96 



NEW YORK STATE MUSEUM 



As in Circus, so too in the Buteos the scapular process of the 

 coracoid fails to reach the head of the clavicular limb, and this is 

 mentioned here because later on we will find that in some of the 

 Falconidae it does thus constitute a good character. Others have 

 the posterior end of the clavicular head making a more extensive 

 articulation with the anterior end of the corresponding scapula; this 

 character is fairly good but more variable. 



I have examined a complete skeleton of an adult male specimen 

 of U r u b i t i n g a a n t h r a c i n a and find that the characters 

 it presents agree almost exactly with the corresponding ones as we 

 find them in any of the typical Buteos. It would be extremely diffi- 

 cult to find good osteological characters to separate Buteo and 

 Urubitinga, generically. It can not be done with the material I have 

 at hand at this writing. 



Asturina p 1 a g i a t a and the several species of Archibuteo 

 all substantially repeat the osteological characters of the Buteos. 

 Careful examination has been made of all of them from ample, 

 as well as excellent, material. 



From these buteonine types we now pass to the consideration of 

 the osteology of some of our eagles. Of these, one that offers an 

 instructive skeleton is the Golden eagle (Aquila chrysae- 

 tos), and this chiefly from the fact that it so closely resembles the 

 skeleton in some large Buteo. In the matter of its skull it barely dif- 

 fers, except in point of size, from the skull of Buteo 1 i n e a t n s . 

 With the eagle the top of the cranial region is simply flatter (being 

 nearly in the same plane with the superior surface of the nasal 

 processes of the premaxillary) ; the maxillopalatincs are hardly in 

 contact in the middle line, nor do they fairly touch the septum 

 narium posteriorly ; these structures are further coated over with 

 a thin coat of compact tissue of bone, upon their nether and 

 mesial aspects ; the vomer does not rest upon them in front at its 

 apex ; the nasal septum may be slightly deficient between the nos- 

 trils, a small vacuity being present in it. Beyond these there are 

 no differential characters worthy of the mention in these two skulls, 

 and in their forms they are wonderfully similar, the Buteo's skull 

 being the very miniature of the eagle's. These cranial similarities 

 are extended to the remainder of the skeletons of these birds, and 

 in their characters they in reality correspond, one of the only dif- 

 ferences seen being a variation in the proportionate lengths of 

 some of the long 'bones. In the eagle, for instance, the tarso- 

 metatarsus is relatively considerably shorter than it is in the hawk. 



