228 



PEOPESSOE FLOWEE ON THE EECENT ZIPHIOID WHALES. 



the transverse processes they are compressed or pinched in, as it were, at the middle of 

 each side ; and the inferior surface has a well-marked median keel. 



The arches arise nearer the anterior than the posterior end of the bodies. The spines 

 are long, compressed, of nearly equal antero-posterior breadth from base to apex, the 

 edges being approximately parallel, and roundly truncated above ; they slope backwards 

 formuig an angle of 45° with the long axis of the body. The anterior end of the arch, 

 below the spine, develops a conspicuous, broad, flattened metapophysis, the lower edge of 

 which carries another tubercle. The metapophyses remain at the same level throughout 

 the series, instead of gradually rising on the sides of the arch in the posterior lumbar 

 and caudal vertebrae, as in Physeter and Orca. 



The caudal vertebrw, reckoning from the first which bears a chevron bone at its 

 hinder border, are nineteen in number. 



The first resembles those of the lumbar region ; but it is distinguished from them by 

 wanting the median keel on the inferior surface, and by the pair of articular facets on 

 its hinder edge for the first chevron bone. Its spine is also shorter and considerably 

 broader than in the last lumbar vertebra. 



The bodies gradually shorten, though retaining their vertical height as far as the 

 ninth ; the tenth is much compressed ; the eleventh is small, being the " transitional 

 vertebra." The series of depressed vertebrse, or those of the tail proper, begins at the 

 twelfth ; but they are less flattened and less transversely extended than in the true 

 Dolphins. 



The under surfaces of the bodies are deeply channelled in the middle line, and have 

 strongly marked tuberosities at each corner for the attachment of the chevron bones ; 

 the anterior and posterior tuberosities of each side become united in the seventh and 

 succeeding vertebrae, enclosing a foramen which gradually diminishes in size. 



The spines gradually decrease to the tenth, after which they are no longer developed. 

 The transverse processes also gradually diminish, and cease to be apparent after the 

 eighth. The last vertebra is a small depressed triangular nodule. 



Antero-posterior length of the Bodies of the Thoracic, Lumbar, 

 and Caudal Vertebrce. 



