OSTEOLOGY OF BIRDS 



217 



a fact that can be accounted for by the former being obliged to use 

 its brains more than the latter. 



Upon lateral view of these two typical skulls we find for com- 

 parison but three points that demand our special consideration; 

 these are, the arch of the superior margin of the orbit; the depth of 

 the parietal region; and, the interorbital septum [fig. 36, 37]. 



First, as to the arch of the superior margin of the orbit, we find 

 this more elevated, and, as it were, more convexed in the wild than 

 it is in the tame turkey, where this arc is depressed, long and 

 shallow, and but slightly raised above the plane of the frontal 

 region. 



Another very well marked character and one rarely departed 

 from, is the depth of the parietal region ; what I mean by this is 



Rear views, natural size, of the skulls of the wild [fig. 34I and tame [fig. 35] 

 turkeys, f, frontal bone; p. parietal; pf, postf rontal process; qj. quadratojugal; q, 

 quadrate; fin, foramen magnum; and oc, occipital condyle. In both specimens the 

 mandibles have been removed. 



the distance measured on a median longitudinal line from the 

 parietal prominences to the occipital ridge. This line is proportion- 

 ately much shorter, and less horizontal in the wild turkey than it 

 is in the domesticated one. By the aid of this character alone, I 

 believe I could in a mixed collection of these two species of turkey, 

 correctly pick out the skulls of the vast majority that belonged to 

 either kind. This difference is indicated by x in figures 36 and 37. 



As to the condition of the interorbital septum I would say that, 

 in all the specimens of M . g . merriami, which I have ex- 

 amined, this bony plate is entire and of considerable thickness. I 

 have found this to be the case in but one instance in the series of 



