84 ZOOLOGICAL GARDENS. 
sities of small size; and their cheek-pouches, in those 
species which appear to possess them, so inconsiderable 
as scarcely to deserve the name. The character, how- 
ever, which at once distinguishes them from the Cerco- 
pitheci, is found in their dentition, and more particularly 
in the form of the crown of the last molar tooth of the 
lower jaw, which, instead of four tubercles, one at each 
angle of the tooth as in the latter genus, offers five 
such projections on its surface, the additional one occu- 
pying the middle line of the tooth, and being placed 
posteriorly to the rest. ‘The Gibbons and the Macaques 
are also furnished with this additional tubercle. 
In the shape of their heads, and the expression of 
their physiognomy, the Semnopitheci bear so close a 
resemblance to the Gibbons, that it would be difficult 
to decide from an inspection of the head alone to which 
of the groups any particular species ought to be referred. 
In the earlier stages of their growth the forehead is 
broad and elevated, the cavity of the cranium propor- 
tionally large, and the muzzle but slightly prominent. 
But as they advance in age the forehead gradually 
diminishes in size, contracting in a remarkable degree 
the dimensions of the cavity within, and the muzzle is 
prolonged to a considerable extent. These changes, 
which are common to the whole tribe, but are pecu- 
larly striking in the present genus in consequence of 
the prominence of their foreheads in the young state, 
are accompanied by a corresponding change in the 
habits of the animals. When taken at an early age 
they are readily tamed, become playful and familiar, are 
extremely agile, although generally calm and circum- 
spect in their motions, and learn to perform a variety 
of tricks, which they execute with no little cunning and 
address. After a time, however, their playfulness wears 
off; their confidence is succeeded by mistrust; their 
