Psylla resistant.Ragan (1908) lists Spina di Carpi as a synonym for Royal Winter, or Royale d'Hiver.
Royale d'Hyver, or Winter Royal. This is a very large pear, of a pyriform shape, much swelled at the blossom end, and diminished towards the stalk in such a manner as to exhibit a triangular figure when viewed in profile - the skin is smooth and fine, a handsome red towards the sun, yellow on the shady side, spotted with little dots on the red, and russet spots on the yellow - the flesh is half breaking, melting, of a yellowish cast, the juice very saccharine; the eye is very small, and planted very deep - the stalk long, and large at the extremity; the time of ripening is from December to February; in the appearance of this pear and the Muscat Allemand there is little perceptible difference; as delineated by the Abbe Rozier, they resemble each other very much, and it is stated by the same author, that they are frequently confounded by the French gardeners, they are both highly estimable in winter fruits. -- W. Coxe, A view of the cultivation of fruit trees, 1817.