THE SKIN AND SKELETON 



351 



BONES OF THE MAMMALIAN SKULL* 



BRAIN CASE 



NASAL. 



NOSE. 



ETHMOID. 



FRONTAL. PARIETAL. SUPRAOCCIPITAL. 



LAC HRYMAL. SQUAMOSAL. 



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



MALAR. TYMPANIC. . 



PRESPHENOID. BASISPHENOID. BASIOCCIPITAL. 



VOMER. 



PREMAXILLA. MAXILLA. PALATINE. PTERYGO1D. 

 LOWER JAW, OR MANDIBLE. 



HYOID ARCH. 



THE SKULL OF THE DOG 



FIG. 305. Under surface. FIG. 306. Upper surface. FIG. 307. Longitudinal ver- 

 tical section; one half natural size. S%)f supraoccmital ; .fi'.j^^exoccipital; BO, 

 basioccipital; IP, interparietal; Pa, parietal; FV\ frontal; Sff* squamosal ; Ma, 

 malar; L, lachrymal; Afcrf / maxi\\a.; PMx, premaxilla; Na, nasal; MT, maxillo- 

 turbinal; ET, ethmoturbinal; ME, ossified portion of the mesethmpid; CE, cri- 

 briform, or sievelike, plate of the ethmoturbinal; l?), vomer; &S, presphenoid; 

 OS, orbitosphenoid ; ;4J>j"Sfisphenoid ; Eg, basisphenoid; PI, palatine; PPj ptery- 

 goid; Per, periotic; Ty, tympanic bulla; an, anterior narial aperture; ap, or apf, 

 anterior palatine foramen; ppf, posterior palatine foramen; io, infraorbital foramen; 

 J0/f'postorb\ta.\ process of frontal bone ; ty, optic foramen; sf, sphenoidal fissure; 

 fr, foramen rotundum, and anterior opening of alisphenoid canal; ^/"posterior 

 opening of alisphenoid canal; fa, foramen ovale; flm, foramen lacertim medium; 

 gf, glenoid fossa; jtf', postglenoid process; Plgf, postglenoid foramen; earn, external 

 auditory meatus; sm, stylomastoid foramen; flp, foramen lacerum posterius; cf, 

 condylar foramen; pj/, paroccipital process; otf, occipital condyle; Jfrrt, foramen 

 magnum; a, angular process; s, symphysis of the mandible where it unites with the 

 left ramus; id, inferior dental canal; cd, condyle; cp, coronoid procass ; z indi- 

 cates 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 apparatus, or os lingua, 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 eye- 

 brows. 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 



