 They also have a distinctly keeled calcar (cartilagenous rod on the hind legs to support the interfemoral membrane).Their forearm length, which is less than 34 mm, can be used to distinguish them from all other Myotis in Eastern North America.Tail is between 25-45 millimeters in length and protrudes past their interfemoral membrane, and they have a dental formula of 2/3, 1/1, 3/3, 3/3.