24 



EVERS'S COMPARATIVE ANATOMY. 



TABLE OF THE VERTEBRAE IN BIRDS. 



Skull. — It has been already shown that the bones composing the 

 skull of the crocodile, and other cold blooded vertebrata, were not 

 consolidated till a late period of life, giving rise to some difficulty 

 in tracing a correspondence between their bones and those of a 

 higher order. A still greater difficulty is experienced in determining 

 the component parts of the head in birds ; for in them the bones of 

 the skull are anchylosed, and every trace of suture effaced at an 

 early epoch ; therefore, in order to accomplish their perfect separa- 

 tion, it must be undertaken at an early period of their existence. 



In the majority of birds, the head is articulated to the spine, by 

 means of a single hemispherical tubercle on the basilar process of 

 the occipital bone ; but in the penguin and ostrich, the condyloid 

 portions contribute to its formation, and the articulation is such as 

 to admit of very great freedom of motion. 



The occipital bone is originally composed of four pieces, basilar, 

 spinous and two condyloid. The temporal consists of the petrous, 

 squamous, and tympanic portions ; the last is movably articulated 

 to the inferior part of the squamous portion, and is sometimes called 

 osquadratum. The alae majores of the sphenoid bone remain a 

 long time separate, and are called interarticular, or omoid bones. 

 The remaining bones of the skull present no remarkable peculiarities 



