704 PRIMATES 
reduced to five in the Mandrill (Cynocephalus maimon). In Macacus 
and Uacaria the shortness of the tail is attained by the small 
size of the vertebre themselves, the number of which may be 
from fifteen to seventeen. Other forms usually have from twenty 
to thirty-three caudals, the latter number occurring in Afeles 
(Fig. 335), where the tail is relatively the longest. The tail is, 
however, absolutely longest in Semnopithecus, Colobus, and their 
allies, the length being partly due to the size of the component 
vertebra. Chevron bones are present in all forms having a distinct 
tail; and, together with other processes for muscular attachment, 
attain their greatest development in Afeles. 
The vertebral processes known as metapophyses and anapophyses, 
which are generally inconspicuous in Man, and are but small in the 
Simiide, attain a large development in the lower forms. The 
metapophyses generally commence in the eighth or ninth dorsal, 
and continue to the anterior caudals, where they gradually merge 
in the prezygapophyses. The anapophyses, which are most de- 
veloped in the Cebidw, project outwards and backwards from one 
vertebra to embrace the prezygapophyses of the succeeding one. 
They occur generally in the same region as the metapophyses, but 
usually cease at the penultimate lumbar, although in some cases 
they can be traced on to the posterior cervicals and anterior 
caudals, in the latter region passing into the transverse processes. 
In most Apes the sternum is narrow, and consists of a more or 
less enlarged manubrium, followed by a chain of subequal and 
antero-posteriorly elongated bones, from three to six in number. In 
the Simzide alone is there a broad sternum, or one consisting of a 
manubrium, followed by a single bone only, as in Hylobates. The 
Orang presents a peculiarity, in that the sternum long remains 
made up of ossifications arranged in pairs, side by side, successively. 
The true ribs are seven in number on each side in the highest 
forms, but in Hylobates there are sometimes eight. In Ateles there 
are sometimes nine pairs. In Hapale the number varies from six 
to eight, and it is seven or eight in the other genera. The angles 
of the ribs are never so marked as in Man; although most marked 
in Hylobates.  Pithecia is distinguished by the greater relative 
breadth of the ribs. In no Ape is the thorax half as broad again 
as it is deep from back to breast ; but in the Simiidw its transverse 
diameter exceeds its depth by from about one-fourth to a little 
under one-third of the latter. In Ateles, and sometimes in Mycetes, 
the thorax is wider than deep, but in all the rest it is deeper than 
wide. 
In regard to the appendicular skeleton it may be observed that 
the Gorilla and Orang make the nearest approach to Man in the 
form of the scapula; and that the supraspinous fossa of this bone is 
largest in Gorilla and Afycetes, being remarkably small in Simia. 
