Hi Marc,
Glad you had a chance to look at the Museum bows again. Besides the close up side view (some glass glare) which shows that at least for the two bows to the left the side with the belly ridge is the one that has a slope to both sides of the handle into each limb and it appears from what I can see the back is flat.
I am including another somewhat darker picture again from the side view that show that the two bows to the left show clearly some set bent towards the observer when standing in front. I can always post in a photo link a higher resolution of the picture if you have trouble seeing it. The bow on the right is a much heavier draw weight bow and also longer with the widest point in each limb in the middle of those limbs. I am still somewhat confused on that one which side is which. I have written to the Museum to see whether they have front and back pictures of the bows which would of course would be very helpful to get the complete picture on those bows.
On page 168 of the Traditional Bowyers Bible Volume One, Steve Allely describes some of the bows he has seen from British Columbia and some cross sections of those profiles are shown as well besides their description.
The profiles form those museum bows look a lot like profile "D" (Nootka) except that it doesn't have the concave ridge but a rounded ridge instead with double concave sides. Steve actually states that some of the bows he has seen had ridges running down the middle both the back and on the belly others had it only on the back like in profile "E" depicted on the same page 168. But that one is more like flat triangle.
Again hopefully someone will write back to me from the Museum so we can clear up the mystery.
If Steve still frequents these pages, it would be cool to hear from him on the subject, maybe he has some pictures of some of the bows he has seen that had the ridges.