vertebra, though hardly at all marked, is nevertheless really present and developed from a bony centre of its own, as in other mammals. The dorsal and lumbar vertebrae are, of course, to be distinguished by the presence of ribs attached to the former; but as there is only a rudimentary pelvis, not attached to the vertebral column, no sacral region can be detected. The caudal vertebrae are to be recognised by the 
-shaped chevron bones below.
Fig. 186.—Section through middle line of united cervical vertebrae of Greenland Right Whale (Balaena mysticetus). × 1⁄9. a, Articular surface for occipital condyle; e, epiphysis on posterior end of body of seventh cervical vertebra; sn, foramen in arch of atlas for first spinal nerve; 1, arch of atlas; 2, 3, 4, 5, 6, conjoined arches of the axis and four following vertebrae; 7, arch of seventh vertebra. (From Flower's Osteology.)
Fig. 187.—A, Sternum of Greenland Right Whale (Balaena mysticetus). × 1⁄15. B, Sternum of Common Rorqual or Fin Whale (Balaenoptera musculus). × 1⁄10. (From Flower's Osteology.)
The sternum in the Whale tribe is much more modified in the Whalebone Whales than in the Odontocetes. In the latter it is made up of several pieces, as in other mammals, which often, however, become coalesced. In the Mystacoceti this bone is a single piece, to which only one pair of ribs is attached, and its
