810 



5203. The eleventh dorsal vertebra. 



The metapophysial tubercle which was slightly indicated in the preceding vertebra becomes 

 more distinct. The centrum continues to increase in size. 



5204. The twelfth dorsal vertebra. 



The centrum continues to enlarge, and the neural spine to gain in antero-posterior extent. 

 The metapophyses are well developed : the anapophyses may be recognized distinctly : the 

 diapophyses are reduced to smooth tubercles without an articular facet. The neural arch of 

 this vertebra contracts in breadth posteriorly, concomitantly with the modified shape and 

 direction of the posterior zygapophyses, which are elongated and incline more obliquely out- 

 ward than in the preceding vertebra. This modification does not characterize the corre- 

 sponding vertebra in the Chimpanzee. The anterior emargination of the neural arch is wider 

 in the twelfth dorsal, which is distinguishable from the eleventh not only by this character, 

 but by the distinctness and greater length of the metapophyses, and by the greater length 

 and minor breadth of the part of the neural arch supporting the posterior zygapophyses. 



5205. The first lumbar vertebra. 



The centrum is much increased in size, and the neural spine in extent. The metapophy- 

 sial tubercles are also enlarged, but do not project so freely, by reason of the extension of 

 the articular surfaces of the anterior zygapophyses upon the inner sides of their base. The 

 diapophyses are much increased in length. The anapophysial tubercles are still distinct. 

 The hinder half of the neural arch is more contracted than in the last dorsal, and the poste- 

 rior zygapophyses are turned directly outwards. 



5206. The second lumbar vertebra. 



This chiefly differs from the first by a slight increase in the size of the centrum and in the 

 length of the diapophysis. The anterior zygapophyses are larger and look more directly 

 inwards. Both metapophysial and anapophysial tubercles are distinct. This vertebra differs 

 from its homologue, the first lumbar vertebra, of the Chimpanzee, in the greater size of the 

 body and neural arch, in the greater size of the zygapophyses as compared with the diapo- 

 physes, and more especially in the greater size of the neural spine. The anapophysial 

 tubercles are better developed in the Human vertebrae, and are situated at the upper, and not 

 at the hinder part of the base of the diapophysis. The backward production of the posterior 

 zygapophyses occasioning the deep posterior emargination of the neural arch is also a charac- 

 teristic distinction of the Human lumbar vertebrae. 



5207. The third lumbar vertebra. 



Both metapophysial and anapophysial tubercles continue distinct on this vertebra. The 

 posterior margin of the neural spine projects distinctly behind two oblique ridges which 



