THE SKIN AND SKELETON. 143 



BONES OF THE MAMMALIAN SKULL.* 



BRAIN-CASE. 



NASAL. 



NOSE. 



KTHHOID. 



FRONTAL. PARIETAL. SUPRAOCCIPITAL. 



LAC HRYMAL. SQUAMOSAL. 



ORBITOSPHENOID. EYE. ALISPHENOID. PERI- EAR. OTIC. EXOCCIPITAL. 



MALAR. TYMPANIC. 



PRESPIIEN01D. BASISPIIENOID. BASIOCCIP1TAL. 



rOXER. HYOID ARCH. 



PREMAXILLA. MAXILLA. PALATINE. PTERYGOID. 

 LOWER JAW, OR MANDIBLE. 



THE SKULL OF THE DOG. 



FIG. 108. Under surface. FIG. 109. Upper surface. FIG. 110. Longitudinal ver- 

 tical section; one-half natural size: SO, supraoccipital : ExO, exoccipital ; BO, 

 basioccipital ; IP, interparietal ; Pa, parietal ; Fr, frontal ; Sq, equamosal ; Ma, 

 malar; L, lachrymal ; MX, maxilla ; PMx, premaxilla ; Art, nasal ; SIT, maxillo- 

 tnrbinal: ET, ethmoturbinal ; ME, ossified portion of the mesethmoid ; CE, cri- 

 briform, or sieve-like, plate of the ethmoturbinal ; VO, vomer ; PS, presphenoid ; 

 OS, orbitospheuoid ; AS, alispheuoid ; BS, basisphenoid ; PI, palatine; Pt, 

 pterygoid; Per, periotic ; TIJ, tympanic bulla ; on, anterior narial aperture ; ap, 

 or apf, anterior palatine foramen ; ppf, posterior palatine foramen ; io, infra- 

 orbital foramen ; pof, postorbital process of frontal bone ; op, optic foramen ; /, 

 ephenoidal fissure ; fr, foramen rotundam, and anterior opening of alisphenoid 

 canal; as, posterior opening of alisphenoid canal ; fo, foramen ovale ; Jim, fora- 

 men lacernm medium; af, glenoid fossa; gp, postglenoid process; paf, post- 

 glenoid foramen; earn, external auditory meatus ; m, stylomastoid foramen; 

 ftp, foramen lacernm posterins ; cf, coudylar foramen ; pp, paroccipital process ; 

 oc, occipital condyle ; fm, foramen magnum ; a, angular process^ , symphysis of 

 the mandible where it unites with the left ramns ; id, inferior dental canal ; cd, 

 condyle ; cp, coronoid process ; the * indicates the part of the cranium to which 

 the condyle is articulated when the mandible is in place ; the upper border in 

 which the teeth are implanted is called alveolar ; sh, eh, ch, bh, th, hyoidean ap- 

 paratus, or os linijuce, supporting the tongue. In, the skulls of old animals, 

 there are three ridges: occipital, behind; sagittal, median, on the upper surface; 

 and superorbital, across the frontal, in the region of the eyebrows. The last is 

 highly developed in the Gorilla and other Apes. 



* In this diagram, modified from Huxley's, the italicized bones are single ; the 

 rest are double. Those in the line of the Ethmoid form the Cranio -facial Axis: 

 these, with the other sphenoids and occipitals, are developed in cartilage ; the rest 

 are membrane bones. In the Human skull, the four occipitals coalesce into one. 



