ME. W. H. FLOWER ON THE OSTEOLOGY OF THE SPEEM-AVHALE. 341 



keel i-unning along the middle line below. They are also flattened between the neural 

 arch and the transverse processes, so that the general form of the end of the body of 

 one of these vertebrsc is pentagonal, or like a lozenge with the upper angle cut oflF. 

 The first of the series is rather different in form, having no distinct keel. In the older 

 individuals, as the Caithness specimen, the keels of the lumbar vertebrae are developed 

 to a still greater extent than in the Tasmanian skeleton. 



Fifth lumbar vertebra. 



1'he transverse processes are comparatively short (considerably less than the dia- 

 meter of the centrum) ; they have a very slight downward inclination, are of moderate 

 breadth, flat, and roundly truncated at their ends. They increase slightly in length to 

 the fifth, and then slightly diminish. 



The spinous, processes are high and broad, with a moderate slope backwards ; the 

 club-like lateral expansion noted in the upper end of the spinous process of the last 

 dorsal vertebra is seen also in the first lumbar, though in a less marked degree, and 

 gradually subsides in the following two or three. The height of the spine of the last 

 lumbar vertebra presents a considerable diminution. As in the Cetacea generally, the 

 metapophyses are strong, well-marked processes, projecting upwards and forwards from 

 the neural arch, embracing the hinder margin of the spine of the antecedent vertebra. 

 They do not form such broad expanded plates as in the true Whales ; but, on the other 

 hand, they are more distinct than in many other Delphinoids. One great peculiarity 

 which distinguishes them from most others, even including Hyperoodon, is their 

 gradual elevation upon the neurapophyses in passing from before backwards. In tlie 

 first lumbar vertebra they arise from the laminte of the neural arch by the sides of the 

 canal, and theu- upper edge is 6|" above the top of the body ; in the last they spring 



VOL. VI. PART VI. 3 B 



