234 



GENERAL ORNITHOLOGY 



PART n 



the ear, bounded pretty sharply by the squamosal and exoccipital 

 rim, sloping with less distinction in front toward the orbital cavity. 

 In this auditory hollow may be seen several openings : the meatus 



or proper ear- 



through 

 which, in one direc- 

 tion, a bristle may 

 be passed to emerge 

 at or near the 

 middle line of the 

 base of the skull, 

 about the root of 

 the basisphenoidal 

 rostrum. Such a 

 passage is through 

 the first visceral 

 cleft of the early 

 embryo, modified 

 into meatus audi- 

 torius and Eusta- 

 chian tube, which 

 latter communicates 

 with the back part 

 of the mouth. Be- 

 sides the other ear- 

 passages proper, 

 may be found other 

 openings of air- 

 passages leading 

 into the interior 

 diploic tissue of 

 bones of the skull. 



Pig. 71.— Ripe chick's skull, in profile, x 3 diameters ; after and especially into 



Parker, px, premaxiUary ; aln, alinasal cartilage; en, septo- i-i i • i. 



nasal ; n, nasal bone ; i, lacrymal ; pe, perpendicular plate of tUe lOWCr ]aW-D0ne. 



ethmoid, as in Fig. YO ; ps, presphenoidal region; as, alisphe- TTio ooy yiorfo aro 



noid ; /, frontal ; p, parietal ; sq, squamosal ; so, superoccipital ; ^'^'^ e<ll-pd,ltb dlB 



eo, exoccipital ; oc, occipital condyle ; st, the cross-like object, immensely deve- 



the stapes, whose foot fits fenestra ovalis, see Fig. 83 ; q, quad- -, j . -, 



rate ; pg, pterygoid ; qj, quadratojugal ; j, jugal ; pa, palatine ; loped m OWlS, in 



mx, maxillary. In the mandible: d, dentary ; sn, surangular ; ->,„_,, ono^ioo nf 



a, angular ; ar, articular ; iap, internal angular process ; pap, nidliy specieh Ui 



posterior angular process. 2, optic foramen ; 5, foramen ovale, which thev are un- 



for inferior divisions of the 6th nerve. (Compare Fig. 70.) . ■' 



symmetrical, that 

 is, not sized and shaped alike- on right and left sides of the head. 



The Sphenoid. (Gr. (T<jyriv, sphen, a wedge ; eiSos, eidos, form ; 

 Figs. 62, 70, 71) is a compound bone, not easy to understand as it 

 occurs in birds, as much of it is hidden from the outside, some of 

 it is very slightly developed, and all of it is completely consolidated 



