43 Rissoa membranacea COMPARE Rissoa parva

43 Rissoa membranacea  COMPARE Rissoa parva

Left: R. membranacea with sinuous lines on angled juvenile body whorl (1).  H. 4.9 mm. Orkney, May 2017. Leg. S. Taylor.  Right: R. parva adult with sinuous lines on curved body whorl (2). Diagnostic brown comma missing from current outer lip (3), but one on previous growth stage (4). H. 4 mm. West Anglesey, Wales. May 2016.

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