(Chapter 10) Footnote 12:

The 1555 edition adds parenthetically β€œfor Galen had, after all, another opinion about apes in the fourth book of De Anatomicis Administrationibus.” The reference is to the following passage: β€œHippocrates says that the lower jaw is compounded of two bones joined together at the end. This has been said by all others who have expounded the nature of the bones with accuracy, yet it is not possible to demonstrate the junction in all apes, for in most of them it will look to you as if the lower jaw were a single bone. In dogs the junction is seen clearly . . .” (2.439.18-440.6, tr. Singer 1956, p. 102).