158 



GENERAL ORNITHOLOGY. 



sloping with less distinction in front toward the orhital cavity. In this auditory hollow may he 

 seen several openings: the meatus or proper ear-passage, through which, in one direction, a 



bristle may bo passed to emerge at or near 

 the middle line of the base of the skull, 

 about the root of the basisphenoidal ros- 

 trum. Such a passage is through the first 

 visceral cleft of the early embryo, modi- 

 fied into ■meatus atiditoritis and eiistacldan 

 tube, which latter communicates with the 

 back part i>f the mouth. Besides the other 

 ear-passages proper, may be found other 

 openings of air-passages leading into the 

 interior diploic tissue of bones of tlie 

 slcull, and ("specially into the lower jaw 

 bone. The ear-parts are immensely de- 

 veloped in owls, in many species of 

 which they are unsymmetrical, that is, 

 not sized and shaped alike on right and 

 left sides of the head. 



The Sphenoid (Gr. <Tciii)v, sphen, a 

 wedge ; ei'Sot, eidos, form ; tigs. 02, 70, 

 71) is a cnmpouud bone, not easy to un- 

 derstand 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 conscdidated with surround- 

 ing bones in the adult. It is wedged 

 into the very midst of the cranial bones 

 proper, with its body in the middle line 



Fig. 70. — Kipe chick's skull, longitudinal section, viewed below, next in front of tlie basioceipital, 

 insule. X 3 .liameters; after Parker. In the mandible. are seen : ,„jj i,g „.;,., ,j,p.jj ^„j ^■^^^.^^^ ^jj^ j^^ ,,j^, 

 m/j, remains of meckelian rod; f/. dentary bone; .-j;), siilenial ; . '? 



<x, angular i .«!. surangular; ar. articular; ja^, internal articu- orbital cavity. A sphenoid consists es- 

 I.ar process; pay), roste.i.,r articular process. In the skull : ;«!, sentiaUy of "the basisphenoid, or main 

 tue or;ginal prenasal cartilage, upon which is mouUlea the pre- . ^ 



maxillary, /jj:. with its nasal process, i?j0.r, ami dentary process, P'^l'*' <-">r the boiie (fig. 02); the aJisijjhe- 

 (}px ; ST?, septo-nasal cartilage, in which is seen nn, nasal nerve; noids or " wiut^s " ou either side Tfi^^s 70 

 ntb, nasal turbinal ; the reference line crosses the cranio-facial r-i -. i ^ ' ^ '^ * ' 



f^uture, the face parts and cranial parts being nearly separated ' ■■ t '^■'^) j ^Ik' ubsoure presphenoid, {ps) in 

 here by the nick seen in the original cartilaginous plate; eth, the luidiUe hue ill front of and above the 

 ethmoid ; ^^c, perpendicular plate of ethmoid, which will spreads • i i i i ii ? • 



nearly throngliout the dotted cartilaginous tract in which it lies, "''*"^ ^^*^»dy ; and the small OVOlto-Sphc- 

 to form nearly all the interorbital sex>tuni ; transverse thicken- noids. which are iu fact the win^^S of tli*' 

 ing (in some birds) below the reference line eth will form the , • i n^'i i j • 



pre-frontal, or orbito-nasal septum ; iof, inter-orbital foramen ; ri'<'^pIienoid. 1 lie body is usually covered 

 7w. pre-sphenoidal region, just above which is the orhito-sphe- in by the undertioorini; of the basitem- 

 iioidal region ; 2, oj^tic foramen ; as. alisj'hennid, with ,5, foramen 

 for divisions of the 5th( trifacial) nerve;./', frontal; sq, squamosal ; 

 JO, parietal; ,';o, superoccipital ; asc, anterior semicircular canal ; 

 sc, a sinus (venous canal); c;^. epiotic; -'o, exoccipital; 07), opis- 

 thotic ; po, proiitic, with 7, meatus auditorius interuus, for en- 

 trance of 7th nervo ; 8, foramen for vagus nerve ; bo, basioceipi- 

 tal ; bt, basitemporal ; ic. canal (in original pituitary space ; 

 fig. 66 ic) by which carotid artery enters brain cavity ; op, basi- 

 pterygoid process; ap to rbii, rostrum of the skull, being the central axis tif the base of the skull ; 



parasphenoid bone undertlooring the basisphenoid and future ,„\^^. +1^^ ,>-,,r.^, +1^.., ■] 1 * j.\ • c • 

 ' * '^ * witn ttie mcsL'tnmoid jilate the interior 



])oral ; it is a iiat triangular plate, pro- 

 duced more <}y less forward iu the middle 

 line as the hasisphomidal i^ostrum, or 

 beak of the skull. This rostnuti is ;\ii 

 important thing. It forms, in fact, the 



perpendicular plate of ethmoid. (The scaffolding cf the upper 

 Jaw not shown, excepting pz, &c.) 



border of the interorbital septum, usually 



