Catalogue entry no. 217 by Max Loehr:
217 Biconvex Knife
The shape of this greenish black blade recalls the trapezoidal knives, but the left edge is curved and the proportions are different. Both the back and the cutting edge are perfectly straight. There are four conical holes along the back, all drilled from the same side; a fifth hole, place along the median close to the fourth one, is drilled from the reverse side. Possibly the blade was originally larger, and was later recut. Western Chou(?).