MK. W. H. FLOWER ON THE OSTEOLOGY OF THE SPERM-WHALE. 343 



The neural arch forms a distinct canal as far as the fifteenth caudal vertebra ; in the 

 sixteenth and following vertebrae the processes which represent it do not meet across 

 the middle line. In the Caithness Cachalot the canal terminates at the eleventh caudal, 

 in the Yorkshire specimen at the twelfth. In the anterior vertebrae (with elongated 

 bodies) the neural laminee arise from little more than the anterior half of the body, but 

 posteriorly, as the bodies decrease and the laminae actually increase in the antero- 

 posterior direction, they come to occupy nearly the whole length of the upper surface 

 of the centrum. This is best seen in the ninth and tenth. In the first caudal vertebra 

 the metapophyses form prominent flattened wing-like processes, projecting forwards 

 and outwards from the front border of the neural spine, having a deep groove between 

 them for the reception of the hinder edge of the spine of the last lumbar vertebra. 

 Their upper and anterior edges are thickened, rough, and slightly everted. They are 

 placed about halfway between the upper surface of the centrum and the highest part 

 of the spine. In the five following vertebrae their height from the centrum remains 

 almost precisely the same ; but the spine gradually diminishes, so that in the sixth 

 its upper edge comes to be on a level with these processes; at the same time they 

 alter in character, becoming shorter and thicker, and terminating in a nearly cir- 

 cular, flat, but very tuberculated or rugged surface, looking upwards and forwards ; 

 after the third they are so truncated and placed so near together upon the anterior 

 thickened edge of the neural spine, as to have scarcely any groove between them, 

 and to have quite lost the " clasping " character they exhibit in the lumbar region. 

 In the seA'enth caudal vertebra they have disappeared altogether, in consequence of 

 the diminution of the height of the spine, or are only slightly indicated in the laterally 

 thickened anterior extremity of the spinous process. Thereafter the spinous processes 

 are of a very simple nature, compressed from side to side, elongated from before back- 

 wards, and truncated above. The eleventh is less compressed ; the twelfth of quite 

 another form, broad and flat above, the sides meeting at a very open angle ; the thir- 

 teenth a mere irregular low tuberosity, perforated by a small canal ^s' liigh by j^" 

 wide. In the fourteenth and fifteenth the canal is much smaller in front than behind ; 

 in the last it is not so large as a goose-quill, and bridged over only for the space of 

 half an inch. In the remaining vertebrae the upper surface of the bone has four 

 tubercles, arranged in pairs — two near the front and two near the hinder edge, the 

 anterior pair being the largest. Traces of these can be discovered as far as the penul- 

 timate vertebra. 



In the anterior vertebrae of the series the transverse processes project outwards 

 with an inclination slightly downwards and forwards, from rather below the middle 

 of the side of the body. They soon diminish in length, and increase in width from 

 before backwards. In the ninth vertebra they are reduced to roughened longitudinal 

 rido'es ; in the tenth they have entirely disappeared, and their place is taken by a 

 slio-ht o-roove. In the Caithness Cachalot the transverse process is rudimentary in the 



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