lOG PROFESSOR OWEN ON THE OSTEOLOGY OF 



cles are still distinct. The lower half of the neural arch is more contracted than in the 

 last dorsalj and the lower zygapophyses are turned directly outwards. This outward 

 direction is much less in the Gorilla and Chimpanzee. 



The second lumbar vertebra {ib. fig. 2, 2) chiefly differs from the first by a slight 

 increase in the size of the centrum and in the length of the diapophysis. The upper 

 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 Gorilla, in the greater size of the neural arch, and in the greater 

 size of the zygapophyses as compared with the diapophyses ; from that of the Chim- 

 panzee it differs also in the greater relative size of the centrum. The anapophysial 

 tubercles are better developed in the Human vertebra, and are situated at the upper, 

 and not at the hinder part of the base of the diapophysis. The downward production of 

 the lower zygapophyses, occasioning the deep inferior emargination of the neural arch, 

 is also a characteristic distinction of the Human lumbar vertebrae. 



In the third lumbar vertebra (ib. fig. 2, 3, and fig. 5), both metapophysial (m) and 

 anapophysial tubercles continue distinct. The lower margin of the neural spine pro- 

 jects between two oblique ridges which diverge from the sides of that spine upon the 

 lower zygapophyses (2') : this character adds a marked distinction from the corre- 

 sponding bone in the Gorilla and Chimpanzee to the other differences pointed out in 

 the preceding lumbar vertebrae. 



The fourth lumbar vertebra (ib. fig. 2, 4) shows, like the corresponding vertebra in 

 the Gorilla and Chimpanzee, a decrease in the length of the diapophysis, but it likewise 

 shows a marked diminution in the vertical extent of the neural arch, occasioned prin- 

 cipally by a diminished length and increased breadth of the lower zygapophyses. The 

 anapophysial tubercles are distinctly developed. The body of the vertebra, though 

 much broader, is not longer than that of its homologue, the third lumbar, in the Chim- 

 panzee, and it is shorter than the corresponding vertebra in the Gorilla. 



The fifth lumbar vertebra (ib. fig. 2, s) is characterized not only by its superior size, 

 especially breadth, but by the great transverse expansion of tJie lower part of the neural 

 arch concomitant with the superior development and outward extension of the lower 

 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 downwards. The metapophysial tubercles are separated by a groove from 

 the anterior zygapophyses. 



Sacral Vertebra (PI. XXXVI.). — As we recede from the thoracic or central region of 

 the vertebral column, the deviations from the Human type become greater and the spe- 

 cific peculiarities of the Ape more marked. Even the differences of race begin to be 

 more clearly indicated in the structure of the vertebrre when we come to the sacrum, 

 which has induced me to contrast that bone in a European (fig. 7) with the sacrum of 

 an Australian (fig. 5) of the same age and sex. 



