52 



Anatomy of the Rabbit. 



region is reduced to a vestigial coccyx, consisting of coalesced- 

 vertebrae. 



The individual vertebra is made up of a more massive ventral 

 body, upon which is set a bridge of bone forming the arch. Both 



• 



Fig. 25. Mid-lumbar vertebrae of bear (A. fifth), rabbit (B, fifth), and man (C 

 third): a, inferior articular process; c, body; m, mamillary and superior articular pro- 

 cess; s, spinous process; t. transverse process. 



body and arch bear processes which reach into the surrounding 

 muscles, and serve for their support. The principal processes are 



THE FORMS mid-dorsal or spinous, 



of vertebrae, lateral or transverse, 



and, in the lumbar re- 

 gion, dorsolateral or mamillary. Gener- 

 ally speaking every vertebra has three 

 principal functions — to support the body, 

 to protect the spinal cord, and to offer 

 support for muscles. 



Any vertebra of the rabbit may be com- 

 pared with the corresponding vertebra of 

 any mammal or in a general way with those 

 of any vertebrate. The fifth lumbar 

 vertebra of the rabbit, for example, would be found distinguished 

 by the great development of its processes, since the latter support 

 powerful muscles used in leaping. The corresponding human 

 vertebra, or the third as functionally more nearly equivalent, is 

 weak in muscular expansion, but its body is massive for purposes of 



Fig. 26. Lumbar vertebra of 

 four-day -old rabbit. Cartilage 

 dotted, bone shaded. X 5. 



