Kennebec and Skowhegan have to be taken off the table because the heart-shaped deck wasn't mahogany--- their mahogany trimmed canoes had decks with coaming. I know the Kennebec records didn't correspond with the canoe in question, but the heart is such a similar shape that I wondered about the Skowhegan until I re-read the info on it.
Greg-- you may want to look over discussions of the suggested canoe-species at
www.dragonflycanoe.com/id/ and see what you think. Scroll to the types that have been suggested (on the left). You can also use the "search" function (above) to find past discussions of these canoes, many of which will have pictures.
Note that Carleton canoes have had heart-decks throughout production, not just the early ones. The reason for focusing on the early ones has to do with the low serial number on the canoe in question.
Charles River canoes-- can't think of any with heart-shaped decks. The heart deck is maybe the commonest shape, overall, so it almost seems (to me at least) that the Charles River builders avoided it--- maybe wanted to come up with something unique.
This canoe would be considered "first grade", with the mahogany trim and half ribs. Does it seem that it had open gunwales? It seems unusual to me that a first-grade canoe would be used as a camp canoe. But maybe the camp was the second owner. Or it was a ritzy camp with a fleet of mahogany trimmed highly rare canoes by someone who only built canoes for that particular camp and to keep wooden canoe enthusiasts in the future speculating...
Planking pattern isn't anything like any of the canoes in our barn. Seems unusual to me.