Ceasg

Folktales and compendia portray the ceasg as a water-dwelling female figure of Scottish tradition who inhabits sea, rivers and streams. Scholarly commentary preserved in the collected sources (Donald MacKenzie) suggests an interpretive hypothesis that the figure may derive from an older sea-goddess cult to which humans were once sacrificed; this suggestion is presented as scholarly interpretation in the secondary literature rather than as an origin narrative recorded in the tales themselves.

Standard accounts describe the ceasg as having the upper body of a beautiful woman with long flowing hair and a fish tail — specifically likened to the tail of a grilse (a young salmon). Variant tales describe a form large enough to swallow a human whole; these monstrous versions retain the woman/fish morphology but are notable in the narratives for their capacity to enclose living people within the mermaid's stomach.

Tale-material records several recurrent motifs: a captured ceasg can be made to grant three wishes; ceasgs may marry humans and produce descendants (maritime families and pilots are sometimes reputed to descend from such unions); even after returning to the water a ceasg in stories will take an interest in and protect her human descendants (guiding to good fishing grounds, protecting in storms). In some narratives a ceasg swallows people alive; these tales include a motif where her life-force is externalized in a special egg, and destroying that egg kills her. Music (a harp) is recorded in a tale as capable of charming or pacifying her long enough for an escaped captive to exit her body. A wizard figure appears in narratives as the adviser who instructs a hero to find and destroy the life-egg.