On a new Monkey and a new Squirrel. 181 
two forms are different, and that the 1899 specimen belongs 
to L. bow. 
The exact locality of the type of L. moreni is unfortu- 
nately unknown, as “ Chubut” is a province of considerable 
size, and there is no evidence as to where in it the specimen 
was obtained. 
XIX.—A new Monkey and a new Squirrel from the Middle 
Mekong, on the Hastern Frontier of Siam. By OLDFIELD 
THOMAS. 
(Published by permission of the Trustees of the British Museum.) 
SPECIMENS of the two following very distinct mammals have 
been obtained during a privately organized expedition to the 
Laos country on the Franco-Siamese boundary, and I am 
now privileged to describe them. 
Pithecus laotum, sp. n. 
A black species with white face. 
Fur soft and fine, that on shoulders elongated to form a 
mantle, its hairs some 100-110 mm. in length. Hairs of 
forehead all running backwards, without whorls, but those in 
front of and above the ears run inwards towards the centre 
of the occiput just behind the vertical crest ; behind these, 
‘again, the hairs run evenly backwards down the nape and 
back. On the occiput a prominent high projecting black 
crest apparently very like that of P. francoisz, with hairs 
40-50 mm. in length, points upwards and forwards at right 
angles to the smooth-lying frontal hairs among which it 
stands. 
Colour of the whole animal, with the exception of the 
head-marks, deep glossy black, the back, whole of under 
surface, limbs, and tail all uniformly black. Head with a 
narrow superciliary line and a few scattered hairs on the 
cheeks black. ‘Then the whole of the forehead and top of 
the head to halfway down the neck white, divided abruptly 
in the centre by the deep black of the occipital crest and a 
line succeeding it down the nape to the back. Area round 
and including ears, cheeks, and a line round below the chin 
also white. 
Skull apparently of normal build, the nasals short, neither 
specially flattened or convex ; nasal opening about half as 
broad as high. Canines very large and heavy. 
