. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. Dorsal vertebra of a Whale. The lumbar vertebrae (m, Jig. 246), the posterior limit of which it is difficult to deter- mine in animals devoid of pelvis, have their spinous (a, jig. 252) and transverse processes (b) very long. The first are straight and slightly inclined backwards. As it is essential that the Cetaceans should have the posterior part of their vertebral co- lumn left free, to allow of the vigorous in- flexions of the tail required in the act of Lumbar vertebra of a Whale. swimming, none of the vertebrae are
. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. Dorsal vertebra of a Whale. The lumbar vertebrae (m, Jig. 246), the posterior limit of which it is difficult to deter- mine in animals devoid of pelvis, have their spinous (a, jig. 252) and transverse processes (b) very long. The first are straight and slightly inclined backwards. As it is essential that the Cetaceans should have the posterior part of their vertebral co- lumn left free, to allow of the vigorous in- flexions of the tail required in the act of Lumbar vertebra of a Whale. swimming, none of the vertebrae are anchy- losed together or encumbered by a union with posterior extremities, and hence there are none which can be properly termed sacral, unless we regard the sacrum as represented by the single vertebra, (n, Jig. 246,) to which, in the Dugong, the pelvic bones are suspended. The caudal vertebrae may then be considered to commence from this point. Most of these vertebrae (o, Jig. 246) are further charac- terized by the chevron bones, (p, Jigs. 246, 253,) which at first are strong and well deve- loped, but together with the other processes gradually diminish and disappear towards the extremity of the vertebral column, where the centres or bodies of the vertebrae alone appear, and present a depressed flattened form cor- responding to the horizontal position of the caudal fin, which characterises these air-breath- ing inhabitants of the ocean. Fig. 253 represents one of the anterior caudal vertebrae of the Cape W7hale: a is the spinous; b the transverse; c, r, the represen- tatives of the an- Fig. 253. terior oblique pro- cesses; p the in- feriorspmous pro- cesses, or chevron bones. To bones so lit- tle mobile, and so rudimental as the vertebrae of the neck in Cetace- ans, muscles pro- portionately de- veloped should correspond, and such in fact is the case. The cervical muscles in these animals are the same in number as in other Mammals, Caudal vertebra of a Whale. but their sho
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