The Skull loo 



know them by then- position relative to the hrain open- 

 ing; the upper edge of the hole is Mlvvays formed Iniht; 

 supraoccipital, the lower by the basio('(*ij)ital, the two 

 sides by the exoceipitals. 



Although many l^ones of the skull, such as the supra- 

 occipital, keep their names, whether found in saln:on, 

 frog, lizard, bird, or man, others identical in posh ion 

 have had new names given them. For instance, a small 

 bone directly in front of the eye is known as the lacrymal, 

 from its close relation to the tear-duct, l)ut in hshes the 

 bone is called the preorbital, as a suggestion of hsh-tears 

 would be rather absurd. 



We may find the dried ear-drum, or tympanum, 

 stretched tight across the entrance of the car-('a\ities, 

 and if we break this, or even look carefully through the 

 transparent membrane, a long thin bone may be secMi 

 beneath, extending backwards from the under surface of 

 the drum. This is the columella, or little colunm of 

 bone, and will have an interest for us later on. 



/If we examine the way in which the u|)})er and lower 

 mandibles or jaws are joined to the skull, we will find a 

 very ingenious arrangement; one very different from 

 that in ourselves. If the l)eak of a bird is to serve as 

 hand, lips, and mouth, it must be as free and movable as 

 possible, and instead of the upper jaw being fixed im- 

 movably to the skull, and the lower jaw swinging uj) 

 and down from it. we find that the u})per jaw is attached 

 very loosely, while each side of the lower mandible hinges 

 upon a loose irregular-shaped bone, known as the quad- 

 rate. A long slender bone connects the quadrate with 



