THE ARCTOPITHECINI. 393 



The fore-liinbs are shorter than the hind-hmbs. The pol- 

 .ex is not opposable, nor susceptible of extensive abduction 

 from the other digits, which it resembles in being provided 

 with a sharp, curved claw. The manus, consequently, is a 

 mere paw, and the term " hand " is not applicable to it. 

 The hallux of the foot is very small, and is provided with a 

 flat nail. The nails of all the other digits of the pes are fal- 

 cate. The plantar surface is very long, and the digits are very 

 short. It follows from these facts that the term " quadrumar 

 nous " is not appUoable, in any sense, to the Marmosets. 



The skull is remarkable for the smooth and rounded sur- 

 face and relatively large size of the brain-case. Although the 

 orbits are large, the brow ridges are inconspicuous, and the 

 occipital region of the skull projects so far backward that the 

 occipital foramen may lie completely upon the under surface 

 of the skull, toward the junction of its middle and posterior 

 thirds ; and have its plane almost horizontal, when the face 

 looks forward. The orbit is almost completely shut off from 

 the temporal fossa by bone. 



The hyoid resembles that of the Lemurs, its body being 

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

 cornua are strong. 



There are usually nineteen dorso-lumbar vertebra, and the 

 transverse processes of the atlas are somewhat broad and flat- 

 tened. 



The dental formula is i. j— j c. ^^ p.m. 3T3 »i. 2T5 = 33. Thus 



the number of the teeth is the same as in man and the Catar- 

 rhini ; but in the number of the premolars and molars the 

 Arctopithecini differ from both the Gatarrhini and the Platyr- 

 rhini, having one premolar more than the former and one true 

 molar fewer than the latter. In Sapale, the lower incisors 

 are proclivous ; and the canines are approximate to them, and 

 similarly inclined, as in the Lemurs. 



Although the manus is a paw and the pollex is not oppos- 

 able, this digit has its proper abductor, adductor, and long 

 and short flexors. The existence of a proper opponens of the 

 pollex is doubtful, but there is an opponens minimi digiti. 

 The flexor longus is completely united with ihe flexor pr<yfunf 

 dus digitorum, but the tendon for the pollex comes off on the 

 radial side instead of on the ulnar side, as it does in some of 

 the higher SimiadoB. The extensor seoundi internodii pollicia 

 is united with the extensor indicia, and the extensor minimi 

 digiti gives oflF slips to the third, fourth, and fifth digits, so that 



