242 



NATURAL HISTORY. 



bones of the brain-case form with them a distinct joint, and so allow of that large amount of vertical 

 movement which will have been observed in these birds. The pre-maxillary bones (/>m), which are 

 so small in mammals, are very largely developed in birds, giving off, as they do, three processes : one 

 to the frontal bone (or fore-bone of the brain-case), one along the hard palate, and another externally 

 to form the margin of the beak. The parts that vary most in this bone-group are the bones which 

 make up the hard palate. Of these, the chief are the so-called palatines (p) and the maxillaries ; the 

 former are united by an articular surface with the bone which forms the anterior part of the base of 

 the brain-case, while there is in the middle a narrow bone, which, from its shape in man, has received 



the name of the vomer (plough- 

 share, v). The maxillary bones de- 

 velop hoi-izontal plates, which have 

 the palate below and the nasal 

 chamber above them.* 



The lower jaw (ma) is com- 

 posed of six pieces of bone on each 

 side the dentary, angular, sur- 

 angular, coronoid, splenial, and 

 articular. The upper part of the 

 joint is concave. 



The tongue is in relation, as 

 regards its support and movements, 

 to the hyoid bones, which will be 

 especially noticed in describing the 

 Woodpecker. 



Turning to the vertebral column, 

 we find a number of small bones, 

 complicated in form, and more or 

 less movable on one another. For 

 convenience of description they may 

 be divided into those which belong 

 to the neck (cervical vertebrae), to 

 the trunk (dorsal vertebrae), to the 

 sacrum (so-called because it was 

 SKULL OF YOUNG OSTRICH FROM ABOVE (A) AND FROM BELOW (B). offered in sacrifices !), or to the tail 



(After Owen.) 



(of) Occipital foramen; (so) Supraoccipital; (eo) Exocclpital; (q) Quadrate; (pa) Parietal 

 (ip) Pti-rygold process; (/) Frontal; (e) Ethmoid; (n) Nasal ; (pin) Premaxillary ; (m) Malar 



(p) Palatine ; () Vomer; (im) Intermaxillary; (I) Lachrymal bones. 



(caudal vertebra}). As has been 

 observed already, the first of these, 

 or the region of the neck, is very 

 long, and is always long enough for the beak to be able to reach to the base of the tail. In birds, 

 unlike mammals, the number of these cervical vertebrae may be as low as nine, or as high as 

 twenty-four. The first of them, which is known as the atlas, has on its front face a rounded 

 cavity into which fits the single projecting condyle, which was spoken of as being found at the back 

 of the skull ; and this condyle, being well rounded, is easily able to turn in the cavity which it fits, 

 and the head is thereby capable of a large amount of movement. In the succeeding vertebrae it is 

 possible to make out a body, an upper arch, through which passes the spinal cord, which meets above 

 in the middle line, and is produced into a more or less long spinous process set horizontally to the 



* These plates may become united with one another in the middle line, and the birds that possess this arrangement have 

 been called Desmognathce (de<r/io<;, ''a, bond ;" luiOos, "jaw") ; or they may be separated by a more or less narrow cleft, in 

 which case the birds in which this is found are called Schizognathce (<rx<?<, "I cleave"). As a matter of fact, the term 

 Schizognathous is confined to those birds in which the above-mentioned vomer is pointed in front, while where it is truncated 

 the birds are called jEgithognalhce (aV0o, "a sparrow, "as the character is seen in these birds). In these groups, however, 

 the Ostriches, or running birds, which are distinguished by having no keel to their sternum, are not included ; nor in them is 

 the vomer narrow behind. This broad character of the hinder end of the vomer is seen also in one group of birds with a keeled 

 sternum the Tinamous which are consequently distinguished from other " Carinate "birds by the term Drcmceognathce 

 s, the Emu). 



