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 
five vertebr, 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 vertebre are shorter in proportion to their breadth ; the 
diapophyses are thicker, stand more directly ontwards (fig. 3, d), and the costal surfaces 
are more concave and oblong; the metapophysis which projects distinctly in the eleventh 
vertebra in Man (Pl. XXXIV. fig. 2, 11, 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 vertebre ; 
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 (P]. XXXIV. figs. 3, 5, & 7) is contrasted in 
corresponding views with that of Man (2b. figs. 4, 6, & 8). The under surface of the 
body (c) is somewhat smaller in the Gorilla, and the surfaces (pl) 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 2’; 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 (z, 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 (d) 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 
