MR. W. H. FLOWER ON THE OSTEOLOGY OF THE SPERM-WHALE. 541 
keel running 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 vertebre is pentagonal, or like a lozenge with the upper angle cut off. 
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 vertebre are developed 
to a still greater extent than in the Tasmanian skeleton. 
Fig. 9. 
ruiootecE OE 
Fifth lumbar vertebra. 
The 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 the 
first lumbar vertebra they arise from the lamine of the neural arch by the sides of the 
canal, and their upper edge is 63” above the top of the body; in the last they spring 
VOL. VI.—PART VI. 3B 
