54- 



VEKTEBRATA : MAMMALIA. 



cranium, and is therefore immovable ; the lower jaw is 

 formed of two pieces only, one on each side the two in 

 some species fixed firmly together by what is called an- 



Cranium of a Dog, upper surface. Reduced in Size. 



SO, supraoccipital; IP, interparietal; Pa, parietal; Sq, squamosal; Fr, frontal; Ma, 

 malar; L, lachrymal; MX, maxilla; Na, nasal; PM*, premaxilla; ap, anterior palatine 

 foramen; io, infraorbital foramen; po/, postorbital process of frontal bone. 



chylosis and is articulated directly with the skull, with- 

 out the intervention of a bone which anatomists call the 

 quadrate bone, such as exists in Birds and Eeptiles ; and 

 the teeth are enamelled. And it may be added here that 



