THE ENDOSKELETON 



693 



l.Oc. 



Fig. 412. 



Upper view, a diagram of a bird's skull, disarticulated. 

 (After Gadow. ) Membrane bones shaded. B.Oc., basioccipital ; 

 E.Oc., exoccipital ; S.Oc., supraoccipital'; Pa., parietal ; Fr., frontal ; 

 Na., nasal ; pm., premaxilla ; M., maxilla ; Jit., jugal ; Qj., qua- 

 drato-jugal ; Qu., quadrate ; PL, palatine ; Pt., pterygoid ; pe., 

 periotic ; Sq., squamosal ; AS., alisphenoid ; B.S., basisphenoid ; O.S., 

 orbitosphenoid ; Pr.Sph., presphenoid ; vo., vomer ; iOS., interorbital 

 septum ; E., ethmoid ; Se., nasal septum ; De., dentary ; Sp ., 

 splenial ; An., angular ; SA., supra-angular ; Ar., articular ; M.K., 

 Meckel's cartilage. 



Lower views, model of developing chick-skull. A, profile view, 

 and B, hyoid apparatus, as seen from below, ang., Angulare ; b.br., 

 basibranchial ; b.hy., basihyal ; c.aud., auditory (otic) capsule; 

 c.ent., entoglossal cartilage ; c.meck., Meckel's cartilage ; coi.au., 

 auditory columella ; cor.hy., cornua of the hyoid ; dent, dentary ; 

 e.br., epibranchial, 1 ; fr, frontal ; fc.br 1 ., ceratobranchial, 1 ; max, 

 maxillary ; was, nasal ; operc, opercular ; pa, parietal ; pal, palatine ; 

 pl.a.o., anteorbital plane ; pl.s.sept., supraseptal plane ; pl.sph.l., 

 sphenolateral plane ; pr.fr., prefrontal ; pr.r.art., retroarticular 

 process; pr.tect., Processus tectalis (roof -forming) ; p.sph., para- 

 sphenoid ; pter, pterygoid ; qu, quadrate ; qu.j., quadrato-jugal ; 

 s.ang., supraangular ; sept.i.o., interorbital septum ; sq, squamosal ; 

 vom, vomer; zyg, zygomatic process. (After Gaupp.) 



