The average body mass for an adult male douc langur is around 10.9 kilograms, and for the female it is around 8.2 kilograms. This species has a sacculated stomach to assist in the breakdown of cellulose. The douc langur has a dental formula of 2:1:2:3 on both the lower and upper jaws (Ankel-Simons, 2000). The molars and premolars have high cusps and the incisors are narrow. The hindlimbs are longer than the forelimbs on the douc langur. Both sexes of this species have vibrissae along the supraorbital torus (Lippold, 1977). The penis of the adult male is bright red when erect (Lippold, 1977). The infant douc langur has a pelage coloration where the face is black with two light stripes beneath the eyes, the top of the head is reddish-black, and the back is light chestnut in color with a black line along the back (Hick, 1972; Lippold, 1998). The arms and legs of the infant are chestnut-reddish-brown, and the color is brighter on the legs than on the arms (Hick, 1972; Lippold, 1998). The hands and the feet of the infant are black, and the tail is whitish with a gray tip (Hick, 1972). The neck and the tail root of the infant are chestnut and the ventral side is a pale chestnut color (Hick, 1972). White round spots near the rump patch develop on males at about 8 months, and this can be used to tell males from females (Lippold, 1998).