The Toffee's Under-19s Technical Manager Neil Dewsnip told their official site: "We found it difficult for Craig to get a regular game of football so in the
best interests of his development, we thought it best for him to take this
opportunity.
"Hull are desperate for a 'keeper, so we've allowed him to help them out,
but hopefully it will help him as well."
Gallagher is one of two goalkeepers currently on loan at the KC Stadium. Stuart Brock was recently brought in from Telford as backup for Boaz Myhill due to Matt Duke's back injury.