The articular surfaces of the haunches (coxae) of the fore-legs are often conical or globular, so that each limb works in a ball-and-socket joint, while the hind haunches are large, displacing the ventral sclerites of the first two abdominal segments (fig.
Many of them, like ungulates, are specialized for swift running, and have unusually long limbs, with ridges developed on the articular surfaces of the lower bones; the clavicles are more or less reduced; the thorax is more compressed than usual, with a narrower breast-bone; and there is a marked tendency to the reduction or loss of the lateral toes, more especially in the hind limb.
Asia and Central America is remarkable for having the dentary bones loosely attached to the apex of the elongated articular bone.
The calcaneum with an articular facet for the lower end of the fibula.
Dentary movably attached to the tip of the articular bone of the mandible.
As a result of this disposition of the articular surfaces, the wing may be shot out or extended, and retracted or flexed in nearly the same plane, the bones composing the wing rotating on their axes during either movement (fig.
Vt', Atlas; Vt2, second vertebrae; a, intercondyloid process of the atlas; b, the articular surfaces for the occipital condyles.
Lower articular surface of the astragalus divided into two nearly equal facets, one for the navicular and a second for the cuboid bone.
This twisting is in a great measure owing to the manner in which the bones of the wing are twisted upon themselves, and the spiral nature of their articular surfaces - the long axes of the joints always intersecting each other b FIG.
I, C) and with their articular surfaces for the toes smooth, instead of ridged as in the Pecora.