Complex sentence: Robert de Boron was the author of two surviving poems in octosyllabic verse, the Grail story "Joseph d'Arimathe" and "Merlin"; the latter work survives only in fragments and in later versions rendered in prose.
Split into simpler sentences: Robert de Boron was the author of two surviving poems in octosyllabic verse, the Grail story "Joseph d'Arimathe" and "Merlin". The latter work survives only in fragments and in later versions rendered in prose.