Detailed abstracts of papers on 1.- The morphological relations of the nervous systems in the annulose and vertebrate types of organization. 2.- The morphological constitution of the skeleton of the vertebrate head. 3.- The morphological constitution of limbs : communicated to the Cheltenham meeting of the British Association, August 1856 / by Professor Goodsir.

  • Goodsir, John, 1814-1867.
Date:
[1857]
Catalogue details

Licence: Public Domain Mark

Credit: Detailed abstracts of papers on 1.- The morphological relations of the nervous systems in the annulose and vertebrate types of organization. 2.- The morphological constitution of the skeleton of the vertebrate head. 3.- The morphological constitution of limbs : communicated to the Cheltenham meeting of the British Association, August 1856 / by Professor Goodsir. Source: Wellcome Collection.

Provider: This material has been provided by The University of Glasgow Library. The original may be consulted at The University of Glasgow Library.

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    osseous Fishes. These branchial actinapophyses also exhibit that jointed or multiarticulate structure so generally presented by the rays of the mesial and bilateral fins. This leads me to observe, that I have not been able to satisfy myself of the truth of the doctrine at present generally held, that the inter-spinous bones and rays of the mesial tins belong to the dermo-skeleton. I admit that, in certain instances, tliese fins present more or less dermal bone in their composition; but I cannot see how fin-rays, from which the skin and sub-cutaneous texture may be stripped, can be considered as portions of the dermo-skeleton. These rays can scarcely, I conceive, be referred to the dermo-skeleton in the cartilaginous Fishes; and as the rays of the bilateral fins resemble those of the mesial in their histological as well as in their general relations, they ought to be placed in the same category. The rays of the mesial, as well as of the bilateral fins cannot, therefore, in my opinion, be consistently excluded from that portion of the sclerome usually denominated neuro- or endo-skeleton ; but like other elements of the endo-skeleton which approach the dermal sclerous fibrous lamina, they may coalesce with dermal bone. I have been led to consider the inter-spinous bones and mesial fin-rays as actinapophyseal elements. With reference to the mesial position and characters of these bones, I would remark, that it appears to me to be quite permissible, on morphological grounds, to look upon each inter- spinous bone, with its corresponding fin-ray, as consisting of a right and left actinapophysis mesially united,^—that is, to consider the right and left halves of which they consist in the young fish as fundamental elements of opposite sides of the body. This view of the actinapophyseal character of the bones of the mesial fins appears to be supported by the occurrence of double anal and caudal fins in monstrous fishes, and also by the so- called uroliyal bone. The relations of this bone appear to me to indicate that it is not referable to the basohyal elements of the arch, but to the actinapopliyseal. I recognise it as consisting of two of these elements fused together at the mesial plane. I am further sujDported in the view which I take of the actinapophyseal character of the inter-spinous bones and mesial fin-rays, by the well- known and hitherto unexplained antero-posterior duplicity which they exhibit in certain fishes. In the Pleuronectidse, for instance, the inter- spinous bones are attached in pairs, one bone in front and another be- hind each spinous process. In these instances 1 conceive we have ex- amples of mesial anterior and posterior actinapophyses in each sclero- tome. The corresponding fin-rays are, it is true, alternate, but this does not atfect the general principle, when we keep in view the remarkable antero-posterior movements of certain elements of the sclerome discovered by Remak in the embryo, and the highly important observations of Pro- fessor Owen with reference to the alternations of some of the elements of the spine in certain Eeptiles and Birds,—alternations undoubtedly re- ferable to movements of the kind discovered by Remak. In the head actinapophyseal elements are generally bar-like, or more or less flattened from without inwards. From the peculiar forms assumed by these elements in the head, an anterior actinopophj^sis of one sclero- tome may meet a posterior one from the sclerotome in front, so as to form together a bar-like or flattened bridge, or buttress, between the two. These bridge-like connections of neighbouring sclerotomes are not un- frequently completed by the fibrous basis of tlie sclerome. In Birds, and the typical Lacertians, indeed, in which the actinapophyseal elements exhibit remarkable adaptations, the fibrous matrix in which tliey are imbedded, and by which they are connected, forms an essential feature of their arrangement.