de Varietate (Google Books ⧉, Amazon ⧉, Bookshop ⧉)

The Travels of Marco Polo

…as may be seen in Jerome Cardan’s description of a unicorn’s horn which he saw suspended in the church of St. Denis; as well as in a circumstance related by P. della Valle (II. 491; and Cardan, de Varietate, c. xcvii.).