Adam Clarke on Acts 28:7

The chief man of the island - The term πρωτος, Chief, used hereby St. Luke, was the ancient title of the governor of this island, as is evident from an inscription found in Malta, which runs thus: - Λ. Κ. υἱος, κυρ. ἱππευς. ῥωμ. πρωτος Μελιταιων·

Lucius Caius, son of Quirinus, a Roman knight, Chief of the Melitese. See Bochart, Phaleg. and Chan. vol. i. chap. 498, etc., and Grotius. This title is another proof of the accuracy of St. Luke, who uses the very epithet by which the Roman governor of that island was distinguished.