OSSEOUS SYSTEM OF MAMMALIA. 



57 



Besides the cervical, dorsal, lumbar, and sacral vertebrae, there are 

 those supplemental rudimentary vertebrae, termed coccygal or caudal, which 

 constitute the tail : these usually have no distinct body and processes, nor 

 any aperture for the transmission of the spinal chord ; but are simply 

 elongated bones, placed end to end. 



In general, though not always, the cervical vertebrae are shorter and 

 smaller than the dorsal or the lumbar ; but their breadth is considerable, 

 owing to the amplitude of the transverse processes, which are bifurcated, 

 and which (if not in all, at least in the greater number of the vertebrae,) 

 are perforated at their base, for the transmission of the cervical vein and 

 artery. In Man, and many other animals, as the Kangaroos, various 

 Pachydermata and Rodentia, the foramen, thus formed, exists in all the 

 seven cervical vertebrae: in others, on the contrary, as the Elephant, 

 the Rhinoceros, the Hog, the Horse, most ruminants, and the Quad- 

 rumana, it does not exist in the seventh vertebra. In the Tamanoir, 

 according to Meckel, it is absent in the second, third, fourth, and seventh 

 vertebrae, while it is distinct in the others. In the Giraffe, the perforations 

 for the arteries are large ; they are present in the seventh, as well as in the 

 rest of the cervical vertebrae ; but they are situated above the transverse 

 processes in the side of the bodies of the vertebrae : and Professor Owen 

 observes, that, although this position of the arterial foramina is somewhat 

 peculiar, yet that, in this respect, the Giraffe comes nearer to the horned 

 ruminants than to the long-necked Camelidae. The following figures (39, 

 40, 41, 42, 43), represent one of the cervical vertebrae of Man, in different 

 aspects. 



40 



Figs, 39 to 43. A cervical vertebra in different aspects. 



Fig. 39, Superior view. 40, Inferior. 41, Anterior. 42, Lateral. 43, Posterior. a, the body of the vertebra ; b, the 

 spinous process, bifurcate at its extremity ; c, c, the oblique processes ; rf, d, the forked, or branched, transverse processes i 

 , e, the cervical foramina; /, the spinal canal. IThe same letters "refer to the same part in all the above figures.) 



In all Mammalia, from Man downward, the number of cervical ver- 

 tebrae is seven, this rule, however, is not without an exception. Some 



