The palatine bones

The palatine bones are generally long and concave on their palatine faces. In front, they pass beneath (i. e., on the ventral side of) the maxillo-palatines and unite with the premaxillae, sometimes by a squamous suture, sometimes by anchylosis, rarely, as in the Parrots, by a flexible joint. Posteriorly, they always unite with the pterygoids. In most birds, the palatines converge, posteriorly, toward the basi-sphenoidal rostrum, and unite with it by an articular surface, which allows of a sliding motion of the palatines upon the rostrum. Such an articulation does not exist in Ratitae, or in the Tinamous, among the Carinatae. In these (with the exception of Struthio), the palatines are, as it were, borne off from the rostrum by the divergent ends of the great vomer, and the disposition of the parts is more lacertilian than in other birds, The outer, or posterior, end of the pterygoid bone presents a fossa for an articular head, which is developed upon the inner side of the distal end of the quadrate. The inner, or anterior, ends of the pterygoids meet in almost all birds, and may become articulated with the basi-sphenoidal rostrum. In all embryonic birds, in all the Ratitae, and in many Carinatae, such as the Tinamomorphoe, Charadriomorphae, Alectoromorphae, Peristeromorphae, Chenomorphae, longer or shorter processes extend from the basi-sphenoid, and present terminal articular facets to corresponding facets upon the inner sides of the pterygoids. These are basi-pterygoid processes, similar to those which occur in Lacertilia and some Ophidia.