vi .] GENERAL VIE W OF INTERNAL SKELE TON. 2 1 7 



" tubercles." Now, if each transverse process represents a rib, 

 we have here a slightly bifurcating rib. But this, as we have 

 seen, is a condition which plainly obtains in certain Batra- 

 chians, where the rib not only bifurcates proximally, but also 

 distally. 



4. Secondly, as to the question above suggested respecting 

 the " odontoid process " in man. 



It has been seen how in many animals we have a distinct 

 " odontoid " bone instead of an odontoid process interposed 

 between the axis and the atlas ; but we have nowhere observed 

 a fully developed centrum of the atlas co-existing with such 

 an odontoid bone. 



This fact indicates, what is no doubt the case, that the 

 " odontoid process " is the true centrum of the atlas, united, 

 not with the rest of its own vertebra, but xvith the centrum of 

 the axis. 



What, then, is the nature of that transverse bar of bone 

 belonging to the atlas, and passing, in man, in front of and 

 articulating with the odontoid process ? It is probably hypa- 

 pophysial in its nature, as wedge-like hypapophysial ossicles 

 are often developed between the adjacent margins of verte- 

 brae on their ventral aspect, as e.g. beneath the lumbar ver- 

 tebras of the Mole. It may, howWer^ be an ossification of 

 part of an intervertebral body. 



FIG. i06. ATLAS AND Axis VERTEBRAE OF A CHELOXIAN REPTILE. 



hy, hypapophysis of atlas ; t, transverse process ; z, prezygapophysis ; z , post- ' 

 zygapophysis ; s, neural spine ; hy', odontoid bone ; hy", hypapophysis of 

 true centrum of axis. 



{From the College of Surgeons' Mriseiim. ) 



Thus harmony and unity become manifested by means of 

 a general study of anatomy, which would escape us did we 

 investigate the human structure alone. 



5. In considering the most general relations of the human 

 skeleton it will be convenient to imagine the backbone 

 placed horizontally, with the limbs descending at right angles 

 from it, such being the position of the backbone in the great 

 majority of Vertebrates. 



