Se ee 
PSL SS eM aS 
ON THE VERTEBRATE SKELETON. 337 
ligible to Cuvier. When Oken called the ‘tympanic’ a ‘cranial scapula’ he 
unduly extended the meaning of the term ‘scapula,’ and converted it froma 
specific to a generic one. The tympanic is the homotype of the scapula, 
both being modified pleurapophyses, but each has an equal claim to its proper 
or specific name indicative of their respective modifications. 
I am aware that Oken meant more than mere serial homology when he 
called the tympanic the ‘ blade-bone of the head’: it is part of the phraseology 
of the hypothesis of the head being a repetition of the whole body, &c. But 
at the time when that anatomist wrote it was not known or suspected that 
the head already possessed the scapula, and that the modified pleurapophysis 
so called, actually appertained to a segment of the skull (fig. 5, 50, 51). In 
the terms ‘femur capitis,’ ‘tibia,’ ‘fibula,’ « pes capitis,’ applied by Oken to the 
parts of the teleologically compound mandibular ramus, and in those of ‘ wlna’ 
and ‘ manus capitis, applied to the distal segments (21, 22) of the maxillary 
arch, we have not only instances of the attempt to express general relations of 
repetition or homology by special terms, but these modes of expressing the 
serial homologies of nos. 29, 30, 32, and of 21 and 22, betrays the misappre- 
ciation of the general homologies of the locomotive extremities, and their 
relations to the vertebral arches supporting them. 
To gain an insight into whatever proportion of truth may be involved in 
the ideas signified by the phrases above cited, it is necessary to determine 
the essential nature of the parts called ‘femur,’ ‘tibia,’ ‘ humerus,’ ‘ ulna,’ 
‘manus,’ ‘ pes,’ &c., or the general homology, in short, of locomotive members, 
and the attempt to master this problem has been not the least difficult part 
of the present inquiry. Cuvier has offered no opinion, nor does he appear 
to have ever troubled himself with the attempt to decipher the significa- 
tion of the locomotive members of the vertebrate animals; 7. e. of what 
parts of the primordial or pre-existing vertebrate model they are the 
modifications. 
_ Oken’s idea of the essential nature of the arms and legs is, that they are no 
other than ‘liberated ribs’: “ Freye Bewegungsorgane konnen nichts anderes 
als frey gewordene Rippen seyn *.” 
Carus, in his ingenious endeavours to gain a view of the primary homologies 
of the locomotive members, sees in their several joints repetitions of vertebral 
bodies (¢ertiar-wirbel)—vertebre of the third degree +—a resultof an ultimate 
analysis of a skeleton pushed to the extent of the term ‘ vertebra’ being made 
to signify little more than what an ordinary anatomist would call a ‘ bone.’ 
But these transcendental analyses sublimate all differences, and definite 
knowledge of a part evaporates in such unwarrantable extension of the mean- 
ing of terms. 
it has been, however, I trust, satisfactorily demonstrated that a vertebra 
is a natural group of bones, that it may be recognised as a primary division 
or segment of the endoskeleton, and that the parts of that group are definable 
and recognizable under all their teleological modifications, their essential 
relations and characters appearing through every adaptive mask. 
According to the definition of which a vertebra has seemed to me to be sus- 
‘ceptible, we recognise the centrum, the neural arch, the hemal arch, and the 
appendages diverging or radiating from the hemal arch. The centrum, 
though the basis, is not less a part of a vertebra than are the neurapophyses, 
hzmapophyses, pleurapophyses, &c.; and each of these parts is a different 
part from the other: to call all these parts ‘vertebra’ is in effect to deny 
* Lehrbuch der Natur Philosophie, p. 330, 8vo, 1843. 
t Urtheilen des Knochen und Schalengeriistes, fol. 1828. 
