811 



diverge from the sides of that spine upon the posterior zygapophyses : this character adds a 

 marked distinction from the corresponding bone in the Chimpanzee to the other differences 

 pointed out in the preceding lumbar vertebrae. 



5208. The fourth lumbar vertebra. 



This shows, like the corresponding vertebra in the Chimpanzee, a decrease in the length of 

 the diapophysis, but it likewise shows a marked diminution in the antero-posterior extent of 

 the neural arch, occasioned principally by a diminished length and increased breadth of the 

 posterior zygapophysis. The anapophysial tubercles are distinctly developed. The body of 

 the vertebra, though much broader, is not longer than that of its homologue, the third lum- 

 bar, in the Chimpanzee. 



5209. The fifth lumbar vertebra. 



This is characterized not only by its superior size, but by the great transverse expansion of 

 the hinder part of the neural arch concomitant upon the superior development and outward 

 expansion of the posterior zygapophyses. The diapophyses and neural spine are shortened : 

 the anapophyses appear like a part of the upper border of the base of the diapophysis pinched 

 up and produced backwards. The metapophysial tubercles are separated by a groove from 

 the anterior zygapophyses. 



5210. The sacrum. 



This consists of five anchylosed vertebrae. They differ from the sacral vertebras of the 

 Chimpanzee by their greater breadth and by their anterior concavity both lengthwise and 

 transversely. The nervous foramina are relatively much larger : the spinous processes are 

 shorter and thicker. The two anterior sacrals and a small part of the third form the sacro- 

 iliac joint. The neural arch of the last two sacral vertebrae is incomplete. 



5211. The first coccygeal vertebra. 



It is less flattened and is shorter than in the Chimpanzee : the neurapophyses are longer, 

 the diapophyses are shorter. 



5212. The first pair of ribs and manubrium sterni. 



The neck of the rib is longer in proportion to the body, and this is relatively broader and 

 flatter than in the Chimpanzee. The whole rib describes a greater portion of a circle. The 

 manubrium is longer in proportion to its breadth, and the two clavicular tuberosities are 

 more developed. 



5 L2 



