I reply to the third of the four arguments for direct reference. The argument was that definition proceeds by genus and specific difference. Therefore a proper name cannot be defined, for they name individuals, and individuals are not species. They have no specific difference, and can only be distinguished by the proper name itself.
I reply by conceding that a proper name cannot be defined, and that a proper name does not signify a species or kind of thing. But I deny that "an individual can only be distinguished by the name itself". As I have argued, signification is not a relation between a name and a thing, and so a proper name does not distinguish an individual in any strict and proper sense (although I concede that in an improper sense it is true that the name 'Frodo' distinguishes a certain fictional hobbit, as I argued here and in other places). We do not learn the meaning of a proper name by definition or by acquaintance with an individual, but rather by acquaintance with the name itself. When we first encounter the name, as Bosanquet says, it has a purely general sense: someone so-called. When we next encounter it, it means the same thing as whatever it meant before. "Aeneas fled his home ... Aeneas was shipwrecked" means simply that someone fled their home and that the same person was shipwrecked. We don't know who Aeneas was in any stronger sense than this.