Chelyconus
ralphii (Tenison-Woods, 1879)
Description.
Shell small, rather narrowly ovate, with a somewhat produced spire rising in stages, which are very distinctly granular, the granules being square and large. The upper part of the whorls is grooved with a few lines, and this grooving extends over the angle of the last whorl, causing a kind of granular margin (3).
There is no other ornamentation on the body-whorl, except about ten spiral striae near the base, but the lines of growth are very apparent. The species is like the Vienna miocene C. extensus Partsch in its young stage, but in that shell the spire is more acute and longer. In our fossil, the upper part of the whorl near the suture is faintly channelled. The granules are also different, and the anterior striae are more numerous and finer.
Conus dujardinii is like it in form, and C. antediluvianus has the corona more marked with a deep sinus near the suture. Both the latter belong to the Vienna miocene. There is nothing at all like it in the Paris basin; and we have nothing very similar existing in Australia but Conus anemone f. carmeli, mihi, which has the two last whorls only coronate, but is distinctly grooved all over, and is broader in proportion to length. I have dedicated this interesting specimen to Prof. Ralph Tate (3).
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Conus ralphii (3) Plate 21 fig.
14 |
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[Andrea Petri] |
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Denial Bay,
Australia [Paul Kersten] |
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Conus ralphii Middle Miocene
(Balcombian) mm. 42,7 x 21,2 Middle Miocene
(Balcombian) Muddy Creek
Formation, Clifton Bank, Muddy Creek 7 km west of
Hamilton, Vistoria, Australia [AZFC 557-01] |
Shell
pyriformly oval, with a moderately elevated broadly conical spire, ending in a
small naticiform pullus of one and a half smooth whorls. Spire-whorls seven,
plane or flatly convex, separated by a slightly channelled suture, which is
crenulated, or even nodulated, at the posterior margin of the earlier whorls ;
ornamented on the posterior-half of each whorl with usually three conspicuous
equidistant incised spiral lines. Body-whorl bluntly rounded, rarely
subangulated, at the periphery ; ornamented on the posterior slope with a few
incised lines, the rest of the surface varying from smooth to faint
spirally-linear-grooved, punctatedly impressed ; the base is usually spirally
wrinkled, but sometimes inconspicuously so. Aperture narrow, obliquely incurved
at the posterior angle ; outer lip slightly ecurved medially (1).
Dimensions. —
Length 40 ; greatest width, 21 ; length of aperture, 34 ; height of body-whorl,
35 (1).
Localities. —
Very common at Muddy Creek ; rare in the calciferous sandstones of the River
Murray Cliffs, near Morgan (1).
The species
varies slightly in the height of the spire and in the proportion of the width
to the length, also the spire-whorls may show a slight convexity and even a
perceptible angulation at the posterior margin of the suture; rarely does the
nodose crenulation continue beyond the fourth whorl. C. Ralphii was
founded on a very young individual, 10 mm. in length, at which stage of growth
there are only four spire-whorls, but from an authentic specimen of that size I
have traced it, through many intermediate stages, to the adult example which is
here figured. The comparisons made by the original describer with certain
species of the Viennese Miocene and with C. Carmeli of Australian waters
are now no longer applicable, as the coronation of the whorls of our fossil is
a character restricted to juvenile examples (1).
Protoconch
(Plate II. Figs. 9a-b) conical,
moderately elevated and composed of two smooth turns, somewhat similar to that
of C. heterospira. In the brephic stage, and, possibly, to the
commencement of the neanic, the whorls of the spire are coronate, but as the
adult form is reached these disappear and the shoulders become rounded. Mr.
Tenison-Woods was only acquainted, apparently, with young forms of the species,
and the figure in his memoir cited above does not convey a correct idea of the
shell, as each whorl is represented as being carinate and nodosely crenulated.
Professor Tate has traced the young forms to the adult and firmly established
the species. The spire is elevated, composed of eight whorls striated spirally
above. The body-whorl is also spirally striated, the striae being most
conspicuous on the anterior half. Aperture narrow, posterior sinus shallow and
following growthlines ; columella slightly twisted anteriorly (2).
Dimensions
—Length 43 mm. ; breadth 23 mm (2).
Form, and
Loc.—Eocene : Muddy Creek, Victoria (2).
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Conus ralphii (2) |
Bibliografia Consultata
·
(1)
- Tate (1890) – “TRANSACTIONS AND
PROCEEDINGS REPORT OF THE ROYAL SOCIETY Of SOUTH
AUSTRALIA”: pag. 199
·
(2) - CATALOGUE TERTIARY MOLLUSCAIN THE DEPARTMENT OF GEOLOGY BRITISH
MUSEUM (NATURAL HISTOHY). PART I. THE AUSTEALASIA TERTIARY MOLLUSCA. GEOEGE F.
HARRIS, F.G.S.,