PEOF. W. K. PAEKER O:^- .EGITHOGNATHOUS BIEDS. 303 



The fledgeling shows how ichthyic the maxillaries remain, even in this high type 

 (fig. 1, mx) ; they wedge in below the dentary and palatine processes of the preemaxil- 

 laries, and then, growing broader, send inwards the gi-eat slanting spatulate maxillo- 

 palatine spur (mx.j)). This has a struthious coarseness now, but becomes elegant in its 

 curves and scoopings afterwards (fig. 6), and acquires a distinct pedicle. That pedicle is 

 much more slender and defined in many of the feebler forms that crop up around the 

 true " Corvidee ;" and its form, ruder or more elegant, is very useful as a mark of high 

 or low breeding in any type. The long jugal style (/) has no quadrato-jugal subdivision, 

 but binds directly on the quadrate. 



This latter bone and its relationships, although not coming within my stricter plan, 

 has to be brought in here. It curves backwards (fig. 7, q) to be articulated with a raised 

 facet common to the periotic and exoccipital regions : this " otic process " is merely the 

 expression, morphologically, of the hooked form of the proximal end of every facial bar ; 

 its orbital process is the " pedicle " or apical process (2>d). 



Here, in the bird, instead of being enclosed in the tympanic cavity, it forms its cres. 

 centic anterior wall and boundary, and to it the rim of the membrana tympani is largely 

 attached. Our ancestors called the quadrate the " tympanic " '■ ; but younger eyes have 

 beheld the true tympanic in another form : here it is seen divided into a fine chain of 

 bones, seven in all ; one of the seven, the largest, has a side duty imposed upon it, 

 namely the walling-in of the " siphonium." This tube (fig. 1, s])m) is membranous in 

 the fledgeling; but afterwards in the Cor^idse, and in many of the singing-buxls, the 

 principal tympanic is coiled upon itself, the opposite edges uniting ; thus the tube is 

 quite enringed. 



My demonstrations of these parts are from an old Carrion-Crow {Corvus corone) ; this 

 is the example mentioned by Prof. Huxley (Elem. Comp. Anat., note to p. 249) as 

 having six tympanies, as I had then informed him. 



In fig. 7 the bone attached to the jugal [j) and that behind the articulare are " sesa- 

 moids " {sd) in the " external quadrato-articular ligament ;" but the more massive bone 

 running downwards from the tympanic ring to the upper surface of the " internal 

 angular process" of the mandible is the " os siphonii" or principal tympanic. 



In fig. 8 the pneumatic passage into the lower jaw is shown, a bristle passing into 

 it ; in fig. 9 the bristle passes also through the lower third of the insheathing tympanic, 

 which is seen to be folded upon itself. Fig. 5 a is the upper or tympanic end of the 

 bone, its edges perfectly closed in, forming an oval aperture. In the Crocodile (see 

 Huxley, " On the Eepresentatives of the Malleus and Incus," Proc. Zool. Soc. May 27, 

 1869, p. 391) the siphonium carries air from the quadrate into the articulare — but in 

 the bird, from the tympanic cavity, as Nitzsch has rightly described it. 



Correlated with the compound vomer, attached to the nasal vestibule, we have, with 



' This fine old race of teleological anatomists is nearly extinct ; only Owen remains of the remnant of the 

 giants. 



