hylas and the nymphs

The encounter of Hylas and the Nymphs - Giovanni Demin.
Palazzo Papadopoli, Santa Marina, Venice. 

Antoninus Liberalis, Metamorphoses 26 mythographer C2nd A.D. 
“The boy Hylas went carrying a pail to the River Askanios (Ascanius) to fetch water for the leaders [Argonauts]. And when the Nymphai (Nymphs), who were the daughters of this River, saw and fell in love with him, they pulled him in, dragging him down into the spring. After Hylas had disappeared, Herakles saw that he was not coming back to him and deserted the heroes, searching everywhere in the thickets, calling ‘Hylas’ again and again. The Nymphai, fearing that Herakles might discover that they had hidden the lad among them, changed him into an echo which again and again echoed back the cries of Herakles … To this day local people make sacrifices to Hylas by the spring. The priest calls him by his name three times and an echo replies three times.”