1875.] Long-armed Apes. 3 



According to Dr. Theodore Cantor,* the H. variegatus, Kuhl (nee 

 Geoffroy, = H. agilis, Fr. Cuvier, = H. rafflesii, Geoffroy, = H. leucogenys, 

 Ogilby), is also an inhabitant of the Malayan peninsula, though less 

 numerous there than H. lar ; H. variegatus occurring elsewhere for certain 

 only in Sumatra, where it inhabits, together with H. syndactyly (Simia 

 syndaetyla, Raffles, Siamanga syndaetyla, Gray), the Siamang or Pouched 

 Gibbon. Heifer even states that the latter species has been found in the 

 southern parts of the Tenasserim provinces, as high as the 15th deg. 1ST. lat.f 

 Cantor, however, does not include it in his "List of Mammalia inhabiting 

 the Malayan Peninsula ; " \ but Mr. Wallace asserts that it " is not un- 

 common in some parts'' of that peninsula. § This, it may be suspected, 

 is a mistake, arising probably from the circumstance that — as Sir T. 

 Stamford Raffles remarks — " Samang or Siamang is the name given to 

 certain tribes of aboriginal inhabitants of the Malayan peninsula." || The 

 Siamang Ape, there is reason to believe, is quite peculiar to the island 

 of Sumatra, where only Mr. Wallace actually observed it; and the fact 

 that in other species of Gibbon the second and third digits of the foot are 

 occasionally connected, may have deceived Heifer and others into the sup- 

 position that such animals represented the veritable H. syndactylus. 



The Siamang is distinguished from all other Gibbons, not only by its 

 much greater size, but by its possessing an inflatable laryngeal sac. Mr. 

 Wallace remarks of it that " it moves much more slowly than the active 

 Hylobates" (-ZT. agilis, F. Cuvier), "keeping lower down on trees, and not 

 indulging in such tremendous leaps; but it is still," he adds, "very active, 

 and by means of its immense long arms, five feet across in an adult about 

 three feet high, can swing itself along at a great rate." In all of the 

 species of Gibbon the thumbs of both the hands and feet are separated 

 from the other digits to the base of the metacarpal and metatarsal bones ; 

 a character which is distinctly represented in no published figure that 

 I know of, nor am I aware that it occurs in any other quadrumana, 

 with the exceptions of the allied lemurian genera Indris and Propithecus. 

 It also is not generally understood that the long-armed Apes are true 

 bipeds when on the ground, applying the sole flatly, with the pollux 

 widely separated from the other digits ; the hands are held up to be out of 

 the way, rather than for balancing, and this even when ascending a flight 

 of steps, as I have seen repeatedly, but they are ever ready to seize hold 



* J. A. S. B. iv. p. 173. f Hid. vii. p. 868. % I.e. p. 173. 



§ " Travels in the Malay Archipelago," i. p. 134. || Tr. Lin. Soc, xiii. p. 242. 



