THE CHIMPANZEES AND ORANGS. 101 



in Man (PI. XXXV. fig. 2, i ), the chief difference is the articular surface (p) for the free 

 rib-element. The metapophysis is well developed in this vertebra. 



The increase in the size of the centrum, as the dorsal verteb^^e descend in the Gorilla, 

 is more in the antero-posterior than in ihe transverse diameter ; and in the size of the 

 spine it is more in the vertical diameter than in length. 



The dorsal vertebra of the Chimpanzee accord very closely, except in size, with those 

 of the Gorilla, and manifest the same general distinctions from those of Man. 



In the first dorsal the bases of the neurapophyses, instead of being produced upwards, 

 have those angles as it were truncated, to form the articulation with the heads of the 

 first pair of ribs. The breadth of the centrum is augmented, and also, in a more espe- 

 cial degree, that of the diapophysis, which is excavated below for articulation with the 

 tubercle of the rib. The neural spine is increased in vertical extent, and is as long as 

 that of the last cervical ; it is consequently longer than in Man. 



In the second dorsal the centrum is larger than in the first ; the upper zygapophyses 

 are more approximated and distinct from the diapophyses, which thereby appear to be 

 longer : the neural spine is somewhat longer than in the first dorsal. 



The third differs from the second dorsal in its narrower upper neural emargination, 

 iu the somewhat shorter diapophyses and longer neural spine. 



In the ninth dorsal the centrum presents a marked increase of size : the spine is 

 "thicker transversely and more expanded at its end. 



In the tenth dorsal there is an increase in the size of the body and of the neural 

 spine ; and the inferior costal surface is replaced by a non-articular tubercle : that sur- 

 face is retained and well marked in the correspondingvertebra of the Gorilla (PI. XXXIV. 



fig. 1, 10,/). 



In the twelfth dorsal the metapophysis projects distinctlyupwards from the diapophysis. 



In certain characters the thirteenth dorsal resembles the last or twelfth dorsal 

 of Man : for instance, in the distinct and well-developed metapophyses, which are thicker 

 and longer in the Chimpanzee ; also iu the narrower and longer lower part of the neural 

 arch, concomitant with the change of position of the lower zygapophyses. The di- 

 apophysis still shows, in the Chimpanzee, an articular surface for the tubercle of the 

 thirteenth rib. The neural spine is longer and larger than in Man, especially in its 



vertical extent. 



Although the Orang more resembles Man than does either the Gorilla or Chim- 

 panzee in the number of dorsal vertebrae, or those characterized by moveable ribs, yet 

 the individual vertebrae do not offer so close a similarity to the corresponding Human 

 ones as they do in the Chimpanzee. The spines of the first and second dorsals are equally 

 characterized by their superior length. The spine of the third dorsal has an upper and 

 lower prominence: the succeeding spines gradually diminish in length, but increase in 

 breadth and vertical extent to the penultimate lumbar. 



In the dorsal series of a halt-grown Orang {Pilhecus Wurmbii) I have noticed that the 



