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"Section of Ammonites obtusus, showing the interior chambers and siphuncle." — Chambers' Encyclopedia, 1875

Ammonite

"Section of Ammonites obtusus, showing the interior chambers and siphuncle." — Chambers' Encyclopedia,…

"Pearly Nautilus. e, eye; h, hood, a muscular portion of the foot which protects the softer parts; s, siphon; se, septa, separating the successive chambers of the shell; sp, siphuncle; t, tentacles." — Galloway

Pearly Nautilus

"Pearly Nautilus. e, eye; h, hood, a muscular portion of the foot which protects the softer parts; s,…