THE ANATOMY OF BIBBS.— OSTEOLOGY. 



173 



segithognathous type ; it is frequently massive in that direction, and of endlessly varied con- 

 figuration. 



Saurognathism, — (Gr. travpos, sawos, a lizard; fig. 80). According to Huxley the 

 woodpeckers exhibit a " degradation and simplification of the segithognathous structure." The 

 peculiarities of the palate of these hirds (including Picidce, Picumnidee and lyngida) are so 

 decided that Parker proposes to caU them saiirognathous. The structure is very difficult 

 to make out, and may be understood best by 

 study of the accompanying figure, copied from 

 Parker. The maxUlo-palatines, mxp, are 

 very slight, not extending inward beyond the 

 outer margin of the palatines, and being some- 

 times quite rudimentary. In front of them, 

 an additional little palatal plate of the max- 

 illary, pmx, is developed. The vomers, v, are 

 delicate paired rods on each side of the median 

 hue. The postero-extemal angle of the pala- 

 tine is either rounded off or obtuse-angled. 

 Where the broad main part of the palatine 

 suddenly narrows is developed an interpala- 

 tine process, ipa. The ethmo-palatine plates, 

 epa, or internal superior plates of the palatine, 

 which are of variable length, are connected 

 by the most marked medio-palaUne ossifica- 

 tion, mpa, seen in the class of birds. Bridges 

 of bone are deposited along the inner borders 

 of the palatines; such are the septo-maxil- 

 laries, smx, and other formations which, like 

 the medio-palatine, serve to bind the palate 

 halves together. The nasal chambers are 

 unusually simple ; there are peculiarities of 

 the tympanic cavity and quadrate bone. 



"All these things being considered," 



says Parker, in conclusion, "it will seem con- 

 tradictory now to assert the great uniformity 

 of the skulls of Birds, and indeed of Birds 

 themselves. Yet so it is ; and the countless 

 modifications that offer themselves for obser- 

 vation are gentle in the extreme. One form 

 is. often'^een to pass into another by almost 

 insensible gradations. ... In the rest of the 



fiG. 80. — SawrognatTums skull of nestling PixMs 

 X 4 diameters, after Parker. Px, premaxillary; 

 dpx^ its dentary process; ppx, its palatal process; sn, 

 septo-nasal ; pa, palatine ; pmx, peculiar palatal plate of 

 maxillary of a woodpecker; 7?/, nasal turbinal; mx, 

 maxillary ; ipa, interpalatal spur of palatine bone ; mxp, 

 rudimentary maxillo-palatine, scarcely reacMng palatine ; 

 smx, septo-maxillary, in several pieces ; i\ right vomer, 

 its fellow opposite ; pe, lower border of perpendicular plate 

 of ethmoid, between vomers; epa, ethmoidal (inner) 

 plate of palatine ; mpa, medio-palatine ; pg, pterygoid ; i, 

 foramen for internal carotid; 8, for vagus nerve; 9, for 

 hypo-glossal nerve. 



Birds' organization abundant evidence of the 

 same specialization wUl be seen. The mind fails to desire more beauty or to contemplate more 

 exquisite adaptations. An almost infinite variety of Vertebrate life is to be found in this class. 

 Of its members some dig and bury their germs, which rise again in full plumage, whilst others 

 watch and incessantly feed their tender brood in the shady covert or ' on the crags of the rock 

 and the strong place.' In locomotion some walk, others run, or they may wade, swim, plunge, 

 or dive, whilst most of them 'fly in the open firmament of heaven.' " {Ency. Brit. 9th ed. 

 Art. Birds, p. 717.) 



