(Chapter 22) Footnote 24:

The final sentence of this section is replaced with the following in the 1555 edition: “ . . . since there intervenes here the special cartilage which we described in the previous chapter because of the ones they wrongly ascribe to this joint as a third bone in addition to the upper process of the sacapula and the clavicle.” Vesalius is referring to the articular disk of the acromioclavicular joint (R in fig. 4).