ðeɪ ɑːɹ ɚɹˈeɪndʒd ɪn ɐ sˈɜːkəl, ænd fˈɔːɹm ɐ sˈɔːɹt ʌv fɹˈɪl bᵻhˌaɪnd ðɪ ˈaɪɹɪs, ɚɹˈaʊnd ðə mˈɑːɹdʒɪn ʌvðə lˈɛnz.
They are arranged in a circle, and form a sort of frill behind the iris, around the margin of the lens.