300 THE SKELETON OF THE RABBIT. 



The characters of a typical lumbar vertebra have 

 already been described : as a group they are charac- 

 terised by their large size, and the great development 

 of their processes, especially the transverse pro- 

 cesses. They increase in size from before back- 

 wards, the last but one being the largest. The first 

 two have hypapophyses : the last one has a short 

 stout centrum, and a stout crest-like neural spine. ' 



5. The sacral vertebrae. 



Strictly speaking, the sacral vertebrae are those 

 of which the expanded ribs directly support the 

 pelvis : and of these the rabbit has only one, or at 

 most two. A certain number of the succeeding ver- 

 tebrae, which are fused with each other and with the 

 last true sacral vertebra, are, however, commonly 

 included under the same name, the whole fused mass 

 being spoken of as the sacrum. Beckoned in this 

 way, the rabbit has three or more sacral vertebra?, 

 the lines of boundary between which can easily be 

 made out in spite of their fusion. 



a. The first sacral vertebra is much the largest, and is 



produced laterally into a pair of large wing-like 

 expansions which support the pelvis, and are 

 probably modified ribs fused with the vertebra. 

 The neural spine is large and nearly vertical. 



b. The hinder sacral vertebrae are much smaller, and 



decrease in size from before backwards. Their 

 number is variable, increasing with age through 

 fusion with the anterior caudal vertebrae. 



The anterior outer border of the second sacral 

 vertebra just touches the pelvis, but it is doubtful 

 whether any true costal element is present in it. 



6. The caudal vertebrae. 



These are about sixteen in number : they decrease 

 in size from before backwards, gradually losing all 

 their processes, and ultimately the neural arches as 



