38 CERVICAL VERTEBRAL. [chap. 



Among the Afystacocdi,m the Right Whales (genus Bahcna) 

 the whole of the seven cervical vertebrae are usually united 

 into one mass b]^ their bodies, though sometimes the seventh 

 is free. The arches are also more or less united above, 

 though generally not in a continuous mass. Small slit-like 

 openings between the narrow pedicles of the arches permit 

 the exit of the cervical spinal nerves, and in the adult condi- 

 tion afford the only indication by which the number of the 

 united vertebrae can be ascertained. Already before birth 

 most of the bodies have coalesced, and it is even doubtful 

 whether they ever exist in a separate condition. 



The Fin Whales or Rorquals (genus Balcvnoptera) present 

 a totally different condition of cervical vertebrae, as these are, 

 as a rule, all distinct and free, though occasionally, as an 

 individual peculiarity, an irregular ankylosis may take place 

 between two or more of them. ^ 



l.'j(^ i5. — Anterior surface of atlas of common Fin Whale {Balaiioptera iintscnlii^), ■,''». 

 S)i foramen for first spinal nerve. 



In the common large Fin Whale of our coasts {B. 

 musculus) the atlas (Fig. i6) has short, stout, conical, imper- 

 forate transverse processes. The axis (Fig. 17) has a broad 

 oval body, high massive arch, very short odontoid process, 



^ See Professor Strutliers "On the Cervical Vertebras and their 

 Articulations in Fin Whales." {Jouniol of Anatomy and Physiology, 

 November 1872.) 



