Femur the medial, gives attachment to the fibular collateral ligament of the knee-joint. The femur develops from the limb buds as a result of interactions between the ectoderm and the underlying mesoderm, formation occurs roughly around the fourth week of development. By the sixth week of development, the first hyaline cartilage model of the femur is formed by chondrocytes. Endochondral ossification begins by the end of the embryonic period and primary ossification centers are present in all long bones of the limbs, including the femur, by the 12th week of development. The hindlimb development lags behind forelimb development by 1–2 days.
Tibia fusus cm (9 in.). These shells are large, spindle-shaped with moderately convex turns and an extremely long, thin and slightly curved siphonal canal. The basic color ranges from straw yellow to reddish-beige. The aperture is ovate and white inside, with 6 fingerlike growths on the outer lip. It is a fairly common species where it occurs, but because of its attractive appearance, it is highly sought after by shell collectors. Embryos develop into free-swimming planktonic marine larvae (trocophore) and later into juvenile veligers. Tibia fusus Tibia fusus, common name Spindle tibia or Shinbone Tibia Gastropod, is a species of large sea