 The second largest "Myotis" species in the New World, "Myotis velifer", has a skull long, and feet long; "M. vivesi" has greatly elongated hind feet, which average long.In common with other fish-eating bats, "Myotis vivesi" has long, efficient wings, with high aspect ratio and low wing loading, and large feet with sharp claws.The uropatagium (the wing surface between the hind legs) bears a fringe of silky hairs of unknown function; the uropatagium itself is used in hunting.