(Chapter 15) Footnote 47:

The 1555 edition continues the sentence “ . . . in which the capitula of the occiput are flexed and extended or moved forward and backward in a very straight and by no means sidewise inclining movement.” Everything after this point up to the section titled “The Remaining Description of the First Vertebra” was reworked and added to the end of the chapter in the 1555 edition. See Appendix.