1865.] AXIAL SKELETON IN THE PRIMATES. 563 
The caudal vertebree generally increase in length as we proceed 
backwards from the sacrum, till about the 7th, 8th, or 9th, which, 
with the 10th and 11th, are the longest caudal vertebree in most lone. 
tailed forms. In Ateles, however, it is the 11th, 12th, 13th, and 
14th vertebrze which are the longest. But while in the long-tailed 
Simitde* the increase begins to be decidedly marked at the third 
In Man, the Simiine, the Nycticebine, Inuus (fig. 10), and In- 
dris the caudal vertebrae decrease in length as we proceed backwards, 
constituting a more or less prolonged coccyx. 
In Man and the Simiine the neural lamin never or very rarely 
form a closed canal, nor do those of all the first four caudal vertebree 
do so in Inuus and Indris ; but in the other groups the first four 
caudal vertebree always possess a complete neural arch. Sometimes 
in Semnopithecus, Cebus, &e., six are so formed ; but in Afeles alone 
are there as many as eight caudal vertebrze, each provided with such 
a structure. 
Neural spines are often developed on the first two or three caudal 
vertebrz in the long-tailed Simiide, on the first five in Lagothriz, 
and even on six in Afeles, but only on the first three or four of the 
other Cebide, and apparently on not more than three in the other 
genera of the order. ‘ 
In all the long-tailed Simiide and Cebide, except Inuus, the first 
four caudals are united together by distinctly articulating zygapo- 
physes. Sometimes in Inuus the second caudal vertebra has its 
Semnopithecine and Cynopithecine this failure first occurs in the 
fourth or fifth vertebra; in the Cebide generally, and in Hapale, 
not till the fifth or sixth ; In Lemur and Tarsius at about the fifth ; 
in Mycetes and Lagothrie at the sixth or seventh ; but in Ateles 
alone not till the eighth. 
In Man and the Simiine these processes are absent or quite rudi- 
mentary ; the same is the case as regards the metapophyses, which 
are scarcely more distinct in Inuus, the short-tailed Cynocephali, and 
Indris. Tn all the long-tailed forms they are more or less prominent, 
retaining their distinctness from the anterior zygapophyses longest 
in Ateles—namely, till the ninth caudal vertebra. 
The transverse processes of the caudal vertebre are peculiar and 
interesting. At first they are undivided, and project more or less 
