(Chapter 6) Footnote 33:

The letters engraved in this figure, particularly B, C, D, and E, are nearly unintelligible in the 1543 and 1555 editions available to us. The figure was apparently recut at some later date, however, and they are visible in modern reprints such as Saunders and O’Malley’s Illustrations from the works of Andreas Vesalius of Brussels (1950, 1973), p. 56.