ON THE VERTEBRATE SKELETON. 213 



the pterygoid processes laterally and upwards through the fissura orbitalis 

 superior, anterior to the great ala, and finally between the frontal and the 

 parietal bones, we trace another line, which divides the second from the 

 third vertebra " {ib. p. 7). 



" Now," says Oken, " take the ear-vertebra from a foetus of any mammal 

 or of man, place near it an immature dorsal vertebra, or the third cervical 

 of a crocodile, and compare the pieces of which they consist, their form, their 

 contents, and the outlets for the nerves. 



" According to Albinus and all anthropotomists, each vertebra of the 

 foetus consists of three distinct parts — the body and the two neurapophyses 

 (bogentheile). You have the same in the occipital bone, but more clearly 

 and more distinctly : the 'pars basilaris' is separated as the body of the ver- 

 tebra from the ' partes condyloidese,' which form the lateral parts : these 

 are still more distinct from the 'pars occipitalis' which forms the spinous 

 process : even this part is often bifid, like the spinous processes in spina 

 bifida" 



" Since then the foramen magnum is the hinder or lower opening of a 

 vertebral canal, the condyles true oblique vertebral processes, the foramen 

 lacerum an intervertebral foramen, and the crista occipitalis a spinous pro- 

 cess, proved to be such by both its position and the muscles inserted into it, — 

 since lastly the whole occipital bone in relation to its form as well as its 

 function — inclosing the cerebellum as a production of the spinal chord, — is 

 a true and in every sense characteristic vertebra, it is unnecessary to dwell 

 more diffusely on parts, the bare mention of which suffices to make their 

 nature recognizable." — ib. p. 7. 



This will serve as an example of the close observation of facts, the philo- 

 sophical appreciation of their relations and analogies, and, in a word, of the 

 spirit in which Oken determines the vertebral relations of the cranial bones 

 of the skull : and I refer to Table II. for his conclusions as to the parts of 

 the second and third cranial vertebrae. 



Reverting to the petrosal, Oken thus beautifully and clearly enunciates 

 its essential nature and homology: — "You will say I have forgotten the 

 ' pars petrosa.' No ! It seems not to belong to a vertebra, as such ; but to 

 be a 'sense-organ' (Sinnorgan), in which the vertebral- or ear-nerve loses 

 itself ; and, therefore, is as distinct an organ from a vertebral element as is 

 any other viscus (Eingeweide), or as is the eyeball itself. The (cause of) 

 delusion (as to the homology of the petrosal) lies in this, viz. that it must be 

 ossified agreeably with its nature (wesen),just as the eye must be crystallized." 



Although Oken does not in this essay formally admit a fourth vertebra 

 anterior to the ' eye-vertebra,' he recognises the vertebral structure as being 

 carried out rudimentally or evanescently, by the vomer, as the prolongation 

 of the cranio-vertebral bodies, by the lacrymal bones, as their neurapo- 

 physes, and by the nasal bones, as the spinous process. His ideas of a 

 vertebra have evidently at this period not extended beyond the ordinary 

 anthropotomical one of centrum and neural arch with its transverse, oblique, 

 and spinous processes. When he indicates (beautifully and truly) the general 

 homology of the palatine bones, as pleurapophyses, under the name of an- 

 chylosed or immoveable ribs of the head, it has reference to the transcen- 

 dental idea of the repetition in the head of all the parts of the body. Thus 

 the squamosal in mammals and the tympanic in birds represent the 'scapula' 

 of the head, and at the same time, also, the ilium. The homologue of the 

 squamosal (fig. 21, 27) in the bird is the 'humerus capitis': the malar (26) 

 and the maxillary (21) are the ' oberarm' (radius and ulna capitis) : the pre- 

 maxillary (22) is the ' manus capitis.' The segments of the hind limb are 



