HOMOLOGIES OF THE BOXES OF THE HEAD. 75- 



The general correspondence between the bones of the head in man and animals, 

 implied in the names given to them in the foregoing table, is so well ascertained, 

 and, in most instances, so obvious, that it is unnecessaiy to say more than that 

 it is veiy generally acknowledged by comparative anatomists, and that it is chiefly 



Fig. 6i. 



mnr- 



Fig. 64. — DlAQRAMMATIC VIEW OP THE BoNES IN THE MGHT HALF OF A FcETAL. 



Skull fkom the inside. (A. T.) 



In this figure the bones have been slightly separated and displaced so as to bring the 

 whole into one view : /, frontal ; pa, parietal ; so, supra-occipital ; n, nasal ; /, lachry- 

 mal ; mn, malar ; os, orbito-sphenoid ; as, ali-sphenoid ; sq, squamosal ; zy, zygomatic ; 

 per, petro-mastoid ; to, exoccii)ital ; et, ethmoturbinal ; mx, maxilla ; mt, maxillo- 

 tiirbinal ; pi«, i)remaxil]ary ; mc, iiiesetlimoid ; r, vomer ; pi, xtalatal ; piU pterygoid ; 

 ps, presjjhenoid ; bs, basisphenoid ; ho, basioccipital ; c, bodies of 2nd, ord, and 4tli 

 cervical vertebrie ; c, odontoid process ; x, anterior arch of atlas ; s, spinous process of 

 1st, 2nd, 3rd, and 4th cervical vertebrae ; cm, ncnral or medullaiy canal ; ch, a line in- 

 dicating the position of the notochord passing through the vertebral bodies into base of 

 the cranium, hs ; ty, tympanic ring, along with ml, i, and st, displaced from its connection 

 with p>ci' ', 'nil, malleus ; c,mh, cartilage of Meckel ; mn, lower jaw or mandible ; ?', incus ; 

 St, stapes ; stJi, stylo-hyal ; c/t, cerato-hyal (lesser cornu); ih, thyro-hyal (greater cornu) ; 

 bh, basi-liyal (body of hyoid). 



on some points connected with the earliest condition, and the homological com- 

 parison of a few of the bones, that differences of opinion continue to exist. 



Besides the general evidence in favour of the homologies of these bones which 

 has been di-awn from the study of tlieir fonn, position and connections, strong 

 confirmation of these views is also obtained from theii- relations to other organs. 

 Among these, from the remarkable constancy of their relations, the passage of the 

 nerves out of the cranium is one of the most important. Thus, the nerves 



