The author concludes his investigations concerning the modifications occurring at the bar and entrance of the lagoon region of Cananéa (State of S.Paulo, Brazil). In the first part of the paper data gathered in the last year (1954) are presented and by means of two graphs and a sketch the progress of the phenomena of erosion and accretion are demonstrated. In the second part a description, in various phases, of the development of a "restinga" (spit or bar of sand) is given, documented by sketches and several photos. In the third part considerations are made about the variation of the bar secondary channels and an interpretation of the process is given.