[356] Turchill, c. 1200.
[357] Anon. MS., thirteenth century, Alexandrian Library, Rome.
[358] Twelfth-century Boethius, Friedlein, p. 396.
[359] Vatican codex, tenth century, Boethius.
[360] a, h, i, are from the Friedlein ed.; the original in the manuscript from which a is taken contains a zero symbol, as do all of the six plates given by Friedlein. b-e from the Boncompagni Bulletino, Vol. X, p. 596; f ibid., Vol. XV, p. 186; g Memorie della classe di sci., Reale Acc. dei Lincei, An. CCLXXIV (1876-1877), April, 1877. A twelfth-century arithmetician, possibly John of Luna (Hispalensis, of Seville, c. 1150), speaks of the great diversity of these forms even in his day, saying: "Est autem in aliquibus figuram istarum apud multos diuersitas. Quidam enim septimam hanc figuram representant
[361] Loc. cit., p. 59.