Answer: floating (vertebral) ribs
Explanation:
In a typical vertebrae there are 12 pairs of ribs. Each rib is a flattened bone with curvature. These ribs contributes to the wall of the thorax. The last 2 pairs of ribs are not connected with the sternum bone and it's associated cartilage. These ribs are called as the floating ribs. The floating ribs are attached with the vertebral column. These ribs are small and relatively delicate as compared to other pairs of ribs. These ribs include a cartilaginous tip.
