240 GENERAL ORNITHOLOGY part ii 



quadrate, at the inner side of the main facet, socketed into the 

 cupped end of the pterygoid (with minor modifications). 



The Quadratojugal and Jugal Bones (Lat. jugum, a yoke; 

 Figs. 62, 63, q, r, 69, 71, gi, j) form most of the outer arcade — the 

 jugal or zygomatic bar — leading from the quadrate bone to the beak. 

 The quadratojugal is posterior, reaching a variable distance for- 

 ward ; at its fore end it is obliquely sutured to the jugal, a splint- 

 rod which carries the bar forward to the maxiUary bone, with which 

 it is in like manner obliquely sutured. The whole aflFair is almost 

 always a slender rod, which, with its fellow of the opposite side, 

 forms the outermost lateral boundary of the skull for a great dis- 

 tance. It corresponds in general with the " zygomatic arch " of a 

 mammal, which is made up of a " zygomatic process of the squa- 

 mosal " and a malar or " cheek-bone." The whole zygomatic arch, 

 including the maxillary bone itself, is developed from the outer part 

 of the primordial pterygopalatine bar (see Fig. 65). In parrots the 

 zygoma is movably articulated before as behind. 



The Maxillary Bone (Lat. maxilla, upper jaw-bone; Figs. 62, 

 '63, s, 69, 71, 75, mx), forming so much of the upper jaw of a 

 mammal, is in birds greatly reduced, being starved out by the pre- 

 dominant premaxillaries which form most of the upper beak. The 

 shape of this stunted bone varies too much to be concisely described. 

 Its connections are, ordinarily, with the jugal behind, by a long 

 slender splint-like process, and with the premaxillary and usually 

 the nasal bones in front and externally. Internally, it may or may 

 not connect with the palatal and vomer. The zoological interest of 

 this bone centres in certain inward (palate-ward) processes, often its 

 most conspicuous parts, and apparently corresponding to the plate 

 which in a mammal roofs the hard palate anteriorly. Though these 

 are mere processes from the main maxillary, they are so distinct 

 and important that they are commonly described as if they were 

 independent bones, under the name of the maxillopalatines. They are 

 flange-like or scroll-like plates, or large spongy masses of delicate 

 bone-tissue, — endlessly varied in configuration and context (see the 

 various figures of base of skull, mxp, beyond, where the palatal 

 patterns are described). Certain other inward maxillary processes, 

 which may or may not unite with the vomer, and so bridge over 

 the palate, are called sepfo-maxillaries (Fig. 80, smx) ; and in some 

 woodpeckers yet other palatal processes appear (Fig. 80, pmx). 



The Pterygoid Bones (Gr. irrepv^, pterux, wing; elSos, eidos, 

 form; Figs. 62, 63, o, 65, 66, 68, 69, 71, 80, pg, 75 to 79, Pt). 

 Returning now to the quadrate, and going along the inner arcade, 

 we first encounter the pterygoid, — a generally rod-like, but variously 

 twisted, crooked, or expanded bone, which makes the connection 

 between the quadrate behind and the palate bone before. The 



