Lewis & Short

pĕlăgĭum, ii, v. pelagius, II. B.

      1. 1. † pĕlăgĭus, a, um, adj., = πελάγιος, of or belonging to the sea, sea- (pure Lat. marinus): pelagii greges piscium, Varr. R. R. 3, 3, 10: pelagiae conchae, sea-mussels, Plin. 9, 29, 46, § 85: cursus, Phaedr. 4, 20, 7: matrona ornata phaleris pelagiis, i. e. with pearls and corals, P. Syrus ap. Petr. 55
  1. II. Subst.
    1. A. pĕlăgĭa, ae, f., a kind of pearl-mussel, Plin. 9, 37, 61, § 131.
    2. B. pĕ-lăgĭum, ii, n., purple color, Plin. 9, 38, 62, § 134; 9, 40, 64, § 138.