PLATE XX 



Plate XX is from the upper surface of a section through 

 the middle of the body of the fourth lumbar vertebra. The 

 plane of the section is 2.8 cm. anteriorly and 3.1 cm. poster- 

 iorly below that of the last section and is horizon- 

 tal. It passes just above the highest point of the crest of 

 the ilium. , , • 



