QUADRUMANA. 



of it the genus Chrysothrix. Its tail is not 

 prehensile, but depressed, and often twisted 

 round objects. Its head is flat ; between the 

 two orbits there is but a membranous septum, 

 instead of a bony wall, and the glans penis is 

 round, as in man ; while it is flat, in the form 

 of the head of a mushroom, in the Cebi, which 

 have the penis in continual erection. 



G. Sixth Genus. Nochthora F. CUVIER. 

 Aotus HUMBOLDT. Douj'ocouK. 



Differs only from the genus Callilhrix by large 

 nyctalope eyes and ears, which are partly co- 

 vered by the skin, and by a small face. The 

 species of this genus have nocturnal habits, 

 and a feline physiognomy. They feed not 

 upon fruit, as the precedent species, but on 

 small birds and insects. In their form, noc- 

 turnal habits, and great sensibility to light, 

 the Nochthorcc approach very much to the 

 species of the genus Stcnops, from which they 

 differ in their internal structure. Their nails 

 are straight, long, and sulcated. The dental 



f , . . . 4 .11 , 



formula is: incisors ..canines , molars 

 4 I 1 



(J Q 



They inhabit Brazil. 

 6 6 



Spec. Nochthora trivirgata. 



7. Seventh Genus. Pithecia. Saki. 



The characters of this genus consist in the 

 bushy, but short, prehensile, and long tail, the 

 slender body, the large ears, the dense beard 

 in some species, and the straight, but claw-like 

 nails. Their incisor teeth are more prominent 

 than in the genus Ccbus. Brazil. 



Spec. Pithecia Satcmas, P. nifivcntris, P. 

 leucocephala, P. inusla. 



8. Eighth Genus. Hapale. Ouistili. Salmi. 



This genus departs more from the typical 

 genera of monkeys of the New World than any 

 other, inasmuch as they have only the same 



number of teeth as the monkeys of the Old 



4 " i ] 



World,viz.32 : incisors - , canines - , molars 



T L I 



The nails, by being compressed and 



55 

 55' 



pointed, assume the appearance of claws, ex- 

 cept the thumbs of the after-hands, which have 

 flat nails ; but the thumbs of the fore-hands, 

 which have no flat nails, are so slightly sepa- 

 rated from the other fingers, that it is not 

 without hesitation that the Ouistitis are called 

 four-handed or Quadrumnnu. All the species 

 belonging to this genus live in troops in the 

 Brazilian forests, where they spring from 

 bough to bough, more like birds than quadru- 

 peds. They resemble squirrels, whose form 

 they seem to represent in South America, 

 which possesses but one species of squirrels, 

 Sciuriis (Estuans. Their incisors, canini, and 

 false molars, are sharp and acuminated. The 

 inferior incisor teeth are long, narrow, and 

 prominent. They feed upon insects, eggs, birds. 

 Their "voice is a gentle whistle, winch de 



211 



Humboldt* compares to the voice of some 

 birds. He says that their larynx is similar to 

 the inferior larynx of birds, but he did not 

 illustrate this opinion by sufficient anatomical 

 details. 



The species can be divided into two groups. 

 The first contains those in which the inferior 

 incisors are cylindrical and the tail is annular. 



Hapale jacc/ius, H. penicillatus, H. leuco- 

 ccphalus. 



In the second, the inferior incisors are 

 truncated like the mouthpiece of a pipe, and 

 the tail is not annular. 



H. argeutatus, H. midas, IT. wsuhis, H. 

 labiafus, H. chrysomelas, H. rosalia, H. 

 chrysopygus, H. ccdipus. 



OSTEOLOGY. If we take a general survey 

 of these eight genera of monkeys of the New 

 World, we may observe in them, as well as in 

 those of the Old World, an indication of the 

 descending line, by which they pass into the 

 form of the Lcmurince, and by those into the 

 Inscctirora. In this way they constitute a 

 series, which is parallel to that of the monkeys 

 of the Old World, the latter passing into the 

 Carnivora, the former into the Insectivora. 

 The truth of this assertion will be proved by a 

 more minute examination of the skeleton. 



We shall first consider the skull. J. A. 

 WAGNER divided the monkeys of the New 

 World by their skull into two great divisions. 

 The first is a pyramidal skull, in which the 

 height is greater than the length, and in which 

 the occiput has no posterior eminence, and 

 the occipital foramen is situated backwards. 

 To this division belong Mycetes, as eminently 

 characteristic, and, in subsequent gradation, 

 Callithrix, Nochthora, Pithecia, and Lagothrix. 

 The second form of skull is elongated, with a 

 prominent muzzle, a convex occiput, and an 

 occipital foramen, situated at the basis of the 

 skull. WAGNER refers to it the Sainriri, offer- 

 ing a typical pre-eminence, and subsequently 

 Ilfipale, Cebus, and Aides. 



In Mycetcs (fig. 132) the forehead is ele- 



Fig. 132. 



Skull of Mi/celcs ursinus. {Original, 3 fun. ]"/<>////.) 



vated, the face flat and large ; the distance 

 between the two orbits very great; two nasal 

 bones ; the chin very depressed ; the lower 

 jaw high, with distant branches, between 



* A. do Humboldt, Observ. de zoologio et d'ana- 

 tomie comparec. Paris, 1811, vol. i. i>. K. 



