal, the later whorls terraced so that in the holotype the aperture is about four fifths of the length of the shell. Sides of body converging at an angle between 35° and 40°. Protoconch not preserved in any of the available material. Earliest conchal turns high, increasing slowly in diameter and forming with the protoconch a small knob in the middle of the adolescent whorls, which are coiled in nearly a single plane. Change in the plane of coiling rather abrupt, the suture dropping in front of the narrow shoulder and giving to the spire a turreted contour. Spiral sculpture confined to a few rather feeble and irregular lirations on the shoulder, least feeble directly behind the slightly raised outer rim. Aperture oblique to the axis, narrow; the margins parallel as far as the anterior fasciole. Growth lines strongly retractive on the shoulder, bending sharply directly behind the periphery; in front of the periphery, strongly protractive. Outer lip thin, sharp, widely flaring. Inner wall apparently free from wash. Characters of anterior extremity obscured by the matrix. Anterior fasciole bulging slightly and corrugated by the heavy growth lines. No visible inner pad of callus, such as that developed in Conus santander; possibly concealed by matrix.

DIMENSIONS OF HOLOTYPE: Height, 60 millimeters; greatest diameter, 31.5 millimeters.

HOLOTYPE: U. S. Nat. Mus. 495182; incomplete paratype, U. S. Nat. Mus. 495183; figured specimen, U. S. Nat. Mus. 496037. Middle part of the Laredo formation.

TYPE LOCALITIES: Holotype, U.S.G.S. sta. 13168, Arroyo Veleño, below highway bridge on Zapata-Roma road, Zapata County, Texas; incomplete paratype, U.S.G.S. sta. 13984 (H-6); figured specimen, U.S.G.S. sta. 13565 (H-12).

Conus haighti when adult and fairly well preserved is readily separable from the earlier Conus santander. The spire is higher and more unevenly coiled. In the adolescent, the suture follows the almost horizontal shoulder so that the visible portion forms a disk with a central knob of the nuclear and earliest postnuclear whorls, and together they top the later turreted whorls like a coolie hat. The greater number of the individuals are known only from the worn posterior half of the shell, and the characters of the anterior extremity are to a certain degree conjectural. The paratype is typical of the common state of preservation. Conus haighti seems to occupy a horizon slightly higher than that in which Conus santander is abundant.

The species is named in honor of Harold W. Haight to whom we owe many of our most valuable collections.

DISTRIBUTION: Laredo formation: middle Laredo, U.S.G.S. sta. 13984 (H-6); U.S.G.S. sta. 13800 (H-9); U.S.G.S. sta. 13685 (H-9); ?U.S.G.S. sta. 13567 (H-11); U.S.G.S. sta. 13565 (H-12); U.S.G.S. sta. 13569 (H-12); U.S.G.S. sta. 13570 (H-12); U.S.G.S. sta. 13590 (I-13); U.S.G.S. sta. 13594 (H-13); U.S.G.S. sta. 13591 (H-13); U.S.G.S. sta. 13555 (H-14); U.S.G.S. sta. 13547 (I-14); U.S.G.S. sta. 13554 (I-14); U.S.G.S. sta. 13553 (H-15); U.S.G.S. sta. 13551 (H-15); U.S.G.S. sta. 13643 (M-25).

Conus (Leptoconus) santander (Gardner, 1945)

1931. Conus sauridens Conrad. RENICK AND STENZEL, Univ. Texas Bull. 3101, p. 100, pl. 6, fig. 6. Not Conus sauridens CONRAD, Fossil shells of the Tertiary formations of North America, p. 33, 1833.

1937. Conus (Lithoconus) sauridens Conrad (part). PALMER, Bull. Am. Paleontology, vol. 7, no. 32, pp. 458-459.

Shell rather heavy, porcellaneous, the spire low and the sides converging at an angle of 45° or less. Nuclear turns small, high, smooth, and polished, 3 or 2 and a fraction in number. The 4 or 5 succeed-ing turns closely noded, the nodes on the earliest postnuclear turns medial but pushed forward with the development of the shoulder and gradually dying out. Suture following close on the shoulder on the adolescent whorls but inclined to drop farther and farther forward in the adult and gerontic forms. Spiral sculpture restricted to half a dozen or fewer not very regular spirals on the shoulder and a faint irregular lineation toward the base of the body. Aperture as wide as the shoulder, oblique to the axis of the shell, the margins parallel as far as the anterior fasciole. Anal fasciolar notch shallow as indicated by the feebly arcuate growth lines. Outer lip thin, sharp, flaring widely,

Le pareti sono nettamente più diritte rispetto al Conus sauridens.

Conus jacksonensis (Meyer, 1885)

Per Meyer, il Conus jacksonensis è simile al Conus protractus, ma le spire presentano rigature spiraliformi⁽⁸⁾.

Meyer named a new cone from the Jackson, C. jacksonensis, without adequately describing or figuring it. Dr. Charles Berry, formerly of the Geology Department, the Johns Hopkins University, kindly loaned the type of C. jacksonoisis, and it is figured herein. The specimen, as it exists today, consists of the apical whorls. They appear to be the characteristic type of the C. sauridens stock and probably are therefore the apical whorls of C. tortilis ⁽⁹⁾.

Jackson, Alabama

Bibliografia Consultata

• (1)  - Dall (1895) “Fossils from Southern United States”, Proceeding of The United States National Museum, Volume XVIII, Smithsonian Institution, Washington

• (2) - Conrad (1835), “FOSSIL SHELLS OF THE TERTIARY FORMATION OF NORTH AMERICA

• (3) – Conrad (1865), American Journal of Conchology Vol. 1 Part 2

• (4) - The Molluscan Macrofauna of the Reklaw Formation, Marquez Member (Eocene: Lower Claibornian), in Texas.Bulletins of American Paleontology, 111 (352

• (5) – Brown & Pilsbry (1911) – “Fauna of the Gatun Formation”

• (6) - Contributions to Geology, 1833

• (7) - NEW AND OTHERWISE INTERESTING TERTIARY MOLLUSCA FROM TEXAS. BY GILBERT D. HARRIS,

• (8) - Meyer (1885) “Species in the Southern Old-Tertiary”, The American Journal of Science – Third series – Vol. XXIX

• (9) - THE MOLLUSCA OF THE JACKSON EOCENE OF THE MISSISSIPPI EMBAYMENT (SABINE KIVEK TO THE ALABAMA RIVER) By Gilbert D. Harris and Katherine VanWinkle Palmer

• (10) - Hendricks, Portell (2008) “ Late Eocene Conus (Neogastropoda: Conidae) from Florida, USA“