556 ANATOMY OF VERTEBRATES. 



of the last cervical or first lumbar vertebrae happen to be elongated 

 and free, they are added to the numbers of ^ pairs of ribs ' in an- 

 thropotomical computation. 



As a rule, the coalesced pleurapophyses make long ^ transverse 

 processes ' in the lumbar vertebrae ; in the first of Avhich, as com- 

 pared with the last dorsal, the centrum is much increased in size, 

 and the neural spine in extent. The metapophysial tubercles are 

 also enlarged, but do not project so freely, by reason of the ex- 

 tension of the articular surfaces of the anterior zygapophyses 

 upon the inner sides of their base. Tlie anapophysial tubercles 

 are still distinct. The second lumbar vertebra chiefly differs 

 from the first by a slight increase in the size of the centrum 

 and in the length of the diapophysis. The anterior zygapo- 

 physes are larger and look more directly inwards. Both metapo- 

 physial and anapophysial tubercles are distinct. The backward 

 production of the posterior zygapophyses occasioning the deep 

 posterior emargination of the neural arch is a characteristic dis- 

 tinction of the Human lumbar vertebrae. Both metapophysial 

 and anapophysial tubercles continue distinct on the third lumbar 

 vertebra. The body of the fourth lumbar vertebra, though much 

 broader, is not longer than that of its homologue, the third lumbar, 

 in the Chimpanzee. It likcAvise 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 deve- 

 loped. The fifth lumbar vertebra 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 develop- 

 ment and outward expansion of the posterior zygapophyses. The 

 diapophyses and neural spine are shortened: the anapo2)hyses 

 appear like a part of the upper border of the base of the diapo- 

 physis pinched up and produced backwards. The metapophysial 

 tubercles are separated by a groove from the anterior zygapo- 

 physes. 



The sacrum, fig. 366, consists of five anchylosed vertebra?. 

 They differ from those of the Gorilla by their greater breadth 

 and by their anterior concavity both lengthwise and transversely. 

 The anterior nervous foramina, h, are relatively much larger : the 

 spinous processes are shorter and thicker. The coalesced pleura- 

 pophyses, p/, h, of the two anterior sacrals chiefly form the sacro- 

 iliac joint. The neural arch of the last two sacral vertebras, r/, 

 c, is incomplete. 



The first coccygeal vertebra, ib. c, e, is less flattened and is 



