100 
Hylobates syndactylus F. Cu vier. 
Sumatra: Paninggahan; ad. d 1 (121) young cf (167). Skeleton d 1 (129.). 
Sidjundjung; Skull (95). 
Muka-Muka near Manindjau; Skin (188). Skeleton (189). 
The specimen 121 has a sixth ulnar small finger on the right hand 
at the basis of the fifth finger. It contains after the investigation of 
Dr, Kohlbrügge, who is working out in my laboratory the anatomy 
of the genus Hylobates, two small phalanx-like bones but without muscles. 
In two specimens I stated the weight of the brain. This was as 
follows : 
N°. 121. 
length from vertex to anus . . . 62,5 cm. 
weight of body 9500 gr. 
weight of brain 180 gr. 
The proportion of the weight of brain to weight of body is : 1,87 %. 
N°. 167. 
length from vertex to anus . . . 28,5 cm. 
weight of body 1250 gr. 
weight of brain. . . 100 gr. 
The proportion of the weight of brain to weight of body is in this 
case 8 ü / 0 , agreeing with the youth of the specimen , that was about 
two months old. J ). 
It is an interesting fact, that the length of the fore limb of the 
Gibbons increases after birth proportionally much more than the hind 
limb. Therefore the enormous length of arms is more conspicuous in 
old specimens. 
The question about the proportion of fore and hind-limbs by the 
Anthropomorpha has been the subject of different interesting researches 
of late. I may quote here in the first place Denicker 2 ). 
My attention was ürst attracted to this point when I had the op- 
portunity of observing a living specimen of Hylobates lar. The length 
of the animal and of the limbs, measured at three different times were 
the following: 
1) In a previous papor on the weight of brain of mammals (Bijdrageu tot de Dier- 
kunde. Amsterdam, liolkema, 1888) I have shown how the proportion of the weight of 
brain to the weight of body is depending from age. 
2) Denicker: Archives d. Zool. experiment. 1885. 
