13 Testudinalia testudinalis. Length 2mm. Littoral. Great Cumbrae, Scotland. August 2017. © P. Lightfoot.

13 Testudinalia testudinalis. Length 2mm. Littoral. Great Cumbrae, Scotland. August 2017. © P. Lightfoot.

Left: interior view.
Dark viscera visible through translucent foot. Red/pink of odontophore visible in head. White pallial tentacles visible bottom left against brown band on shell.
Right: exterior view.
The thin, transparent, juvenile shell shows the green mantle and the central, dark, amphora-shape mark on the interior of the shell.
This 2mm specimen in August is a product of breeding earlier in spring or early summer of the same year.

APPENDIX re range advance/retreat: flic.kr/p/2jW74ig

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