05 Peringia ulvae

05 Peringia ulvae

Suture variation.
Left: 6.5 mm high; shallow sutures and flattened whorls.
From large permanent muddy salting pool, upper Dee Estuary, Flintshire, salinity (variable) 29 p.p.t. .
Right: 6 mm high; deep sutures and rounded whorls. From temporary small pool on wet sand, mouth of Dee Estuary, Cheshire, 33 p.p.t.