176 SYMPHALANGUS 
GENUS II. SYMPHALANGUS. THE SIAMANGS. 
‘i i -. a3 r = M. = 52. 
SYMPHALANGUS Gloger, Hand u. Hilfsb. Naturgesch., I, 1841, pp. 
XXVII, 34. Type Pithecus syndactylus Desmarest. 
Syndactylus Boitard, Jard. Plantes, Paris, 1842, p. 55. 
Siamanga Gray, List Spec. Mamm. Brit. Mus., 1843, pp. XVII, 1. 
Size large; skin of throat distensible overlying the large laryngeal 
sac, which is formed by the extension of the thyrohyoid membrane. 
Second and middle toes united by web as far as last joint. Skull large, 
supraorbital ridges more developed than in HyLopaTes; occipital 
region more truncate. Frontal lobes of brain flattened ; olfactory bulbs 
extend forward beyond frontal lobes of the cerebrum; occipital lobes 
small; cerebellum projects from below the cerebrum backwards. 
LITERATURE OF THE SPECIES AND SUBSPECIES. 
1820. Desmarest, Mammalogie. 
SYMPHALANGUS SYNDACTYLUS described as Pithecus syndac 
tylus. : : : 
1903. Miller, (G. S. Jr.), in Smithsonian Miscellaneous Collections. 
SYMPHALANGUS KLOssI first described. 
1908. Thomas, in Annals and Magazine of Natural History. 
Symphalangus syndactylus continentis first described. 
GEOGRAPHICAL DISTRIBUTION OF THE SPECIES AND SUBSPECIES. 
Sumatra contains S. syNDACTYLUs, and S. s. continentis is found 
in the Malay Peninsula possibly as far north as Tenasserim. South 
Pagi Island off the west coast of Sumatra has S. klossi. 
KEY TO THE SPECIES AND SUBSPECIES. 
A. With laryngeal sac. Color all black. 
a. ' Sine wery Taree a a a S. syndactylus. 
b.. Siee-sinaller Peery PV 8 oA S. s. continentis. 
. Size Very OMe iis a ee eek as ke we OO S. Rlossi. 
