THE MANDIBULES OF PHAYREI''''S AND FRANCOIS'''' LEAF MONKEYS
菲氏叶猴与黑叶猴的下颌骨

Researching on 22 adult skulls (including 15 for phayrei' s leaf monkeys and 7 for francois' leaf monkeys), some aspects were shown on the mandibular dimensions btween two leaf monkeys. They are as follows: 1 Among 21 items of the mandibular dimensions, 4 of them reach the level of significant difference (P<0.05).They include:length of M1 and M2:breadlh of the M2 (Those of the phayrei's leaf monkeys are bigger than that of francois' leaf monkeys) and the length of canine (Those of the francois' leaf monkeys are bigger than that of phayrei's leaf monkeys). 8 of them reach the level of more significant difference (P<0.01). That is: length of I1 and I2; breadth of condyle (Those of phayrei's leaf monkeys are bigger than that of the francois' leaf monkeys); breadth of mandibulc and ramus; height of mandibule, corpus and ramus (Those of the francois' leaf monkeys are bigger than that of phyrei's leaf monekys). 2 The sequance of the mandibular molars size is M3>M2>M1 (exception of M2>M3 in the phayrei's leaf monkeys), which still remian the sequance of the Old world Monkeys'. 3 Considering the position of masscter on the mandibule, francois' leaf monkeys have more rnastcating efficiency than phayreis' leaf monkys have (because the dimensions of the ramus, condylar areas and mandibular breadth, length on the remains of the francois' leaf monkeys arc bigger than that of the phayrei's leaf monkeys). So we phypothesize that francois' leaf monkeys eat more fruits but phayrei's leaf monkeys cat more seeds and leaves.