OJHE INTBENAIr SKELETON. 1 87 



bone, the palatine is also pushed forward. These simultaneous 

 forward thrusts, bead the apex of the upper jaw slightly upwards, 

 flexing the skuU where the nasals and lateral ethmoids join the 

 frontals. But this movement of the upper jaw is very much 

 more extensive in the Parrots, where a regular joint extends 

 across the skull just in front of the frontals, and facilitates that 

 extreme mobility of the upper part of the bill, which is so 

 evident when a Parrot eats. 



The Os Jiyoides or Hyoid. — This curiously shaped bone con- 

 sists normally of a central portion formed of two ossicles — one 

 in front of the other — and of two pairs of slender and more or 

 less elongated branches — called " horns " or cormrn. The front 

 part of the hyoid lies between and below the rami of the lower 



Fig. 153. 



Ic 



•ge 



Os ireoiDES or a Ckane. 



h, Basi-hyal ; g, glOsso-hyal ; gc, ge, greater cornua or thyro-byals ; 

 Ic; Ic, lesser cornua or cerato-hyals ; «, urohyaL 



jaw, with its cornua extending backwards and more or less up- 

 wards behind the head. It is entirely disconnected with the rest 

 of the cranial skeleton save by soft structures, except that some- 

 times (as in Woodpeckers) the apieps of the cornua are applied 

 to one side of the skull beneath the orbit or within the nasal 

 opening. 



The posterior of the two median bones is called the lasi- 

 hyal and is generally short and thick, but is sometimes slender ; 

 the anterior one is the glosso-hyal, and lies within the tongue. A 

 bony process which often projects, tipped with cartilage, back- 

 wards from the basihyal is called the uro-Tiyal,, and may be a 

 distinct bone. 



To either side of the front part of the basi-hyal a styliform 

 bone is generally articulated, and may be short or more or less 

 elongated. This and its fellow of the opposite side constitute the 

 " lesser horns," lesser cornua, or comieala, or cerato-hyals. A 



