SKULL OP THE ^GITHOGNATHOUS BIRDS. 279 



the outer a little the longer of the two. These processes continue long and sharp even 

 in thoroughly fledged birds (Plate LI. fig. 2). In the adult the dentary part is a 

 broadish band of bone, enlarged near its end by the coalescence with it of the descend- 

 ing crus of the nasal, but not by the maxillary, which lies behind it as in other Classes 

 of the Vertebrata. 



The palatine processes of the praemaxillaries {p.px) are now small processes lying 

 below the prsepalatal bar, at its end ; between these there is an elegant triangular 

 middle process. The angle of the dentary part is cut off transversely, and is notched 

 in the middle ; into this notch the fore end of the once styliform maxillary {op. cit. fig. 4, 

 mx) fits : it is now a short knuckle of bone. The body of the maxillary is very short, 

 and at once gives off and ends in two processes — one, the jugal (j.mx), originally very 

 long and free (op. cit.), but now coalesced with the jugal ; the other branch is the maxillo- 

 palatine {mx.p), once [op. cit.) a large curved spatula, and now a large, decurved ladle, 

 its end being wrought into a thin-walled air-cell. Above, the hinge is made by such 

 adaptation of the rostrum with the frontals that the fibres of bone running into the liga- 

 ment are extremely thin, and the bones are nearly applied by transversely squared ends. 

 In the vomer also the Tits are contrary to their relations ; for, whilst its shoulders are 

 broad, its legs are feeble and drawn near together (Plate LI. fig. 1, v). In the embryo 

 {op. cit.) the vomer is two threads of bone ; in my figure these are shown as just united 

 in front, and these threads converge backwards. In adults of the same species, 

 through difference of age, the head of the bone varies : it has no emargination at 

 first ; but this appears and increases as the bony matter creeps into the contiguous 

 nasal wall. 



The vomer is subcarinate in front, below ; and it neither shows parallel lateral divi- 

 sion, nor have I found the smallest septo-maxiUary at its angles. The septum nasi has 

 a large posterior ossicle (fig. 1, s. n), which involves the wings, or bridges, that cover 

 the nasal-nerve tract. The rest of the relatively large and deep septum is ossified con- 

 siderably above, in conjunction with the floor of the alae, in front ; but the trabecular, 

 or basal portion {tr), which is alate, remains soft, as do the turbinals and outer 

 wall. 



The ecto-ethmoid (fig. 1, p.p, e.eth) is typically Passerine: the upper part projects 

 moderately ; the pars plana is thick and spongy, and has a lateral rounded emargination, 

 a large " foot," and no appended os uncinatum. The nerve-passages above the ante- 

 orbital are perfectly distinct. I find no distinct lacrymal in the adult. 



Example 56. Skull of the Ox-eye Tit {Parus major). 



Habitat. Great Britain. 



In a young specimen of our native largest Tit the parts just described are interme- 

 diate between those of the embryo {op. cit.) and of the adult of the last species. The 



