(Κασταλία), the nymph of the Castalian spring at the foot of mount Parnassus. She was regarded as a daughter of Achelous (Paus. 10.8.5), and was believed to have thrown herself into the well when pursued by Apollo. (Lutat. ad Stat. Theb. 1.697.) Others derived the name of the well from one Castalius, who was either a simple mortal, or a son of Apollo and father of Delphis, who came from Crete to Crissa, and there founded the worship of the Delphinian Apollo. (Ilgen, ad Hom. hymn. in Apoll. p. 341.) A third account makes Castalius a son of Delphus and father of Thyia. (Paus. 7.18.6, 10.6.2.)
[L.S]A Dictionary of Greek and Roman biography and mythology
Smith, William
A Dictionary of Greek and Roman biography and mythology. William Smith, LLD, ed. 1890