Reinforcing bark was placed under the outwales in all Mackenzie Basin canoes, but not in the Alaskan or in the bateau variation. The ribs in all these canoes were small, usually about ½ inch square, and widely spaced, about 9 to 14 inches on centers. No ribs were placed in the rake of the ends. The ends of the ribs were chisel-pointed and were forced between the inwale and outwale, against the inside of the bark cover. In some canoes, however, the ribs near the ends of the canoe were forced into short splits on the underside of the inwale. The thwart ends might also be forced into short splits on the inside face of the inwales or might be tenoned there; in any case a single lashing was used at the thwart ends. Thwarts were parallel-sided in plan and slightly tapered toward the ends in elevation; no shoulders were used. In the bateau variation, a heavy thwart was placed directly under the middle thwart with its ends against the side battens, apparently to act as a spreader. Each end was notched over the side battens and was held by two lashings to the bottom crosspiece below it. This structure was probably made necessary by the fragile construction of this form of canoe. In all kayak forms there was no complete sheathing--the one, two, or three narrow battens to a side above the chine were held in place only by the sprung ribs (without lashings); in the bateau form, however, the side batten was lashed to each frame after the manner of of an Eskimo sea kayak. The characteristic detail in the structure of the bark kayak-canoe, including the bateau variation, was the bottom framing. It was variously formed, according to tribal designation. The bottom framing was made up of five or six longitudinal battens (four in one extinct form of canoe). In the Yukon canoes six rectangular battens, all of about the same cross section, were used with the narrow edge outboard. These battens were held rigidly to form by thin crosspieces, or splints, about ¼ by 1 inch forced athwartships through short splits in the battens and pegged at the ends on the chine battens. The ends of the four inner longitudinals were cut off on the snye to bear on the inside face of the chine battens (in some instances they were cut short of this). The chine ends were beveled together or lashed to the sides of the stem-pieces. But in the Mackenzie form of canoe, the longitudinals had no cross-members and, like the side battens, were held in place by the pressure of the sprung ribs against the bark cover. There was a difference in the form of midsection: in the Yukon canoes the bottom athwartships was flat, but in the Mackenzie canoes there had to be some rounding there. At least one exception existed in the Mackenzie Basin, where the Loucheux canoe was formed on the Yukon bottom. Another is to be seen in an old model of an extinct Athabascan kayak form, which has only four longitudinals and chine members that are very wide and rounded only on the outboard face. Between the chine