THE AECTOPITHECINI. 463 



furred, long-tailed, habitually quadrvipedal. Squirrel-like, 

 animals, which are found only in South America. jSTone 

 of them are provided with cheek pouches, nor possess bare 

 and callous patches of integument over the ischia. The 

 ears are lai-ge and hairy, and the nose is flat and broad, as 

 in the Platyrrlvini. 



The fore limbs are shorter than the hind lirubs. The 

 pollex is not opposable, nor susceptible of extensive abduc- 

 tion from the other digits, which it resembles in being pro- 

 vided with a shai'p curved claw. The manus, conse- 

 quently, is a mere paw, and the term " hand " is not appli- 

 cable to it. The hallux of the foot is very small and is pro- 

 vided with a flat nail. The nails of all the other digits of 

 the pes are falcate. The plantar surface is very long, and 

 the digits are vei-y short. It follows from these facts that 

 the term " quadnimanous " is not applicable, in any sense, 

 to the Marmosets. 



The skuU. is remarkable for the smooth and rounded 

 surface and relatively large size of the brain-case. 

 Although the orbits are large, the brow ridges are incon- 

 spiciious, and the occipital region of the skull projects so 

 far backwards that the occipital foramen may lie com- 

 pletely upon the under sui-face of the skull, towards the 

 junction of its middle and posterior thirds ; and have its 

 plane almost horizontal, when the face looks forwards. The 

 orljit is almost completely shut off from the temporal fossa 

 by ]3one. 



The hyoid resembles that of the Lemurs, its body being 

 narrow and much arched from side to side, while the anterior 

 eornua are strong. 



There are iisually nineteen dorsolumbar vertebrae, and 

 the transverse processes of the atlas are somewhat broad 

 and flattened. 



2*2 1 1 3*3 '>*2 



The dental formula is i. ■;—, c. - — - n.m. -— n. ^ = 32. 



Thus the number of the teeth is the same as in Man and the 

 Catarrhini ; hut in the number of the premolars and molars 

 the A)xtopithecini difi'er from both the Catarrhini and the 



