420 



seen in Figure 4. Each tuberosity then is formed by the fusion of 

 four epiphyses viz, two "transverse" — epiphyses those of the fourth 

 and fifth — and two "costal" — those of the third and fourth — , and 



the comma-shaped masses may often 



be seen in the adult form as in 



Fig. 6. 



Epiphyses of the mam- 



millary processes: 



In the first sacral vertebra 



each mam miliary process is formed 



by epiphysis which is well developed 



at the 18th year. 



Fig. 6. An adult sacrum from the 

 right side and behind. Notice the transverse 

 processes T, and the permanent comma-shape 

 of the lower ones. 



Epiphyses of the spinous processes: 



In those vertebrae in which spinous processes are developed, there 

 seems to be little doubt that epiphyses^ are developed, and they cer- 

 tainly exist in those specimens in my possession. 



The manner of fusion or partial fusion of the fifth 

 lumbar vertebra with the sacrum: 



This is will seen in Figure 2. 



The costal process of the fifth lumbar vertebra becomes enormously 

 enlarged, and is capped by an epiphysis. This epiphysis fuses with 

 the epiphysis of the transverse process of the first sacral vertebra, the 

 two forming a common wedge-shaped mass which then descends for 

 some distance along the auricular facet (T. 1 Fig. 2). 



The whole process may be summed up in the following way. 



Each auricular facet is formed in the main by the development 

 and fusion of four costal epiphyses two of which belong to S. 1, and 

 two to S. 2. 



Each tuberosity is formed by the fusion of the costal epiphysis of 

 S. 3 and S. 4 with the epiphyses of the transverse processes of S. 4 

 and S. 5. 



Each sacral transverse process with the exception of the second 

 develops an epiphysis. 



The mammillary processes of the first sacral vertebra only are 

 formed by epiphyses. 



Finally the spines of the first three sacral vertebrae when com- 

 plete develope an epiphysis. 



