INTRODUCTION xvii 



5 lumbar, while Lagothrix and Ateleus have but 4 ; Cebus has 

 5 and 6 lumbar, while Aoxus has 8, and 24 caudal ; Pithecia 6 lumbar ; 

 Callicebus and Saimiri 7 lumbar, the last genus with 28 to 30 caudal ; 

 Callithrix has 6 and 7 lumbar, and 27 to 33 caudal ; Nycticeeus 6 

 and 8 lumbar, and 8 and 11 caudal, and Perodicticus 7 lumbar and 

 20 caudal vertebrae. 



The Apes and Monkeys of the eastern hemisphere have thirty-two 

 teeth, the same as in Man, but the Primates of the western hemisphere, 

 excepting those of the Family Callitrichid^ which also have thirty- 

 two, have thirty-six, the excess being two pairs of premolars, one pair 

 each in the upper and lower jaws. The canines in the males of all 

 Primates are large and extend beyond the tooth rows, and are separated 

 from the incisors by a diastema. 



The ANTHROPOIDEA have been divided by Authors into five 

 Families, Callitrichid^, (usually designated as Hapalidce), Cebid-e, 

 Ccrcopithecida, (Lasiopygid^), Simiidw (Pgngiid.e of this work) 

 and Homonida. To these in the present work has been added Hylo- 

 BATiD^ comprising the Gibbons, which on account of their structure 

 and mode of life seem more properly separated from, than united with, 

 the great Apes. The Gibbons are the only Apes that habitually walk 

 in an upright posture. 



The Monkeys of the New World, excepting those of the genus 

 Cacajag, differ from all others, besides the number of the teeth in 

 having more or less prehensile tails, this member being frequently bare 

 beneath for a greater or less space at the tip, forming a grasping 

 surface and preventing slipping ; and the members of the genus 

 Ateleus are so expert with this organ as to make it serve the purpose 

 of a fifth hand, not only for holding on to the limbs of trees, even 

 suspending the animal without any other support, but often for con- 

 veying food to the mouth. Members of other genera, as Brachy- 

 TELEUS, Alouatta, Lagothrix, Cebus, ctc, are provided with pre- 

 hensile tails but not all have a bare surface beneath at the tip, 

 consequently the grasp is much less firm and secure, and their dexterity 

 in the use of this organ much less. The species of Cacajag have very 

 short tails of no use to their owners either to assist them in their 

 various movements, or for adornment. 



There is much difference in size among the American Monkeys 

 from the small Squirrel Monkey (Saimiri) and the Douroucouli 

 (Actus), to the Howlers (Alouatta) the largest species in the New 

 World. These last are remarkable for the great development of the 

 mandible especially of the angle and ascending ramus, particularly 



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