ys: "The velocity of its movements
is wonderful; it escapes like a bird on the wing. Ascending rapidly
to the top of a tree, it then seizes a flexible branch, swings itself
two or three times to gain the necessary impetus, and then launches
itself forward, repeatedly clearing in succession, without effort
and without fatigue, spaces of forty feet."

Sir Stamford Raffles writes that it is believed in Sumatra that it
is so jealous that if in captivity preference be given to one over
another, the neglected one will die of grief; and he found that one
he had sickened under similar circumstances and did not recover till
his rival (a Siamang, _H. syndactylus_) was removed.

NO. 3. _HYLOBATES SYNDACTYLUS_.
_The Siamang_.

HABITAT.--Tenasserim Province, Sumatra, Malayan Peninsula.

DESCRIPTION.--A more robust and thick-set animal than the two last;
deep, woolly, black fur; no white supercilium nor white round the
face. The skull is distinguished from the skull of the other Gibbons,
according to Dr. Anderson, by the greater forward projection of the
supraorbital ridges, and by its much deeper face, and the occipital
region more abruptly truncated than in the other species. The index
and middle toes of the foot are united to the last phalange.

SIZE.--About three feet.

This Gibbon is included in the Indian group on the authority of Helfer,
who stated it to be found in the southern parts of the Tenasserim
province. Blyth mentions another distinguishing characteristic--it
is not only larger than the other Gibbons, but it possesses an
inflatable laryngeal sac. Its arms are immense--five feet across in
an adult of three feet high.

The other species of this genus inhabiting adjacent and other
countries are _H. Pileatus_ and _H. leucogenys_ in Siam; _H.
leuciscus_, Java; _H. Mulleri_ and _H. concolor_, Borneo.

_GENUS PRESBYTES--CUVIER'S GENUS SEMNOPITHECUS_.

These monkeys are characterised by their slender bodies and long
limbs and tails. Jerdon says the Germans call them Slim-apes. Other
striking peculiarities are the absence of cheek pouches, which, if
present, are but rudimentary. Then they differ from the true monkeys
(_Cercopithecus_) by the form of the last molar tooth in the lower
jaw, which has five tubercles instead of four; and, finally, they
are to be distinguished by the peculiar structure of the stomach,
which is singularly complicated, almost as much so as in the case
of Ruminants, which have four divi