202 



QUADRUMANA. 



four-footed Mammalia. The same analogy 

 with these appears in the disposition of the 

 lumbar vertebras. Their number is six or 

 seven, and their articular or oblique processes 

 are bifurcated, and give origin to a styloid 

 process, which serves to increase the strength 

 of the lumbar part of the vertebral column, 

 and is therefore to be found in the greater 

 number of the quadrupeds, 



There is no true sacrum ; but two or three 

 sacral vertebrae, forming a conical series, are 

 separately united to the iliac bones, in the 

 same manner as in the Carnivora. The pelvis 

 is much more elongated and cylindrical than 

 in the Chimpanzee, and consequently more 

 approximate to the type of the quadrupeds. 

 The iliac bones are very long, but narrow, 

 with a posterior concave, and an anterior 

 convex surface. The pubic symphysis is very 

 long ; the ischiatic tuberosities are curved 

 outwards, broad, and form a semicircular 

 surface for the insertion of the ischial callo- 

 sities, which serve the Mandrills as a secure 

 and commodious seat, when they are disposed 

 to sleep or repose after the violent and fa- 

 tiguing motions which they habitually exe- 

 cute. By all these peculiarities it is manifest 

 that the Mandrill is much more remote from 

 man than the Chimpanzee, and a superficial 

 examination of the two skeletons (figs. 121 and 

 122) will be sufficient to show the great differ- 

 ence existing between them. 



Between these two extremes are ranged the 

 other genera of Monkeys of the Old World, as 

 I have stated in the above-mentioned book. 

 I take the liberty to refer to it for more details, 

 and principally for the gradual deviation, by 

 which the vertebral column of the Chimpanzee 

 passes, by the intermediate forms of the Orang- 

 cetan, the Gibbons, the Scmnopitheci, the Inui, 

 to that of the Cynocephali ; but I think it 

 necessary to make an exception for the Sia- 

 mang, because the anthropo-morpJwus disposi- 

 tion is more distinct in this ape than in any 

 other, and even more than in the Chimpanzee 

 or Orang-cetcin. The ascending processes of the 

 superior surfaces of the bodies of the cervical 

 vertebra; ; the inclination of the spines from 

 the fourth to the ninth dorsal vertebra? ; the 

 number of five lumbar vertebras ; their in- 

 creasing strength and breadth backwards ; the 

 form of their transverse and spinal processes ; 

 the true sacrum, and the quite anthropo- 

 morphous disposition of the iliac bones, make 

 the vertebral column of the Siamang (as may 

 be seen mfig. 123) approach the most to that 

 of man. The same conformity with man ap- 

 pears in the sternum of the Siamang. It is 

 composed of the same portions as the ster- 

 num of man, viz. the manubrinm, the body of 

 the bone, and the xyphoidal appendix ; but it 

 is proportionally broader and shorter, and the 

 body consists of two symmetrical parts. In 

 the sternum of the Chimpanzee there is more 

 analogy with the structure in inferior ani- 

 mals. It has a separate manubrium, want- 

 ing the semi-lunar incision of that of man. 

 It is connected with a series of osseous seg- 

 ments, and with a xyphoid appendix. In the 



Orang-cetan all these segments, and some- 

 times also the manubrium, are separated in 

 two symmetrical parts. Consequently it offers 

 the division proper to the sternum of man, in 



Fig. 123. 



Skeleton of the Siamang. (Original, Mus. Vrolik.) 



the earliest periods of foetal life, but con- 

 tinuing to exist sometimes by deformity, as 

 has been proved by Otto* and Breschet.-f- 

 In the other Monkeys, and principally in the 

 Mandrill, there is no conformity at all with 

 the sternum of man. The manubrium is 



* Otto, in the above-mentioned pamphlet, 



f G. Breschet, Eech. sur diffe'rentes pieces du 



Squclette des Animaux Verte'bres; Ann. de Sc. 



Natur. Aout, 1838. 



