THE THEORY OF THE VERTEBRATE SKULL. 283 



" If there are three vertebral bodies in the brain-ease, there 

 must be as many vertebral arches. These are to be sought 

 out and demonstrated. 



" You see the sphenoid separated into two vertebrae : through 

 the first one pass the optic nerves, through the hinder the 

 nerves of the jaws (par trigeminum). I term the former the 

 Eye vertebra, the latter the Jaiv vertebra. Against this last 

 abuts the basilar process of the occipital bone with the r petrous 

 bone. The two form one whole. As the optic nerve traverses 

 the Eye vertebra, and the jaw nerve the Jaw vertebra, so the 

 hindermost vertebra is related to the auditory nerve. I there- 

 fore term it the Ear vertebra. Again, this is the first cephalic ver- 

 tebra ; the precedent, the second ; and the eye vertebra, the third. 



" It has given me unspeakable trouble to make out whether 

 the petrous bone belongs to the first or to the second cephalic 

 vertebra. Before I had taken into account the relations of 

 the nerves, vessels, and muscles, my decision was based only 

 upon the structure of the skulls of Birds, Lizards, and Chelonia ; 

 but now I have fortified it by a multitude of concurrent argu- 

 ments, of which I will state only a few in this place. 



" You will have observed, in fact, that each of the two anterior 

 vertebrae has appropriated a sense. (As the jaws end in the 

 lips, I reckon them also among the [organs of] sense, and I 

 shall demonstrate that they are so, and how they are so.) Now, 

 if the petrous bones belonged to the jaw vertebra, one vertebra 

 would give off nerves to the sensory organs, while the first 

 vertebra would be sent empty away. True, it transmits nerves 

 to the tongue, but these are variable ; and it will be shown in 

 the sequel that neither tongue nor nose have, or can have, a 

 proper vertebra. Lastly, in Lizards, the auditory apparatus lies 

 distinctly in the occipital bone. 



" The cephalic vertebras are, therefore, sensory vertebras, and 

 only exist in correspondence with the [cephalic] senses. (The 

 tongue and the nose are trunk senses, of which presently.) 

 Vertebral divisions and cephalic sensory nerves go parallel 

 with one another. Bones are the earthly, hardened nervous 

 system ; nerves are the spiritual, soft, osseous system — con- 

 tinens and contentum. 



