Potamides

[2] And many of these hellish potamides, the Avernales, were believed to be owners of prophetic ability, and to express that gift to their chosen men.

[8] It was believed by the ancients that they carried water for their river parents,[8] as was quoted: "In the lonely hour of noon the naiads sat with their water-pitcher at the spring-sending forth from it the warbling brook.

Thus potamides, and nymphs in general, were conceived to be endowed with oracular power, to inspire men with the same prophetic gift, and to bestow upon them the natural talent of poetry.

[2] Accordingly, in many parts of Greece, offerings of honey, oil, milk, but never of wine, and sometimes sacrifices of a lamb or goat[2] were presented to these divinities.

Although they had no temples,[11] the most beautiful spots in forests, gardens, and so forth, were regarded as the favorite places of nymphs and invisible spirits and thus esteemed with special veneration.

Hylas and the Water Nymphs by Henrietta Rae , 1909.
The Nymph's Bathing Place by Edward Poynter , 1904.
Potamides in a river. Nymphes au bain by Auguste G. L. Desnoyers , 1830.