ORGANS OF SUPPORT, 



FIG. 39. 



beneath them. These two bones are thus early united in 

 most other reptiles, in all birds, and in the greater number 

 even of the mammalia, although they are separate in the 

 normal form of the human skull. 

 This condition of the two pari- 

 etals is the more required in 

 serpents, from the loose state of 

 most of the other bones of the 

 head, and the exposure of these 

 animals to the trampling of qua- 

 drupeds, and other dangers while 

 they lie concealed in their natu- 

 ral haunts. The anchylosis of 

 the two parietal s gives greater 

 security to the strong temporal 

 muscles of these animals, as in 

 other classes, where this solidity 

 of attachment is required. From 

 the length, and the loose attach- 

 ment of the squamous portion (e } ) 

 of the temporal bone to the parietals, the tympanic bone (/,) 

 and consequently the lower jaw (#,) has much greater ex- 

 tent of motion in a lateral direction. The two anterior (i, i,) 

 the two middle (h, h,) and the two posterior (k, k,) frontals 

 remain detached, and form, as in other reptiles, the greater 

 portion of the front of the skull. The great breadth of 

 the two lachrymal (/, /,) and of the two nasal (p 9 p 9 ) bones 

 corresponds with the general flat and broad form of the 

 head of serpents. The two upper jaw-bones (m, m,) and 

 the two intermaxillaries (q,) are separate and quite moveable 

 on the surrounding bones ; and the two palatines are also 

 moveable and long, and support the most permanent teeth 

 of these animals. The two sides of the lower jaw are quite 

 detached from each other, and freely moveable at the sym- 

 phesis, and the pieces of which it is composed are also 

 moveable. This freedom of motion of the lower jaw (g, t/ 9 ) 

 extends through the long tympanic (/,/,) and squamous 

 (e, <?,) elements of the temporal bone to its more fixed 

 petrous portion (</,) so that the mouth is here capable of 

 extraordinary dilation, to transmit through its cavity entire 

 prey, which the serpents have not the means of dividing. 



