SOURCE: Odo of Cheriton's' Latin fables are available in Hervieux's edition at GoogleBooks, and there is a delightful English translation by John Jacobs: The Fables of Odo of Cheriton.
This is fable 47 in Hervieux's edition. Although this is not in the Aesopic corpus, the foolish behavior of the monkey fits the spirit of Aesop perfectly.
READ OUT LOUD. Choose which marked text you prefer to practice with - macrons or accent marks - and read the text out loud until you feel comfortable and confident. Then, try reading the unmarked text at the bottom. It should be easy for you after practicing with the marked texts. :-)
MACRONS. Here is the text with macrons:
Sīmia libenter comedit nūcleum, quia dulcis est; sed, quando gustat dē cortice amāritūdinem, nūcleum interius relinquit et nucem proicit.
ACCENT MARKS. Here is the text with ecclesiastical accents, plus some color-coding for the words of three or more syllables (blue: penultimate stress; red: antepenultimate stress):
Símia libénter cómedit núcleum, quia dulcis est; sed, quando gustat de córtice amaritúdinem, núcleum intérius relínquit et nucem próicit.
UNMARKED TEXT. Here is the unmarked text - after practicing with the marked text that you prefer, you should not have any trouble with the unmarked text:
libenter comedit nucleum,
quia dulcis est;
quando gustat de cortice amaritudinem,
nucleum interius relinquit
et nucem proicit.
IMAGE. Here is an illustration for the story (image source) showing a chimp hard at work: