The Lamiak (sing. Lamia/Lamina), water-nymphs of Basque rivers, springs and fountains: beautiful, long-haired, with the feet of a duck or bird (or a fish-tail by the sea), combing their hair with a golden comb. They build bridges and dolmens overnight and aid those who leave them offerings. Treated as a collective/type figure. Documented by Barandiarán and Webster (secondary).
Domains
rivers springs and fountains
craft of night building
Powers
Sit at the water's edge combing long hair with a golden comb
Build bridges, dolmens and houses in a single night in exchange for offerings
Aid farmers and households who leave food, finishing fieldwork by night
Sources
J. M. Barandiarán, Diccionario ilustrado de mitología vasca, s.v. Lamia / Lamina
W. Webster, Basque Legends (London, 1879), tales of the laminak