Complex sentence: There is little visible difference between the sexes in most of the family, although in several species the iris is red in the males and brown-red in the females, and in species with tail-streamers these may be slightly longer in males.
Split into simpler sentences: There is little visible difference between the sexes in most of the family. In several species the iris is red in the males and brown-red in the females, and in species with tail-streamers these may be slightly longer in males.