Scissurella costata d’Orbigny, 1828
Galicia to Mediterranean.
Grazer and deposit feeder in the infralittoral down to the continental shelf. The synonymy describes the species: cancellata, decussata, plicata, striatula
250m deep, Alborán island. 1,3-1,5mm.
D’Orbigny describes the new genus Scissurella as follows: « Shell univalve, free, umbilicated, with a lowered spire; aperture subcircular, without canal, lips disunited and without peristome; their right edge is cut by a deep fissure that followed the increase of the whorls, obliterated itself at a small distance from the edge of the aperture, and traced on the back of the shell a kind of keel. » – A. D. d’Orbigny: “Monographie d’un nouveau genre de mollusque gastéropode de la famille des trochoides”, Mémoires de la Société d’Histoire Naturelle de Paris series 2 vol. I, Paris 1824, p.343.

150m deep, Messina Strait, SW. Italy. 1,75mm.
« Shell oval, white, translucent, fragile, with a flattened summit, having three whorls, the top of which is furnished with high transverse ribs spaced from each other, and whose underside shows the same ribs but more salient and practically sharp; the space between the coasts is almost united and shows only very slight roughnesses. The two edges of the fissure form two beads which leave between them, in the obliterated part, an interval marked by close and very pronounced transverse lines; the umbilicus is surrounded by circular striae, the mouth is almost quadrangular, the lips are sharp. »op. cit. p.344.

Above, the species in d’Orbigny, op. cit. plate XXIII.
Scissurella costata in A. Vayssière: “Étude zoologique de la Scissurella costata var. laevigata”, Journal de conchyliologie, series 3 vol. XXXIV, Paris 1894.
« Animal of a hyaline yellow-whitish colour, with purplish markings. […] Test carinated with three whorls on the spire, oval, with a flatten summit ; carina rather large and deep ; transversal striae quite pronounced, longitudinal striae weaker ; some costae on the two first whorls, usually almost fading at the beginning of the third one. Color yellowish-white to greyish brown. […] Rather common in all european waters, but especially in the Mediterranean. Along our coasts I always met with it amongst debris of Zosteras ; it appears not to inhabit in less than 10m of depths, down to 35-40m ; it lives on all the bottoms with coralligen or Zosteras… »
Animal white mottled purple. In tide pool with Valonia utricularis (Roth) C. Agardh, 1823, Split area, S. Croatia. Notice how the puple dots gather along the margin of the foot. Original picture provided by P. Ugarković (HR).
Heavily sculptured specimen from beach drift,
Palavas-les-flots, Gard, S. France. 1,04mm.
Original pictures provided by S. Clanzig (FR).
25m deep, in sediments, between Sapri and Acquafredda, S. Campanian border, SW. Italy. 1,4-1,6mm.
Same spot. 1,5mm.
52m deep, Scilla, Calabria, SW. Italy. 2mm.
On detritic sand, 10-12m deep, Vignola Bay, Marina di Davia, Corbara, NW. Corsica. 1,4mm.
Original pictures provided by S. Clanzig (FR).
Microsculpture on a fairly smooth specimen from 40m deep, off le Scole, isola del Giglio, Toscana, W. Italy.
Left: between suture and selenizone; right: on the base.
26m deep, Punta de la Mona,La Herradura, Granada, Andalucia, S. Spain. 1,8mm. Notice the minute protoconch of one whorl.

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