10 Descriptions of Preparations. 



3. Cervical, Dorsal, and Lumbar Vertebrae of 

 Rabbit {Lepus Cuniculus). 



Great mobility is secured by the particular arrang-ements 

 observable in the region where the two upper cervical vertebrae 

 articulate with each other and with the skull^ and in the region of 

 the lower dorsal and upper lumbar vertebrae. On the other hand, 

 the transverse processes of the lower cervical vertebrae and the 

 imbricated neural spines of the upper dorsal vertebrae prevent the 

 possibility of any great range of movement between any two of 

 the constituent segments of those portions of the spinal column. 



The cervical vertebrae are seven in number, as almost invariably 

 in the Mammalian class; the numbers of the dorsal and lumbar 

 series are variable, but twelve and seven, the numbers of the dorsal 

 and lumbar vertebrae i*espectively in the Rabbit, are very common 

 numbers for those series throughout the class. The number of the 

 caudal vertebrae is the most variable, that of the lumbar next, that 

 of the dorsal less than that of the lumbar, that of the cervical the 

 least variable of these four sets of vertebrae. As the number of 

 the cervical vertebrae is all but invariable, the variability of the 

 length of the cervical reg'ion depends upon variations in the length 

 of the bodies of the seven vertebrae. The first cervical vertebra 

 or ' atlas^ is the widest from side to side of all the neck vertebrae ; 

 it has a low but broad neural arch, and superadded to it in front 

 a smaller arch which is in the perfect condition of the parts made 

 into a ring for the reception of the ' odontoid process^ of the next 

 vertebra by a transverse ligament. Its neural arch is overhung 

 by the spine of that vertebra, and it does not give any point of 

 attachment to the Ugamentuni nucliae. It contains two more or less 

 separated canals for segments of the vertebral artery ; one of them 

 pierces the base of its broad ^transverse process' from behind 

 forwards, the other turns more or less horizontally from without, 

 inwards, behind and below the articular processes. This latter 

 canal may be represented merely by a groove in the Rat, and 

 ordinarily has this imperfect character in the human subject. The 

 former has generally a short horizontal canal leading forward from 

 it and opening on the anterior surface of the transverse process ; it is 



