What is "sancti-johannis"

Roughleg \Rough"leg`\, n. (Zo["o]l.) Any one of several species of large hawks of the genus Archibuteo, having the legs feathered to the toes. Called also rough-legged hawk, and rough-legged buzzard.

Note: The best known species is Archibuteo lagopus of Northern Europe, with its darker American variety ( Sancti-johannis). The latter is often nearly or quite black. The ferruginous roughleg ( Archibuteo ferrugineus) inhabits Western North America.