1. Rudimentary vestigial shell from mature animal. Height (longest dimension) 18mm, about 30% length of animal. Caithness, Scotland. June 1975.
2. Rudimentary vestigial shell from mature animal. Height (longest dimension) 18mm, about 30% length of animal. Caithness, Scotland. June 1975.

Rudimentary vestigial shell from mature animal. Height (longest dimension) 18mm, about 30% length of animal. Caithness, Scotland. June 1975.