Conus safaedensis
(Eames, 1952)
Material.
Eocene of Domanda (1 paratype, Reg. No. G. 68403). Lower Chocolate Clays east of Safaed, south of Tobah, Dera Ghazi Khan District, Punjab (the holotype, Reg. No. G. 68399, and 3 topotypes, Reg. No. G. 68400-2). Z in d a Lower Chocolate Clays (local zone 1 0 ) (FB. F. 2558, 1,Reg. No. G. 68404; FB. F. 2730,1).
Description.
Shell of medium size, biconic, the spire occupying about one-fifth or one-sixth of the total height. On the holotype the spire is regularly conic except for the extreme apical portion which is extraconic, the average spiral angle being about 90°. On some of the smaller topotypes the spire is more acute and is gently extraconic throughout. In side view the whorls have a height of about one-fifth of their width in the earlier stages, this ratio changing gradually to about one-seventh in the later stages. On a paratype from Domanda, the protoconch was evidently styliform; only the last whorl of it, which is smooth, gently convex, possesses shallow, linear sutures, and is not very high, is preserved. About seven spire whorls separated by distinct, linear sutures; on some specimens they are distinctly stepped, but on others the amount of stepping is negligible, the adjacent anterior portion of the previous whorl having a rounded, not very strongly projecting margin. On the paratype from Domanda the first spire whorl has a projecting median keel which carries distinct, closely spaced crenulations of which there are about nine in half a whorl. On the second spire whorl of this paratype the keel moves to an anterior position, the crenulations becoming weaker. On the later spire whorls of the syntype there are two closely spaced spiral threads adjacent to the posterior suture, the posterior thread being only about half the size of the anterior thread and almost touching both it and the suture, followed by four spiral threads separated by intervals about twice their width and which are in turn followed anteriorly by a rather smooth and rounded band forming the anterior margin of the whorls and occupying the same amount of space as about three of the spiral threads. All spiral threads finely serrated by growth lines. The ornament on the specimens from Safaed is not so clear as they are a little worn, but it appears to be of the same type, although the anterior rounded band appears to be narrower and less distinct on those specimens which have a higher spire and more stepped whorls. All the spire whorls except the first two post-nuclear whorls are gently concave. Body whorl stiffly conic in outline, the shoulder being slightly angular and slightly upturned. Holotype with about 35 incised spiral lines of about the same width as or slightly narrower than their raised, ribbon-like intervals; they are fairly regularly spaced, although a few are finer than others. Smaller specimens show that the raised ribbons become progressively wider and wider until an intercalary incised spiral line appears on most of them, more or less simultaneously, thus almost doubling their number. The relative proportions of the raised ribbons and of the incised spiral grooves therefore vary from time to time during the growth of the shell. Spiral threads near the anterior termination of the body whorl more widely spaced. On the larger paratype from Domanda the spiral ribbons have become spiral bands which are obtusely V-shaped in section, and have intervals of about the same width as themselves; they are rather vaguely crenulated by the growth lines. Growth lines rather strongly convex, noticeably retrocurrent at the shoulder, having a well-defined, U-shaped sinus above the shoulder, and swinging round to meet the posterior suture in an antecurrent direction. Aperture narrow and parallel-sided.
Dimensions.
Holotype: height 22,4 mm .; width 12,6 mm. (possibly slightly incomplete). Paratype from Domanda: width 15,3 mm.
Remarks.
Conus vredenburgi Raj Nath & Chiplonker, from the Upper Middle Khirthar of the Laki dome in Western Pakistan, which also appears to be a Leptoconus, has a higher spire, a less carinate shoulder to the body whorl, is more slender, and has much finer and more closely spaced spiral ornament on the flanks.
Conus orcagnae Oppenheim as figured by Gocev (B 1933 b, pp. 192, 208, PI. 7, fig. 5 ), from the Palaeogene of southern Bulgaria, is somewhat similar in shape, but the incised spiral grooves are restricted to the anterior portion of the body whorl.
Conus deperditus Lamarck as figured by Brongniart (B 1823 , p. 61, PI. 3 , figs, la, b), from Italy, has weaker and more widely spaced spiral ornament on the body whorl, the shell is slightly narrower and less sharply shouldered, and the outline is not so stiff.
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Conus safaedensisFigures 142 a, b, 143, plate 6 Eocene |
Bibliografia
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(1) - Eames, F. A., 1952. A
Contribution to the Study of the Eocene in Western Pakistan and Western
India. Philosophical Transactions of the Royal Society of London, ser. B. vol. 236