9 8 



NEW YORK STATE MUSEUM 



with the Golden eagle, but beyond that we find in the former, that 

 the skull is considerably lengthened ; the superior osseous mandible is 

 ponderous ; neither the orbital nor the nasal septum show any vacui- 

 ties in them ; the horizontal part of a lacrymal is not as large, though 

 the accessory pieces are well developed in both ; the conduit for the 

 first pair of nerves through either orbit, may be more or less covered 

 over with bone (they are open and double for their entire length in 

 Aquila) ; there is a more general fusing of the nasal septum and 

 maxillopalatines, anteriorly ; the vomerine plate shows many de- 

 ficiencies in it ; the palatines are more massive, and finally, the 

 summation of these points will at once be- sufficient to distinguish the 

 skull of the White-headed eagle from the skull of its more buteonine 

 congener- — the Golden eagle. Either of them may have the an- 

 terior walls of the Eustachian tubes entirely unprotected by bone, as 

 we found it in some of our Cathartidae. 



Some very excellent distinguishing characters are to be found in 

 the trunk skeleton, and skeleton of the limbs in" Haliaetus, for its 

 sternum is usually entire at its xiphoidal extremity, rarely showing a 

 •small foramen upon one or the other side, and the keel of this bone 

 is not produced posteriorly to the xiphoidal margin by some con- 

 siderable distance [pi. n, fig. 25]. 



In the pelvis, six of the anterior sacral vertebrae throw out their 

 processes upon either side against the nether surface of the ilium ; 

 only five in the Golden eagle. Posteriorly, four of the vertebrae are 

 modified with their parapophyses produced and their extremities 

 fused.; there being but three in the Golden eagle. Again in the 

 White-headed eagle the obturator foramen of the pelvis is always 

 closed in by the postpubis, which extends some distance behind it; 

 and further the postpubic may not be " interrupted " in the eagle. 

 Now in Aquila the obturator foramen is never completed by this 

 pubic spine, and an interval always occurs, as in the Buteos. 

 Finally, the postacetabular portion of the pelvis in Haliaetus is not 

 bent downward and forward as much as it is in the Golden eagle, 

 and the bone as a whole is considerably larger. 



The sternum in Aquila is much like a large Buteo's sternum, and 

 usually has a big foramen upon either side of the carina, well out 

 toward the lateral border. The coracoidal grooves decussate. 

 Seven facets are found upon either costal border [pi. 15, fig. 31]. 



Aside from the difference in size, and the larger skeleton of 

 Haliaetus, there remain but few noteworthy differences in the 

 skeletons of these two eagles. In Aquila the posterior extremities 



