QUADKUMANA. 



213 



species, on the contrary, which possess ischial 

 callosities, the Gibbons among the rest, sleep 

 and repose themselves in a sitting posture, 

 with the arms folded across the knees, and 

 the head reclined upon the breast, or sup- 

 ported by the shoulder. The Cebince, in 

 which the ischial callosities are wanting, lie 

 down on the lateral surface of their body. 

 The sternum is separated in the Cebince into 

 as many segments as there are true ribs ; 

 consequently it has quite lost the analogy 

 with the human subject, which it has in the 

 higher monkeys of the Old World. In the 

 anterior extremities, the humerus of Cebus, 

 Nochthora, Saimiri, and Ouistiti, is similar to 

 that of the Carnivora, by an aperture in the 

 internal condyle, serving for the passage of 

 the brachial artery and the median nerve, 

 which are preserved in this manner from 

 compression and injury, by the contraction of 

 the muscles in the climbing motion of these 

 Quadrumana. In the carpus of the Cebincs 

 there are nine bones, and consequently they 

 possess the intermediate bone, proper, as I 

 have said, to all the monkeys, with the ex- 

 ception of the Chimpanzee. The phalanges of 

 the fingers and the toes are in general very 

 long and incurvated, by which disposition 

 they acquire a greater aptitude to grasp 

 branches of trees, while climbing. In Ateles 

 the fore-hand has quite lost its analogy with 

 the hand of man, by the want of the thumb, 

 which is only represented by an imperfect 

 metacarpal bone. In Ateles hypoxanthus, which 

 has a rudimental thumb, Prince MAXIMILIAN 

 says that it consists of two phalanges, of which 

 the first is but half as long as the second. In 

 the Cebi, the fore-hand differs from the hand 

 of man, by the deviation of the thumb, which 

 is situated on the same level as the other 

 fingers, and has the same length as the little 

 finger. The nails are elongated, and acquire 

 really the form of little claws in the Ouistitis. 

 The posterior extremities offer the general 

 character of the posterior extremities in the 

 monkeys ; the thumb of the hind hand is 

 distant, and has a flat nail in the Ouistitis, 

 while on the other fingers there are small 

 claws. 



NEUROLOGY. The brain of the Cebines 

 differs much in the various genera which are 

 referred to this, large division of Quadrumana. 

 In the Cebi it is perfect, and approaches much 

 to the brain of man, as may be seen in the 

 drawing given by TIEDEMANN in his excel- 

 lent work. But, according to the observa- 

 tions of I. GEOFFROY ST. HILAIRE and of 

 myself*, there are no circonvolutions on the 

 proportionally very large brain of the Ouistitis, 

 and there are but few in the Saimiri, in which 

 the anterior lobes are not so much developed 

 as in the Cebi. To these statements LEU RET f 



* Comptes Rendus, t. xvi. n. 23, 1843, 12 Juin, 

 p. 1236, and Description des Mammiferes Nouveaux, 

 etc., in Archives du Museum, torn. ii. liv. 4., Paris, 

 1841, p. 515. 



f Comptes Rendus, tom.xvi."n. 24 p.1372. LEUCK- 

 ART agrees with these observations of I. GEOFFROY 

 ST. HILAIRE, saying that he found scarcely any 



made some objections, which have been suffi- 

 ciently refuted by I. GEOFFROY ST. HILLAIRE. 



MYOLOGY. As respects the muscles, those 

 of the tail only deserve a special notice. 

 They are very strong, especially the flexor es. 

 By them the Ateles, if it is wounded to death, 

 remains a long time, hanging on his tail. For 

 the same cause its tail is always inflected 

 when in the state of rest. The Cebi sustain 

 their body on it, if they are forced to go on 

 their hinder legs. The other muscles seem 

 not to differ from those of the monkeys of 

 the Old World. The general description of 

 these may be applied to them. 



SPLANCHNOLOGY. The soft parts afford 

 no material for such interesting observations 

 as those of the monkeys of the Old World. 

 The larynx wants in general the pouches, 

 which I have described before. There are 

 but two exceptions yet known, one in the Ma- 

 rikina (Hapale rosalia), in which CUVIER and 

 CARUS state that they have found a laryngeal 

 pouch, which, according to CUVIER, communi- 

 cates with the larynx between the thyroid and 

 cricoid cartilages. The second exception is 

 the Ateles paniscus, in which there is a mem- 

 branous expansion behind the cricoid carti- 

 lage. The hyoid bone of Ateles has the 

 form proper to the monkeys of the Old 

 World. In Cebus it approaches more to the 

 form of man^ by a more truncated pyramidal 

 and a less convex or scutiform base. 



The disposition of the laryngeal apparatus 

 in the genus Mycetes deserves a more accu- 

 rate notice. It is distinguished, as may be 

 seen in fig. 134, by a peculiar tympaniform 

 dilatation of the base of the hyoid bone, by 

 which a repercussion of the exhaled air seems 

 to be produced. A great resonance, effected 

 by the elasticity of the parietes of this bony 

 cavity, must be the result of this repercus- 

 sion, by which the terrible howlings of these 

 animals are produced. 



Upon the other soft parts of the Cebince there 

 is nothing very particular to say. I mention 

 only the structure of the stomach in Ateles 

 and Mycetes, in which, according to the ob- 

 servations of CUVIER and of Prince MAXIMI- 

 LIAN, there is some tendency to the saccu- 

 lated form of the stomach in the Semnopitheci, 

 This peculiarity confirms all that I have said 

 before about the analogy between Ateles and 

 Semnopithecus. In the organs of generation 

 the length of the clitoris is worth notice, 

 particularly in Ateles and Cebus. According 

 to the observations of LEUCKART * it has an 



convolutions in the brain offfapale rosalia and^'ao 

 chus. Recently I. GEOFFROY ST. HILAIRE has showed 

 to the French Academy two brains of Ouistitis, and 

 has invited the members to verify the three state- 

 ments which he published, viz., "1'existence de 

 chaque cote d'un sillon profond transversal entre le 

 lobe cerebral anterieur et le lobe moyen ; celle de 

 quelques sillons lineaires et superficiels correspondant 

 au trajet des vaisseaux, et 1'etat lisse de la presque 

 totalite de la surface des hemispheres." Comptes 

 Rendus, n. 714, Aout, 1843, p. 280. 



* F. S. Leuckart, Zoologische Bruchstucke ; 

 Stuttgart, 1841, ii. p. 61. 



p 3 



