File:On the anatomy of vertebrates (electronic resource) (1866) (14775360463).jpg

Identifier: b20416039_001 (find matches)
Title: On the anatomy of vertebrates (electronic resource)
Year: 1866 (1860s)
Authors: Owen, Richard, 1804-1892
Subjects: Anatomy, Comparative Vertebrates Fishes Reptiles Mammals Birds
Publisher: London : Longmans, Green
Contributing Library: Wellcome Library
Digitizing Sponsor: Wellcome Library

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-appears as the true inferior transverse process is increased. Theside of the neural arch is perforated for the nerve, and that of thehaemal arch for the blood-vessel. The anterior abdominal vertebra of the Tetrodon arefirmly clamped to-gether by the para-pophyses. A vegetative same-ness of form prevailsin fishes throughoutthe vertebral columnof the trunk, fig. 34,which is made up ofonly two kinds of ver-tebra?, characterisedby the direction ofthe parapophyses, p:these in the abdomi-nal region are lateral,usually stand out andsupport ribs : but inthe caudal regionbend down to form,either by direct co-alescence or by theribs that continue tobe attached to themin a vertical position,the haemal arch. The atlas is usu-ally distinguished bysome modification ofthe anterior articularend of the centrum,by the persistentsuture of the neuralarch, or by the ab-sence or detachmentof its pleurapophy-ses. Peculiar pro-cesses are sometimes Skeleton of the Haddock (Gadus ceglefinus) Sent off from the
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ANATOMY OF VERTEBRATES. 41 under part of the centrum, as, e. g. the two which articulate withthe basioccipital in the Arapaima gigas. As the centrum of theatlas retains its normal relations to the other elements, and theordinary mode of articulation with the body of the second verte-bra, this shows no 6 odontoid process in fishes. The number of vertebra? varies greatly in the different osseousfishes: the Plectognathi (Diodon, Tetrodon) have the fewest andlargest: the apodal fishes (Eels, Gymnotes) have themost and smallest, in proportion to their size. It is noteasy to determine the precise number, on account of thecoalescence of some of the vertebra?, or at least of theircentral elements, in particular parts of the column. In-stances of anchylosis of some of the anterior vertebrae,analogous to that noticed in the cartilaginous Sturgeons,Chima?ra?, Rhinobates, and some Sharks, occur alsoamongst the osseous fishes, as in many Siluroid and Cy-prinoid species, in Loricaria and Dactylopte

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