Left: stained periostracum removed. Right: periostracum intact.
1: broad spiral ridge. 2: narrow spiral groove.
3: sigmoid costa. 4: costal gap.
5: squared boss. 6: deep, spiral gutter.
7: columellar neck of siphonal canal with 5 grooves (sometimes worn away).
16 to 23 (mean 20.9) costae intersecting with spiral ridges create reticulate arrangement of squarish bosses (Rolan & Luque, 1994).
Height 27.6 mm, Dorset, April 2012.

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