ClipArt ETC
"Acorn barnacle, with arms extended." -Cooper, 1887

Acorn Barnacle

"Acorn barnacle, with arms extended." -Cooper, 1887

"a, a', impressions of the muscles; p, pallial line; s, bend occupied by the siphon; h, hinge; c, t, t', teeth." -Cooper, 1887

Clamshell

"a, a', impressions of the muscles; p, pallial line; s, bend occupied by the siphon; h, hinge; c, t,…