ON THE VERTEBRATE SKELETON. 243 
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 ” (7b. 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 condyloidez,’ 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” + 
ey 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.”—2b. 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 Taste II. for his conclusions as to the parts of 
the second and third cranial vertebre. 
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 
earried 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- 
ehylosed 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 
