352 



BREAST BONE 



CHAP. 



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 



FIG. 186. Section through middle 

 line of united cervical vertebrae 

 of Greenland Eight Whale (Bal- 

 aena mysticetus). x J. a, Arti- 

 cular 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 verte- 

 brae ; 7, arch of seventh vertebra. 

 (From Flower's Osteology.) 



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 V-shaped chevron bones 

 below. 



FIG. 187. A, Sternum of Greenland Right Whale (Balaena mysticetus). x 

 Sternum of Common Rorqual or Fin Whale (Balaenoptera musculus). 

 (From Flower's Osteology.) 



B, 



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 



