Butterflies have three segments, a head, thorax, and abdomen. They have antennae and  external mouthparts on the head, six legs on thorax, and organs in the abdomen. Mylitta Crescents are considered a Brush-Footed butterfly, which means like all insects they have the six legs, but the two front legs are very small and covered with bristles, which makes them appear to only have four legs. Other Brush-Footed butterflies include Monarchs, Buckeyes, Mourning Cloak, Fritillaries and more. Crescents are small butterflies that have much pattern variance. The Mylitta Crescent is a common butterfly in mountain meadow areas, which is where I saw this one in northern Arizona.