376 NATURAL SCIENCE. December. 



gibbons have not been defined with any degree of exactitude. The 

 genus is restricted to Further India and the Malay Archipelago. 

 The N.W. corner of this region, Assam and the region to the 

 west of the Irawadi, reaching right up to the base of the Eastern 

 Himalayas, is occupied by H. hoolock — Anderson (291), Blyth 

 (295, 296), Blanford (294), and Theobald (3i4«). Next to it, 

 occupying the greater part of Burmah and stretching southwards in 

 the Malay Peninsula to an uncertain extent, is found H. lay — see the 

 authorities quoted above, Tickell (323) and Cantor (297). It is the 

 only species found in the Siamese province of Bangtaphan at the 

 base of the Malay Peninsula, where the writer has shot and dissected 

 six specimens. To the South of the Malay Peninsula, H. agilis is 

 said to occur (Cantor). H. leiicogenys occurs in Siam (Sclater, 319^) 

 probably in the Menam valley ; at any rate, the writer never saw it 

 in either the provinces to the S.E. or to the S.W. of that country. 

 In the S.W. provinces of Siam, and in Cambodia, occurs H. pileatus, 

 Gray (306), but how far northwards it extends is not known; Swinhoe 

 (320) reports the occurrence of a gibbon in China south of the 

 Yangstze. H. hainamts (Thomas, 322) occurs in the island of Hainan. 

 In Borneo two species occur, H. muelleri and H. leuciscus, Everett 

 (300), Miiller (272), Thomas (322^1); in Java, H. leuciscus, and in 

 Sumatra, H. agilis and H. syndactylus, which latter is also said to occur 

 on the Malay Peninsula, but this is very doubtful. Besides the authori- 

 ties quoted above, Geoffroy St. Hilaire (304), Rosenberg (267), 

 Trouessart (324), Hartmann (43), and Mohnike (260) may be profitably 

 consulted. 



Classification. — There are three questions pertaining to the 

 classification of gibbons that wait an answer. The first is : What 

 is their position among the primates ? The second : Should the 

 Siamang {H. syndactylus) be separated from the genus Hylohates ? 

 And the third : How many species are there ? 



As to the position of the gibbons in the series of primates, there 

 is a tendency at present, with which the writer is in sympathy, to 

 remove the gibbons altogether from the company of the anthropoids 

 and place them in a position intermediate between the great apes and 

 the cynomorphous monkeys — Kohlbriigge (313), Ruge (316), and 

 Vrolik (325). They are really cynomorphous monkeys adapted to 

 locomotion in an upright posture. In the prevailing systems of 

 classification, of which there are too many to make mention, the 

 gibbon is arranged with the great anthropoids in a family commonly 

 called Simiidai or Anthropomorpha — Huxley (49^5, 49^), Geoffroy St. 

 Hilaire (304), Duvernoy (22), Flower and Lydekker (301^), and 

 Broca {lo^a). 



As to the position of the Siamang, Gray seems to me to have 

 made a move in the right direction in placing it in a separate genus — 

 Sianmnga, including it with the common gibbon — Hylohates — in the 

 tribe Hylobatina. Its skull, teeth, and laryngeal sacs are strongly 



