1865. ] AXIAL SKELETON IN THE PRIMATES. 555 
or less oblique ; but there is great, apparently even individual, varia- 
tion in this respect. This character appears least marked in Man. 
In Lemur the under surfaces of the second, third, and fourth ver- 
tebrz have often a marked median ridge, such as is found in no An- 
thropoidea. This is wanting in the Slow Lemurs, but is greatly de- 
veloped in Indris, the posterior part of each centrum being produced 
so as to underlap the centrum next behind in a remarkable manner. 
The breadth of each centrum (taking the third cervical vertebra 
as the standard of comparison) rarely exceeds its antero-posterior 
dimension so much as it does in Man. Yet it does so in Nycticebus, 
where the breadth is twice and a half the length. 
In Troglodytes and Simia the length is already greater in propor- 
tion to the breadth than in Man; in Hylobates the two dimensions 
are nearly equal, as also in the other genera, if the length does not 
slightly exceed the breadth as it does in Cynocephalus, Ateles, and 
Mycetes. In Lemur and Indris the length exceeds once and a half 
the breadth. 
DorsaL VERTEBRE. 
The number of dorsal or rib-bearing vertebree varies from a mini- 
mum of 1] to a maximum of 16. 
In Man and the Simiade there are generally 12 or 13, and rarely 
14 or only 11 dorsal vertebre. 
In Man the number is normally 12, very rarely 13. 
In the Gorilla it is, apparently, always 13. 
In the Chimpanzee there are normally 13 dorsal vertebrz ; but 
occasionally there are 14*, or only 12+. 
In the Orang there are 12. 
In Hylobates 12, 13, or rarely 14f. 
In Semnopithecus and Colobus 12. 
In Cercopithecus 11, 12, or 13. 
In Macacus 11 or 12, very rarely 13§. 
In Cynocephalus 12 or 13. 
In the Cebide@ the range is different, namely from 12 || to15, thus :— 
In Ateles 13 or 14. : 
In Lagothrix 14, 
In Cebus 13, 14, or rarely 12. 
In Mycetes 13 or 14. 
In Pithecia, Brachyurus, and Chrysothrix 13. 
In Nyctipithecus from 13 to 15. 
* Cur. Lecgons d’Anat. Comp. vol. i. p. 177. 
t In a skeleton recently added to the Hunterian Collection (and to which Mr. 
W.H. Flower kindly directed my attention) there are but twelve dorsal vertebra, 
and only the usual number of lumbar vertebre, that answering to the fifth lum- 
bar of Man forming part of its sacrum. 
¢ No. 5029 in the Museum of the Royal College of Surgeons (Osteological 
Catalogue, vol. ii. p. 756). 
§ Nos. 4860 and 4942 in the Collection of the Royal College of Surgeons 
(Osteological Catalogue, vol. ii. pp. 744 & 749). 
|| In one instance I have found only eleven—namely, in Callithrix personatus 
(no. 51d in the Osteological Collection of the British Museum). 
