Ah, an analogous function for nonhomologous structure deriving from an homologous system (of bones).
I'm really surprised that the term _homoiologous_ still hasn't been mentioned. It means "analogous on a homologous base". Granted, outside of university courses and textbooks nobody seems to ever use it, but the wings of birds and bats are the textbook example for homoiology: they're homologous as forelimbs, but analogous as wings.
From Greek homoios/-a/-on = similar.