SEC. IV ANATOMY OF BIRDS 241 



pterygoid is always freely iointed at both ends ; its posterior quad- 

 rate articulation has been noted above ; its anterior connection is 

 usually by little nipper-like claws by which it " catches on " to the 

 hind end of the palatine. In the ostrich (Fig. 75, Pt) the pterygoid 

 expands into a scroll-like plate ; but its rod-like shape is usually 

 preserved. Besides passing very obliquely inward as it goes for- 

 ward from the wide-apart quadrates to the narrow rostrum in the 

 axis of the skull, the pterygoid often bellies or elbows inwards in 

 its course to join the basisphenoidal beak, and be movably articu- 

 lated therewith. In the majority of birds there is no such rostral 

 articulation, or the pterygoid only touches the rostrum at its fore 

 end, where it joins the palatal. In many, however, special articu- 

 lar facets, called hasipterygoid processes (Fig. 70, ap), are developed on 

 the rostrum for the pterygoids to abut against and glide over. In 

 Carinate birds, excepting the tinamous (Drommognathce), these 

 processes are forward on the beak, and the pterygoids articulate at 

 or near their own fore ends, as well shown in the fowl or duck 

 (Figs. 77, 78, Pt). In Eatite birds and tinamous, the basipterygoids 

 are very long, flaring transverse processes, far back on the rostrum, 

 at the sphenoidal base, and the pterygoids articulate therewith at or 

 near their own posterior ends (Figs. 75, Btp, and 76). 



The Palatal or Palatine Bones (Lat. palatum, roof of the 

 mouth; Figs. 62, 63, p, 65, 66, 68, 69, 71, 77, 78, 80, pa, 75, 

 76, 79, PI) are a pair, approximately parallel and near the mid-line, 

 forming that part of the " hard palate " or roof of the mouth which 

 is not constructed by the palatal processes of the maxillaries, or by 

 the vomer. They are nearly always long thin bones, among the 

 most conspicuous parts when the dried skull is viewed from below. 

 Sometimes, as in the ostrich (Fig. 75, pi), they are remote from the 

 axis of the skull and only connected in front with the maxillaries 

 and maxillopalatines. In many birds they skip the maxillary parts 

 in going forward to be fused with the premaxillaries ; in most, prob- 

 ably, they form anterior connections in one or another fashion 

 with palatal parts both of maxillaries and of premaxillaries. 

 Behind, they always correctly articulate with the pterygoid. The 

 mid-line connections made in most Carinate birds (not in Dromceo- 

 gmthce) are variously with the vomer, with the rostrum, with each 

 other, or some or all of these relations at once. Along deeply-cleft 

 vomer may by its posterior forks attach itself to the whole palatal 

 mid-line, excluding the palatals from the rostrum ; less extensive 

 attachment of the same kind may permit the palatals to touch each 

 other and the rostrum posteriorly, while cutting them off anteriorly; 

 also, a non-cleft vomer may attach itself to the posterior extremity 

 of the palatals, and bear them off the rostrum. The whole hard 

 palate may fuse into an indistinguishable mass ; and in almost any 



R 



