. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. 636 SKELETON. vertebrae of v,fig, 457., produce thecostae a b of greater dimensions than ordinary, these segments of the spinal axis are but resembling somewhat more completely the thoracic costo- vertebral archetypes (such as 8, c, d, of B, fig- 457.) ? Whenever, therefore, the sixth or seventh cervical vertebra produces the cervical ribs, I may interpret the occurrence of this " ano- malous " fact in this way, viz. that a greatei proportional of the archetype costo-vertebral quantity (such as 8, c, d, of 8,^.
. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. 636 SKELETON. vertebrae of v,fig, 457., produce thecostae a b of greater dimensions than ordinary, these segments of the spinal axis are but resembling somewhat more completely the thoracic costo- vertebral archetypes (such as 8, c, d, of B, fig- 457.) ? Whenever, therefore, the sixth or seventh cervical vertebra produces the cervical ribs, I may interpret the occurrence of this " ano- malous " fact in this way, viz. that a greatei proportional of the archetype costo-vertebral quantity (such as 8, c, d, of 8,^.457.) re- mains to the sixth and seventh spinal segment than is generally the rule. Cervical vertebrae, therefore, whether with or without the plus cervical ribs, are still the proportionals of full thoracic costo-vertebral forms ; and the number of cervical vertebras simply depends upon the number and degree of metamor- phosis to which thoracic costo-vertebral forms have been subjected. When the cervix de- velops seven vertebrae of those proportions, such as we ordinarily find in the mammal body (A, Jig. 456.), all we can say of it is, that seven thoracic archetypes have suffered metamorphosis of the ribs to the cervical degree ; and when the mammal cervix ex- hibits only five or six vertebrae of cervical degree (e,fig. 457.), this occurs by reason of the fact that the seventh vertebra of B is not metamorphosed to cervical degree, but still retains a large proportional of the rib (b). When the mammal cervix (\, 457., or u, jig. 456.) produces nine cervical vertebra?, then the simple interpretation is, that nine quantities, equal to those of the thorax, and which I have represented in dotted outline, have had the original plus costo-sternal quan- tity subtracted from them. PROP. XXV. The presence of cervical ribs subtracts from the number of cervical vertebra:, and adds to the number of thoracic archetypes. —Whenever cervical ribs (a, b of B,fig. 457. and 458.) are prod
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