Definitions

from Wiktionary, Creative Commons Attribution/Share-Alike License.

  • proper noun zoology, obsolete The lowest group of Vertebrata, including the amphioxus, in which no skull exists.

Etymologies

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Examples

  • Opposed to the Acrania is the second division of the vertebrates, which comprises all the other members of the stem, from the fishes up to man.

    The Evolution of Man — Volume 2 Ernst Heinrich Philipp August Haeckel 1876

  • In the Acrania and Cyclostomes and the earlier fishes we can scarcely distinguish a real stomach; it is represented merely by the short piece from the branchial to the hepatic gut.

    The Evolution of Man — Volume 2 Ernst Heinrich Philipp August Haeckel 1876

  • In the alimentary apparatus there are the thymus-gland and the thyroid gland, the seat of goitre and the relic of a ciliated groove that the Tunicates and Acrania still have in the gill-pannier; there is also the vermiform appendix to the caecum.

    The Evolution of Man — Volume 2 Ernst Heinrich Philipp August Haeckel 1876

  • In the Cyclostoma -- a stage above the Acrania -- the fore end of the cylindrical medullary tube begins early to expand into a pear-shaped vesicle; this is the first outline of an independent brain.

    The Evolution of Man — Volume 2 Ernst Heinrich Philipp August Haeckel 1876

  • The Craniota descend directly from the Acrania, and these from the primitive Chordonia.

    The Evolution of Man — Volume 2 Ernst Heinrich Philipp August Haeckel 1876

  • There is no trace of these pairs of limbs in the Acrania and

    The Evolution of Man — Volume 2 Ernst Heinrich Philipp August Haeckel 1876

  • The Amphioxus is the only surviving representative of the older and lower section, the Acrania

    The Evolution of Man — Volume 2 Ernst Heinrich Philipp August Haeckel 1876

  • The lowest and earliest Vertebrates, the Acrania and

    The Evolution of Man — Volume 2 Ernst Heinrich Philipp August Haeckel 1876

  • Acrania (Amphioxus) for the phylogeny of the Vertebrate stem.

    The Evolution of Man — Volume 2 Ernst Heinrich Philipp August Haeckel 1876

  • These important parts are wholly wanting in the two lowest classes of Vertebrates, the Acrania and Cyclostoma.

    The Evolution of Man — Volume 2 Ernst Heinrich Philipp August Haeckel 1876

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