Biological Notes

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    THE PRIMARY ELEMENTS OF THE SKULL.—At a recent meeting of the Cambridge Philosophical Society Mr. Bettany brought forward some of the ideas resulting from Prof. Barker's most recent researches, which will be embodied in a forthcoming work on the “Morphology of the Skull,” by Messrs. Parker and Bettany. A fundamental point in researches of this kind appears to be the question what are axial and appendicular elements in the skull. For some years past Profs. Huxley and Faiker have regarded the primary rods or trabeculæ occupying the base of the forepart of the skull as being the foremost of the series of facial or visceral arches (mandibular, branchial, and the like). In several types, although these trabeculæ lie in the true base of the cranium, they are at an early stage more or less parallel with the visceral arches; and certain nerve-relations appeared to show a close similarity between them. But Mr. Parker now believes their facial nature cannot be maintained. They arise in tissue immediately beneath the brain cavity as the vertebræ arise beneath the spinal canal; the temporary flexure of the fore-part of the skull does not make this tissue other than axial. Every relation of the trabeculæ proper is to the nervous centres, and cartilaginous growths continuous with them bound the cranium laterally just like the Jateral occipital or vertebral regions. Mr. Bettany also directed attention to the nasal, prenasal, and antorbital regions of the skull as probably showing rudiments of true appendicular parts in the anterior regions of the head. In the discussion which followed, Prof. Humphry cordially welcomed this rehabilitation of the trabeculæ, having never been able to agree with Prof. Huxley that they were facial in their origin. He could not doubt that the bones formed in them, the basisphenoid and presphenoid, were axial in character. He thought that further research would but demonstrate more clearly the vertebral or segmental theory of the skull.—Mr. Balfour thought research was not yet sufficiently advanced for a true estimate of the skull to be formed. Although the trabeculæ might be morphological continuations of the basal cartilages in the hinder part of the skull, yet the greater part of the vertebræ and part of the base of the skull, arose from an unpaired cartilaginous mass surrounding the notochord, while no such element existed in the anterior part of the skull. It appeared very possible that the lateral parts of the cranial floor behind were really equivalent to the base of the cartilages which formed the vertebral arches, and thus the trabeculæ might similarly be regarded as only the basal parts of the continuous lateral wall of the skull.

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    Biological Notes . Nature 15, 127 (1876) doi:10.1038/015127a0

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