1881 .] 
281 
[Lucas. 
lambdoiclal crest, and skulls so marked are invariably old. Even 
the old females — called S. satyrus — in which the temporal ridges 
do not unite, possess lambdoidal prominences as great as the 
skulls that are unmistakably females of S. Wurmbii. 
Now as the cheek protuberences are so characteristic of S. Wurm- 
bii, and as all specimens so-called have been shown to be old, we 
ought not to find them in young specimens. And this supposi- 
tion is borne out by facts, for the animals with cheek protuber- 
ences are invariably old males. Since the specific characters of 
S.Wurmbii are found only in very old animals, we are justified in 
assuming that that so-called species is merely the adult form of 
S. satyrus, and we have a final and convincing proof of this in 
the fact that, if we arrange a large number of skulls according to 
the amount of convergence of temporal ridges, we have a series 
in which the age increases as the distance between the ridges 
decreases. And since Simia morio and the species of Wallace 
are proved to have been based upon variations caused by age, the 
name Simia satyrus must stand for all Bornean Orangs and 
probably for those of Sumatra also, although it would be strange 
if some slight variation did not exist in specimens from the latter 
Island. 
Mr. Hornaday’s notes enable me to give definite figures as to 
the maximum size both of adult male and female Orangs. 
The males run from four feet up to four feet six inches, the 
average being a trifle over four feet two inches. Adult females 
vary from three feet seven and one-half inches to four feet, the 
average being three feet nine and one-quarter inches. 1 
In conclusion I subjoin a few notes showing the changes that 
take place in the skull of the Orang between youth and maturity. 
In the young the cranium is very round and smooth, the temporal 
ridges parallel, and slight, or even absent. The lambdoidal prom- 
inences are merely low elevations just above the meatus audito- 
rius, and the zygomata are slender. Incisors and canines are of 
moderate size. In the permanent dentition the upper median 
incisors are very wide — 11 to 14 mm. — and their roots, and 
1 All statements of the occurrence of Orangs six feet in height, or even five feet, are 
entirely without foundation; the largest specimen that I know of is four feet six and 
one-half inches. 
