In the course of his discussion of the relative merits of transformational generative phonology (TGP) and natural generative phonology (NGP), Piggott (1980) introduces as evidence in favour of TGP two phonological changes that took place between Proto-Algonquian and Ojibwa in the following chronological order.: (1) final lax vowel deletion, and (2) the deletion of resulting word-final glides *-w and *-y. By change (1), Proto-Algonquian *elenyiw-a ‘man’ mutatis mutandis became *i/iniw, and by change (2), *iliniw became *i/ini, modern Algonquin dialect of Ojibwa anini. Much of Piggott’s argumentation in favour of TGP rests on certain types of exceptions to these historical processes. In the first type, a Proto-Algonquian form *ne-wi-nteko-wil ‘I am a Windigo [cannibal monster],’ and other verb forms of similar morphemic constituency, underwent final lax vowel deletion and became *ni-wīndigōw, but failed to undergo final glide deletion. This was because the final *-i, unlike the final *-a in *elenyiw-a, an inflectional suffix which does not occur anywhere in the paradigm of the modern word anini, was a derivational morpheme and part of the verb stem, and was retained in non-final position. There it stands in morphophonemic alternation with its own absence, as shown by forms such as ni-wīndigōwi-min < *ne-wi·nieko·wi-Hmena ‘we are Windigos.’ The underlying form of the singular verb is hence ni-wīndigōwi, and the fact that the surface word-final glide -w was not elided is adduced as evidence that the phonological change is better described in reference to the abstract, underlying form rather than the surface form. Since TGP can distinguish between underlying and surface word-final glides and NGP presumably cannot, Piggott claims that TGP can better characterize this change than can NGP.