1911 Encyclopædia Britannica/Glaucus 1.

1. Glaucus, surnamed Pontius, a sea divinity. Originally a fisherman and diver of Anthedon in Boeotia, having eaten of a certain magical herb sown by Cronus, he leapt into the sea, where he was changed into a god, and endowed with the gift of unerring prophecy. According to others he sprang into the sea for love of the sea-god Melicertes, with whom he was often identified (Athenaeus vii. 296). He was worshipped not only at Anthedon, but on the coasts of Greece, Sicily and Spain, where fishermen and sailors at certain seasons watched for his arrival during the night in order to consult him (Pausanias ix. 22). In art he is depicted as a vigorous old man with long hair and beard, his body terminating in a scaly tail, his breast covered with shells and seaweed. He was said to have been the builder and pilot of the Argo, and to have been changed into a god after the fight between the Argonauts and Tyrrhenians. He assisted the expedition in various ways (Athenaeus, loc. cit.; see also Ovid, Metam. xiii. 904). Glaucus was the subject of a satyric drama by Aeschylus. He was famous for his amours, especially those with Scylla and Circe.

See the exhaustive monograph by R. Gaedechens, Glaukos der Meergott (1860), and article by the same in Roscher’s Lexikon der Mythologie; and for Glaucus and Scylla, E. Vinet in Annali dell’ Instituto di Correspondenza archeologica, xv. (1843).

All the above are exhaustively treated by R. Gaedechens in Ersch and Gruber’s Allgemeine Encyclopädie.