Lewis & Short

Prŏconnēsus, i, f., = Προκόννησος, an island in the Propontis, abounding in wine and marble, now Marmora, Mel. 2, 7, 4; Plin. 5, 32, 44, § 151.
Hence,

  1. A. Prŏ-connensis, e, adj., of Proconnessus, Proconnessian: marmor, Sol. 37 med.
  2. B. Prŏconnēsĭus, a, um, adj., Proconnessian: ancilla, Plin. 7, 11, 9, § 49: marmor, id. 36, 6, 6, § 47; 37, 10, 70, § 185; Vitr. 2, 8.