12 PROCEEDINGS OF THE NATIONAL MUSEUM VOL. 125 
is Aotus (the douroucouli), the only nocturnal higher primate and 
one of the most primitive monkeys in existence. 
OLD worRLD MoNKEYS.—The Old World monkeys comprise the 
single family Cercopithecidae; of the two subfamilies, the Colobinae 
and the Cercopithercinae, only the last named are presently of 
interest to the research scientist. The contribution of the Cercopithe- 
cinae to human research has been discussed by Jolly (1966). 
Macaca mulatta, the rhesus monkey, the ‘‘monkey” of medical 
literature, is too well known to merit discussion here; its use in the 
identification of the Rh blood factor and in the development of 
poliomyelitis vaccine is common knowledge. The breeding record of 
the rhesus macaque, its toughness, availability, and cheapness make 
it the best all-round research animal. Certain other macaque species 
as the crab-eater, the pig-tail, the stump-tail, the bonnet, and the 
Japanese macaque all breed well in captivity. The last mentioned 
promises to be especially valuable as a species that can be bred freely 
in open-air compounds, even in high latitudes. 
The closely related Celebes black ‘‘ape’” (Cynopithecus niger) is 
another primate that seems to breed well in captivity. As a bonus, 
Celebes apes are, for Old World primates, quite friendly animals. 
One might guess that imported stocks of Cynopithecus are never 
likely to be adequate for extensive research usage due to the restricted 
range of the species. Their future usefulness will have to depend 
largely on domestic breeding programs. 
Baboons have grown in popularity in recent years and are becoming 
biologically very well documented (Vagtborg, 1965). They are of 
particular value in surgical procedures (Moor-Jankowski, 1967). 
Baboons have been used extensively in studying the etiology of 
atherosclerosis and other cardiovascular diseases of man at Sukhumi 
in the U.S.S.R., for instance, and at the Southwest Foundation, San 
Antonio, Texas. 
The leaf-eating section of the Cercopithecidae, the Colobinae of 
southeast Asia (Presbytis, Nasalis, etc.) and Africa (Colobus) are so 
specialized in their diet and, relatively speaking, so little known 
biologically that they have no place in medical laboratories at the 
present time. A possible exception to this generalization is the Hanu- 
man or entellus langur (P. entellws), which is hardier than most other 
species and more ground adapted (Jay, 1965). 
The remaining Old World monkeys to which reference should be 
made have been grouped by some taxonomists (Jolly, 1965) into a 
tribe, the Cercopithecini, that includes the following genera and 
subgenera: Cercopithecus, Cercopithecus (Miopithecus), Cercopithecus 
(Allenopithecus), and Erythrocebus. This tribe is not generally regarded 
as important in biomedical research, but there are at least three 
