100 PROFESSOR OWEN ON THE OSTEOLOGY OF 



number — the thirteenth, however, answering to the first lumbar in Man, with the pleur- 

 apophyses retained as free elements — -differ in the greater length of the spines of the first 

 live vertebrse, which progressively decrease to the length they present in the Human 

 subject, but with greater thickness, and in the last three with greater vertical extent. 

 The bodies of the middle dorsal vertebree are shorter in proportion to their breadth ; the 

 diapophyses are thicker, stand more directly outwards (fig. 3, d), and the costal surfaces 

 are more concave and oblong; the metapophysis which projects distinctly in the eleventh 

 vertebra in Man (PI. XXXIV. fig. 2, u, m), does not so project until the twelfth in the 

 Gorilla {ib. fig. 1, 12, m). 



In the first dorsal vertebra the centrum is larger from before backwards, and the spine 

 is twice the length of that in Man and is less inclined downwards. The zygapophyses are 

 larger than in Man ; the costal surface is more produced on the side of the body : but the 

 chief difference is in the position and direction of the diapophysis, which in the Gorilla 

 projects directly outwards below the level of the upper zygapophysis ; the fore part of 

 the base of the neurapophysis is less deeply grooved in the Gorilla. 



The same general differences may be noticed in the four succeeding dorsal vertebrae ; 

 the spine, however, becomes shorter and the centrum larger than in the first vertebra; 

 the neural arch rises more abruptly beyond the upper zygapophysis. In the sixth dorsal 

 vertebra the neural spine is reduced to the same length as is the corresponding spine in 

 Man ; the centrum is larger, the neural canal of the same size, the posterior costal pits 

 are longer, the diapophyses still stand out more transversely. The neural spine is less 

 obliquely bent backwards, and is thicker vertically, though not longer; the upper zyg- 

 apophyses are more produced ; the diapophyses are broader and somewhat shorter. 



The tenth dorsal vertebra of the Gorilla (PI. XXXIV. figs. 3, 5, & 7) is contrasted in 

 corresponding views with that of Man {ib. figs. 4, 6, & 8). The under surface of the 

 body (c) is somewhat smaller in the Gorilla, and the surfaces (pi) for the ribs are better 

 marked : a slight difference in the aspect of the zygapophyses allows more of their arti- 

 cular surface to be seen in fig. 3, at z' ; the greater difference in the direction of the 

 diapophyses (d) is also well shown. The somewhat thicker diapophyses (d) and summit 

 of the spine (ns) are shown in fig. 5, as compared with fig. 6 ; and the more prominent 

 upper zygapophyses (0, z) in Man are exemplified in both figs. 6 & 8. 



In the eleventh dorsal vertebra the neural spine is more expanded at its extremity 

 than in Man. 



In the twelfth there are distinct and well-developed metapophyses (fig. 1, 12, m) pro- 

 jecting from the upper part of the diapophyses behind the upper zygapophyses. This 

 vertebra corresponds in this character with the eleventh of the Human subject. The 

 neural spine is broader vertically and thicker, especially superiorly. There is but one 

 costal surface on each side of the base of the neurapophysis. The diapophyses (rf) are 

 reduced in size, the metapophyses equalling them. 



In the last dorsal vertebra of the Gorilla (fig. 1, 13), which answers to the first lumbar 



