CALLITHRIX JACCHUS, THE MARMOSET 155 



extending its range as far as Bolivia, another being indigenous to Colomljia. 

 There are records of CaUithrix jacchus having also been found in the island 

 of Marajo, lying between the mouths of the Amazon and Para Rivers. 

 The marmoset has a black face with white spots. There arc cross-bands 

 on the back and tail. The animal lives in the tree tops or smaller underbrush. 

 The claws upon its feet and hands enable it to climb along the limbs and up 

 the trunks of trees much in the manner of a squirrel. It has a cat-like agility 

 but does not make long and daring leaps like the lemur. It often loses its 

 hold upon the branches and falls from considerable heights to the ground 

 without sustaining apparent injury. For this reason, and perhaps because 

 of its small size, it is not in need of the extreme degree of prehensile power 

 in either fore- or hindlimbs. It may also be because of this fact that its tail 

 has failed to develop prehensile qualities. While in captivity it shows little 

 tendency to acquire reactions which it does not already possess in the free 

 state. It does not lend itself to training or the acquisition of tricks, as do 

 many of the other anthropoid forms. The animal lives upon worms, insects 

 and fruits. It is known also to invade the nests of birds and suck the eggs. 

 Only exceptionally, however, does it prey upon bird-life, and in such exceptions 

 it may occasionally be able to overpower one of the smaller birds or unpro- 

 tected young. It has little of the acquisitive celerity manifested by the lemur. 



Measurements and Indices of Callithri.x Jacchus 



Total length of the animal 510 mm. 



Length of the tail 295 mm. 



Length of the foot 61 mm. 



Diameters of the skull 



Occipito-nasal 42 mm. 



Bitemporal 22 . 5 mm. 



Length of the brain case 35 mm. 



