Hydrobia ulvae. Black arrow; umbilical chink. Adapical end of aperture pointed. Base of aperture (grey arrows) elongated on right specimen (height 4.4mm), more rounded with thicker lip on left specimen (height 5mm). Deep sutures. Mouth of Dee, Cheshire.
Hydrobia ulvae. Black arrow; umbilical chink. Adapical end of aperture pointed. Base of aperture (grey arrows) elongated on right specimen (height 4.4mm), more rounded with thicker lip on left specimen (height 5mm). Deep sutures. Mouth of Dee, Cheshire.
Hydrobia ulvae. Black arrow; umbilical chink. Adapical end of aperture pointed. Base of aperture (grey arrows) elongated on right specimen (height 4.4mm), more rounded with thicker lip on left specimen (height 5mm). Deep sutures. Mouth of Dee, Cheshire.
