. On the anatomy of vertebrates. Vertebrates; Anatomy, Comparative; 1866. 28 ANATOMY OF VERTEBRATES. 18. Cranial sogmcii^or vertoljia throughout the vertebrate series; and some parts, usually, exo- genous, are autogenous in a few instances. The vertebral elements are, the centrum c, the neurapophyses n ; the neural spine ns, the pleurapophyses pi, the Ivccmapo- physes /(, and the haimal spine hs. The exogenous parts are the diapophysis d, the parapophysis;), the zygapophysis r,' the ana- popliysis «,^ the metapophysis m,^ the hypa- jiophysis, fig. 17, y,"* and the epapophysis, fig. 17, e.
. On the anatomy of vertebrates. Vertebrates; Anatomy, Comparative; 1866. 28 ANATOMY OF VERTEBRATES. 18. Cranial sogmcii^or vertoljia throughout the vertebrate series; and some parts, usually, exo- genous, are autogenous in a few instances. The vertebral elements are, the centrum c, the neurapophyses n ; the neural spine ns, the pleurapophyses pi, the Ivccmapo- physes /(, and the haimal spine hs. The exogenous parts are the diapophysis d, the parapophysis;), the zygapophysis r,' the ana- popliysis «,^ the metapophysis m,^ the hypa- jiophysis, fig. 17, y,"* and the epapophysis, fig. 17, e.^ Of the autogenous parts, the neural spine is most commonly exogenous; of the exogenous parts, the parajiophyses, diapophyses, and hypapophyses, are sometimes autogenous. Vertebra3 are suliject to many and great modifications—e. g. as to the number of the elements retained in tlieir composition, as to the form and pro2:)ortion of the elements, and e^'en as to the relative position of the elements ; but the latter modification is never carried to such a degree as to obscure the general pattern or type of the bony segment. Sometimes, as in the example, fig. 18, of the third segment of the human skeleton, tlie neural arch, N, is much expanded, the hcBmal one, ii, is contracted; and, in the expanded neural arch, the autogenous diapophyses, d d, are wedged between the neura- pophyses, n, and the enormously expanded neural spine, ns. IMore 19 commonly, as in the example from the thorax, fin-. 19, the ]ia3mal arch, /;.«, is much expanded, the neural one n, contracted; and the parapophysis is re]>re- sented somethnes by tlie exogenous growth from the centrum, commonly by that, p, from the ril) pi. Sometimes, again, as is exemplified in the neck of the bird, fig. 20, and tlie tail of the Crocodile, both neural and luvmal arches arc alike contracted, the pleurapophyses, /)/, being excluded from the latter, and standing out as continuations of the confluent diapophyses and parapop
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