The proximal ends of the ribs expand dorsoventrally to a width
approximately four times that of their slender shafts. The tuberculum
and capitulum on each of the trunk ribs are separated only by a shallow
concavity. These two articular surfaces are so situated that the rib
must tilt downward from the horizontal plane. The shaft flares
terminally in some ribs, and the distal end is convex. Ribs in the
trunk region differ little if any in size. Five that can be measured
vary in length from 5.0 to 7.0 mm. One short, bent rib 3.5 mm. long
perhaps is sacral or caudal.