276 AN ELEMENTARY TEXT-BOOK OF BIOLOGY. 



The lower jaw or mandible consists of two halves or rami, 

 each of which unites in front with its fellow in the mandibular 

 symphysis, and articulates behind by a longitudinally elongated 

 condyle with the glenoid fossa, a smooth hollow on the under side 

 of the zygomatic process of the squamosal. It is laterally flat- 

 tened and composed of an anterior horizontal part bearing sockets 

 for the lower teeth, and a posterior ascending part ending in the 

 condyle above in front of which is the coronoid process and 

 uniting with the horizontal portion in the rounded angle. 



Hyoid and First Branchial Arches. The proximal end of the 

 hyoid arch is formed by the stapes. The "hyoid apparatus" 

 consists of a small lasi-liyal imbedded in the root of the tongue, 

 and with which are connected short anterior and long posterior 

 cornua. The anterior cornua represent the hyoid arches of the 

 embryo, and are connected by ligaments with the skull, close to 

 the mastoid processes. In this region a small part of the hyoid 

 arch (tympanohijal) is fused to the skull. The posterior cornua 

 represent the first branchial arches. 



Fig. -64. ENDOSKELETOX OF RABBIT. A, Skull (jugal bone removed) ; 

 s-oc, supra-occipital ; ex-oc, ex-occipital ; c, condyle ; par, par- 

 occipital process ; s-m.f, stylo -mastoid foramen ; ty, tympanic ; per, 

 periotic ; i-p, inter-parietal ; pa, parietal ; a-s, ali-sphenoid ; sq, squa- 

 mosal ; z.s, zygomatic process of squamosal ; pt, pterygoid ; fr, frontal ; 

 or.s, orbito-sphenoid ; pr-s, pre-sphenoid ; pi, palatine; mx, maxilla; 

 , zygomatic process of ditto (with cut end); p-mx, pre-maxilla ; la, 

 lachrymal ; na, nasal ; op-f, optic foramen ; x placed at junction of 

 basi- and pre-sphenoid. A', Outside of periotic, after removal of 

 tympanic; ma, mastoid portion; m.pr, mastoid process; pr, promon- 

 tory ; f.ov, fenestra ovalis ; f.ro, fenestra rotunda. A", Auditory 

 ossicles from inside ; rn, malleus ; i, incus ; st, stapes. B, Mandible ; 

 c, condyle ; a, angle ; c.pr, coronoid process. C, Hyoid apparatus ; b, 

 body ; a.c, anterior cornu ; p.c, posterior cornu. D, Various vertebrae ; 

 1, atlas (front view); 2, axis ; 3, typical cervical (front view) ; 4, typi- 

 cal lumbar ; c, centrum ; n. s, neural spine ; t. transverse process ; a.f, 

 (in atlas), articular facet for coudyle ; a.z, prezygapophysis ; p.z, post- 

 zygapophysis ; n.c, neural canal ; v.c, vertebrarterial canal ; o.p, odon- 

 toid peg; i.l, cervical rib; ep, epiphysis ; mt, metapophysis ; an, ana- 

 pophysis. E, Hip-girdles and Sacrum. 1, 2, 3, Sacral vertebrae ; s.r, 

 sacral rib ; il, ilium ; pb, pubis ; is, ischium (reference letter placed in 

 obturator foramen) ; ac, acetabulum. F, Right tarsus ; as, astragalus ; 

 ca, calcaneum; en, centrale ; t, 1-5, tarsalia; 2-5, metatarsals ; *, 

 placed by process of met. 2, representing hallux. G, Left Scapula 

 s-sc.b, co.b, gl.b, supra-scapular, coracoid, and glenoid borders; sp, spine; 

 ac, acromion ; mtc, metacromion ; co, coracoid process ; gl, glenoid 

 cavity. H, Left Carpus r, Radiale ; i, intermedium ; w, ulnare ; en, 

 centrale; c, 1-5, carpalia ; 1-5, metacarpals. 



