1900.] ON THE BRAIN OF THE SIAMANG. 187 



Plate XVI. 

 Xenelaphis ellipsifer, p. 184. # nat. size. 

 Upper and side views of head and neck and of middle of body. 



Plate XVII. 



Fig. 1. AuMycephalus ntwhalis, p. 185. Upper and side views of head 

 and neck. 

 1 a. Lower view of head, X 1£. 

 1 b. Dorsal scales, X I5. 



2. Bkacophorus shelfordi, p. 185. 



3. Ixahis petersi, p. 185. 



4. Calophrynus heterochirus, p. 186. 



2. On the Brain of a Siamang {Hylobates syndactylus). By 

 Frank E. Beddard, M.A., F.R.S., Prosector and Vice- 

 Secretary to the Society. 



[Eeceived January 30, 1900.] 



The death of the Society's specimen of this rare Anthropoid 

 Ape 1 has enabled me to study an exceedingly well-prepared brain. 



In bringing before the Society some notes upon the cerebral 

 characters of this Ape, I am not breaking new ground. More than 

 thirty years ago Sir William Flower " described the general outline 

 of the brain of this Ape from a cast of the cranial cavity. The 

 account was accompanied by several woodcuts in the text, illus- 

 trating one remarkable feature in the brain, which was described in 

 the following words : " The most striking peculiarity of the brain 

 is the backward projection of the cerebellum beyond the level of 

 the cerebral hemispheres, a circumstance, as far as I am aware, 

 unknown in any of the Apes either of the Old or New World." 



This feature is not shown distinctly, but there are indications of 

 it, in Prof. Kohlbriigge's figure 3 of the brain of the Siamang. It 

 appears from the latter drawing that the cerebellum would be 

 visible on an inspection of the brain from above, though Kohlbriigge 

 remarks that the contrary is the case — without, however, referring 

 to Flower's observations on the matter, having been unable to study 

 his paper. Prof. Kohlbriigge examined eight brains of this Ape. 

 Other writers upon the brain-structure of Hylobates syndactylus 

 are Sandifort 4 and Waldeyer 5 . Thus not more than ten brains 

 of this species (or genus ?) have been studied. It is not therefore 

 perhaps superfluous to extend this list to eleven brains. 



1 Presented by Mr. Stanley S. Flower, F.Z.S. (See P. Z. S. 1898, p. 588.) 



2 Nat. Hist. Review, 1863, p. 279. 



3 " Versuch einer Anatornie des Genus Hylobates," in Max Weber's Z00L 

 Ergebn. Bd. ii. p. 186. 



4 Verhandelingen over de natuurlijke geschiedenis der Nederlandsche 

 overzeesche bezittingen. Leiden, 1840. 



5 " Das Gibbongehirn," Internat. Beitr. z. wiss. Med. Festschr. Virchow, 

 Bd. i. For this reference I am indebted to Dr. Keith's paper on the Gibbon in 

 ' Nat. Science,' vol. is. 



