Ventral view of eight disarticulated valves.
Valve i covers head; valve viii covers posterior.
White interior of valves is articulamentum, a thick layer of white aragonite overlain in parts by myostracum, a thin discontinuous innermost layer only visible in section examined under microscope.
Articulamentum extends beyond dorsal pigmented tegmentum (see image 5Ac 05 Acanthochitona crinita ) to form large rounded apophyses (p) on anterior edge which extend in life under next valve forwards, and two lateral insertion plates, separated by single slit (s), that insert into girdle.
1: anterior white insertion plates on head valve i (magnified ), typically split into six plates by five slits (s), but only two slits clearly developed on this specimen.
2: posterior white insertion plates on tail valve viii (magnified), typically split into three plates by two slits.
Length 26 mm. Disarticulated valves; ii & iii fractured in life, fell apart when girdle and muscle removed. Llŷn, North Wales. March 2016.

KEY ID FEATURES and similar species at: 01 Acanthochitona crinita