36 Rissoa membranacea,

36 Rissoa membranacea,

Mediterranean form. Beached specimens. Fairly tall spire of six whorls with subsutural collar (1). Well developed ribs overhang suture (2) to give a tiered flounced effect that enhances tumidity of whorls. A similar feature is seen on some Atlantic specimens, see 33 Rissoa membranacea.  

Zaton, Croatia. Leg. © A. Petani.

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