baffled by the sound , he continued on in his less-than-productive crouch for several more strides , his mind working feverishly to construct a picture of his attacker : tent posts for teeth , wet mattresses for head and body , boat sails for wings the last detail seemed fantastic even for a creature of the bottoms , but any lingering doubt was quickly relieved as the fog around him began to twist and swirl , turning lightly at first and then picking up speed , eventually streaking past him in a blur .