^"i^'^^-] SHUFELDT, Skeleton of W'edoe-tailed Bcujle. 299 



and strong, and this is especially true of the part where it joins 

 with the remainder of die bone above it. 



In the Wedge-tailed Eagle, the lacrymal and their accessory 

 pieces are likewise large and massive in character, the latter being 

 thoroughly performed in bone as in Pithecophaya, while in Gol- 

 den Eagles and the Kamchatkan one this accessory piece may 

 long remain in cartilage. 



As is the case with nearly all the rest of the skull, the lacry- 

 mals are highly pneumatic in character. 



Uroaetns audax, in common with other Eagles, possesses a 

 large, quadrilateral pars plana; it is completely ossified, pneu- 

 matic, and stands out sub-perpendicularly from the mesethmoid 

 on either side. In no Eagle examined by me does it come in 

 contact with the lacrymal of the same side. 



Eagles, as a rule, i)ossess enormous orbital cavities, and to this 

 the Wedge-tail forms no exception. Their great size accounts 

 for the crowding backwards the cranial brain cavity, w^hich, in 

 the case of any of the species, is reduced to its minimum capacity 

 for birds of their size. IJoth the Kamchatkan Eagle and the 

 Monkey-eating one possess remarkably small brain cavities for 

 the size of the skull ; indeed, in an Eagle skull every part of 

 the bony structure seems to be in a way subordinated to the 

 necessity for possessing capacious orbital cavities. Either eye, 

 too, has in its make-up a wonderful circlet of sclerotic plates, 

 and these, in very old Eagles, may fuse into one solid ring. ( PI. 

 iii.. Fig. 6). When this happens, the sutural lines are almost 

 entirely obliterated. 



As to the strong, bony intcrorbital septum, present in all 

 Eagles, it is, in our present subject as well as in Pithecophaya, 

 Haliaetits, and Aquila, centrally perforated by a good-sized, 

 elliptical vacuity ; while in the Kamchatkan species the septum 

 is entire and very solid. As a matter of fact, in all Eagles the 

 orbital cavities possess osseous walls of more or less density on 

 all sides but the outer one, and this renders it a simple matter 

 to detect the usual foramina entering or passing out of an orbit, 

 for their definition in any case is clear. 



Up to this point of our comparison, no very distinctive charac- 

 ters have been discovered, which can, with certainty, be em- 

 ployed to distinguish the skull of Uroaetns from the skull of 

 some other Eagles of a similar size. To be sure, the big Philip- 

 pine bird can be thrown out, as its superior mandible distin- 

 guishes it at once.i: Turning to the Kamchatkan Eagle, its skull, 

 as compared wdth our present subject, may at once be recog- 

 nised by its superior size ; by the absence of any vacuity in its 

 interorbital septum, and by a few other insignificant characters. 



In the Golden Eagle the nasal septum is perforated, and the 



t Shufeldt, R. W. "Osteological and other notes on the Monkey-eating 

 Eagle of the Philippines, Pitliecoplia,^a jeffreyi. Grant." Philippine Journal 

 of Science, vol. xv., No. 1. Manila. P.I.. July. 1919, pp. 31-58. Pis. I. -XL 



