Champlain's 1632 map of New France has some truly strange place names for lower New York, which do not appear on his other maps, or on any other maps I know of. Most notably he calls Long Island "Isle de l'Ascension," and the the Hudson River "Riviere de Tretres." I.N. Stokes in his Iconography of Manhattan Island noted these names and remarked that they "call for explanation." I have looked for an explanation of the origin of these names in Conrad Heidenreich's book on the Explorations and Mapping of Samuel de Champlain, and in several other recent books, but so far without success. Has anybody encountered an explanation of the source of these names? (I suspect that they derive from some French exploration of the New York area between 1610 and 1630.)