416 QUADRUMANA. 



Siamang, has the larynx furnished with a sacculus. This point, however, 

 must not be insisted on; our acquaintance with the anatomy of these 

 animals being but partial. There are no cheek-pouches. 



In all the individuals yet examined (viz., the H. leuciscus, by Camper ; 

 the S. Lar, by Daubenton, see Buflfon, xiv., pi. iv. p. 108 ; and the H. 

 agilis, by Mr. Yarrell, see Zool. Journal, vol. v. for 1835 ; the H. Hoo- 

 lock, and H. concolor), the vermiform appendix to the caecum was present. 

 In their osseous structure the Gibbons resemble the Orang, excepting 

 that the bones are more slender, and the skull is of a different form, com- 

 paratively smaller, and of a less solid construction. The cranium (fig. 

 273) is somewhat of an oval figure ; the forehead retreats, almost as in the 

 Chimpanzee, but the supra-orbital ridge is not prominent, as in that animal ; 

 273 nor does the skull exhibit the elevated 



crests so remarkable in the Great Pongo. 

 The occipital portion of the cranium is 

 far more voluminous than the frontal, which 

 is both low and narrow. The orbits are 

 very large, with a prominent margin ; and 

 the interorbital space is depressed and broad, 

 averaging half an inch, and throwing the 

 of Gibbon. orbits apart, so that their outer margin 



projects very boldly from the cranium. The nasal bone rises gently from 

 its junction with the frontal, exhibiting an attempt at a bridge, in which 

 respect it approaches far more nearly to the human form than it does 

 either in the Chimpanzee or Orang. In one specimen (adult) the Author 

 found the nasal bone partially divided by a longitudinal suture. The 

 osseous aperture of the nares is wide and oval. The upper jaw is not large 

 or prominent, as in the Orang ; and the rami of the lower jaw are remark- 

 ably narrow r , deepening at the symphisis, which is vertical (not retiring), 

 so as to form a tolerable chin, at least, for a Monkey. The superficies of 

 the coronoid process, indeed the whole space for the lodgment of the 

 masseter muscle, is very inconsiderable ; the posterior angle is acute, 

 and more or less produced, instead of being rounded ; the incisors are 

 small, moderately oblique, and thick ; the canines are slender, but long, 

 especially in the males ; the molars are small, with the crown broad, and 

 bluntly tuberculate ; there is no true fifth tubercle on the last molar 

 below ; the humerus is straight, or with a very slight twist ; its head is 

 large ; the radius and ulna are both very long and slender ; the femur is 

 straight ; the tibia arched and compressed, with an acutely-elevated anterior 

 ridge ; the fibula is very slender ; the pelvis is peculiarly long and 

 narrow ; and the tuba ischii flat and rough, indicating the presence of the 

 callous pad which covers it ; the clavicles are long, and rather simply 

 curved than sigmoid ; the scapulae are long and narrow ; the ribs are 



