Among troubadour lyric poetry, the lai Markiol and the lai Nompar have attracted particular critical attention both by virtue of their hybrid linguistic form (a mixture of French and Occitan) and their northern genre provenance. The present new critical edition provides improved readings of the text taking full account of all the information supplied by the melody. There follows an in-depth discussion of the language employed in these versions compared with that found in the 'Occitan' section of the 'chansonnier du roi' (which contains one of them) and other texts of a hybrid linguistic nature, the nearest in this respect proving to be fragment N of 'Girart du Roussillon'. The study thus takes us into a domain of poetic production and tradition of singular interest for the light it casts on the frontier zone between two great literatures, French and Occitan.