SKELETON OF MAMIKALS. 
7 
few notes and explanatory figures are given before coming to 
the proper subject of this Guide. 
The skeleton of a Mammal consists of two portions : one 
containing the bones belonging to the central axis of the body, 
viz. the skull, backbone, ribs, and breast-bone ; and a second 
portion, comprising those which form the limbs, and the girdles 
of bone by which the latter are attached to the backbone. 
Fig. 2. 
The Skull of a Fog, divided down the middle line to show the 
internal structure. 
angular ; an, nostril ; as, alisphenoid ; ho, basioccipital ; hs, hasisphenoid ; 
c, canine teeth; cd, condyle of lower jaw; ce, cribriform plate; cp, 
coronoid process ; ex'o, exoccipital ; fr, frontal ; h, hyoid ; incisor 
teeth ; id, inferior dental canal ; ip, interparietal '>n, molar teeth ; 
me, mesethmoid ; mx, maxilla ; na, nasal ; os, orbitosphenoid ; pa, 
parietal ; per, periotic ; pi, palatine ; pm, premolar teeth ; prnx, pre- 
maxilla ; presphenoid ; pt, pterygoid ; s, union of two halves of 
lower jaw; so, supraoccipital ; t, turbinal; vo, vomer. (^From Sir 
TV. H. Flower.) 
The skull is the portion of the axial skeleton by far the most 
important to the systematic naturalist, who bases in great part 
his classification of Mammals on the variations presented by the 
