

100 



Hylobates syndactylus F. Cuvier 

 Sumatra: Paninggahan ; ad. cT (121) young cf (167). Skeleton cf (129.). 

 Sidjundjung; Skull (95). 



Muka-Muka near Manindjau; Skin (188). Skeleton (189). 



The specimen 121 has a sixth ulnar small flnger on the righthand 



at the basis of the fifth fingen It contains after tne 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 130 gr. 



The proportion of the weight of brain to weight of body is: 1,37 °/ . 

 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 °/ , agreeing with the youth of the specimen , that was about 

 two months old. '). 



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 

 Anthropornorpha has been the subject ofdifferent interesting researches 

 of late. I may quote here in the first place Denicker 2 ). 



My attention was first 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 paper ou the weight of brain of mammals (Bijdragen tot de Dier- 

 kunde. Amsterdam, LLolkoma, 1SSS) I have shown how the proportion of the woight of 

 brain to the weight of body is deponding from age. 



2) Denicker: Archives d. Zool. experimeut. 1885. 



