THE ANATOMY OF BIRDS. — OSTEOLOGY. 



159 



thickened by the uiiderflooriiii; of the parasphenoid (fig. 70, rhs). The rostrum often hears 

 on each side a hasipterijgoid process {apt), — a smooth facet with whicli the pterygoid artic- 

 ulates. These processes may he very 

 stroni;, and far Ijaeli on tlie hasisphenoid 

 body, when the pterygoids articuhite with 

 theu'i near their own posterior ends, as 

 in the struthious birds and tinamous (fig. 

 75, bfj:)) ; or they may be further along 

 on the rostrum, and the pterygoids then 

 articulate near or at their fore-ends. The 

 rostrum may he produced far forward, 

 beyond the maxUlo-palatines and vomer 

 even, as in an ostrich ; or it may bear the 

 vomer at its end ; or may be embraced 

 by forks of the vomer ; the palatines may 

 glide along it, or be remote from it on 

 either side. In any event, whatovei' its 

 production, whatever part may be eth- 

 mf)idal, or basisphenoidal, or parasphe- 

 noidal thickening, pterygo-faceting, etc., 

 this " beak " of the hasisphenoid is 

 always in the axis of the base of the 

 skull, and at the bottom of the inter- 

 orbital plate ; it may be horizontal, or 

 obliquely ascending furward; and the 

 variety of its relations witli the pterygo- 

 palatine and V(nneriuo mechanism fur- 

 nishes important zoological characters, 

 as we shall see wlien we come to treat 

 of palatal structure particularly. Just at 

 the base of tire beak, where it widens 

 into the main body of tlie bone, may 

 commonly be seen, coming from between 



Fig. 71 — Ripe < liK k s skull, in profile, X 3 diameters; after 



Parker, pv^ premixillar) ahi, ali-nasal cartilage ; en, septo- 



nas.nl; n, nasal bnne ; /, lacrynial; /jc, perpendicular plate of 



etlimoid, as in tig. 70; ps, presplienoitlal region; «.<.■, alisplie- 



the splienoidal body and the lip of the noid ;/, frontal ; p, parietal ; sty, squamosal ; so, superoccipital; 



v..,^.;+^...v^^,^.ii ,,«..i^„fl„ ■„:..™ +1 ^ -G <^"> exoccipital: oc, occipital condyle: st. the cross-like object, 



basitemporal undertlooring, the orihces t, , , <■ ^ i» ,- , ,' « oo / 



^ _ ^' tlie stai)es, wliose foot iits fenestra ovalis, see ng. 83; (7, quau- 



of the eustachian tubes, and often also rate; /13, pterygoid; cjj, quadrat-o-jugal; ,y,jugal; p^., palatine; 



the anterior ends of the carotid canal, "^.maxillary. In the mandible: rf, .lentary; s«. surangular; 



a, angular; ar, articular; tap, internal angular process ; 2Jap, 



[fa bristle, passed into a qnestionable posterior angular process. 2, optic foramen; .5, foramen ovale, 



foramen liere, comes out of the ear, it to inferior divisions of the Stlinerve. (Compare fig. 70.) 



has gone through the eustacliian tube : if it comes out below the ear, on the floor of the skull, 

 outside, it has run in the carotid canal. Tlie extent of the alisphenoids (figs. 70, 71, fs-s) can- 

 not be determined in old skulls. They lie at the back lower border of the orbital cavity, clos- 

 ing in most of the brain box that is not foreclosed by the frontal bone. You will always find 

 at the back of the orbit, close to the mid-line, and rather low down, the very lai-ge optic fora- 

 mina (any figs., 2) ; alisphenoid should not extend in front of these orifices. A little below and 

 behind the optic foramina, and much more laterally, not far from the quadrate itself, is a con- 

 siderable foramen, quite constant, for transmission of the inferior divisions of the fiftli {trigeminal 

 or trifacial) nerve. This is the foramen ovale (any figs., 5) ; it is either m the alisphenoid, or 

 between that bone and the proiitfc ; it must not be mistaken for one of the several smaller lioles, 

 usually seen close about the optic foramen, which transmit the nerves (oculo-motor, pathetic. 



