(Chapter 16) Footnote 44:

That is, Galen’s descriptions of human anatomy, the point being that Galen’s anatomy in this regard is more canine than human. Vesalius’ marginal note specifies the error occurs “in De ossibus and elsewhere.” See De ossibus §760: “The transverse processes ... above the tenth [thoracic] slope downward, those following it upward. Those of the tenth only incline neither way.” (tr. Singer 1952 p. 772). This is in his description of the thoracic vertebrae; Galen does not specifically mention the upward-slanting transverse processes that Vesalius alleges he attributed to the lumbar vertebrae.

The remainder of this section was rewritten as follows for the 1555 edition: “The muscles that move the dorsum are the reason why these animals are so different from man in the shape of their spines and transverse processes; these muscles are not as long in man as in the animals, and the way in which the dorsum moves is also quite different. Since we must defer our account of the muscles until the second book, it will now be opportune for us to explain how the ascending and descending processes of the thoracic vertebrae are arranged.”