302 SHUFELDT, Skeleton of IFedi/e- failed Ecujle. [\^,^l^^x 



toral arch, sternum, pelvis, and so on. It requires but a very 

 superficial comparison to find this to be the case with respect 

 to the trunk skeletons of the several species of Eagles at hand. 

 In each and every one of these, including the subject of the pre- 

 sent contribution, we find fourteen cervical vertebra, the last 

 two (13th and 14th) bearing each a j^air of free ribs (very rudi- 

 mentary on the 13th vertebra). There are five dorsal verlebrje, 

 all having ribs connecting with the sternum through co.-.tal ribs. 

 There are two pairs of pelvic ribs, and both i)airs connect with 

 the sternum through costal ribs. All these dorsal and pelvic ribs, 

 save the last i)air of the latter, support large, elongate, epipleural 

 a[)j)endages, in each case being solidly anchylosed to the border 

 of the rib. Costal ribs are also stout, the first pair being the 

 shortest, the remaining ones becoming longer and longer as they 

 advance from before, backwards. 



For a side view of the Eagle pelvis, see Plate iv., Fig. 7, and 

 for a dorsal view of the bone in the Golden Eagle see my "Oste- 

 olog}^ of Birds" (P. 97, Fig. 48) ; it is fully described in my 

 ]>aper on PithecopJiaya (autea, p. 40). There are eight caudal 

 vertebrae, plus a large pygostyle. 



There is but little variation in the case of the bones of the 

 shoidder-girdle among any of the true Eagles, and this applies 

 to the various species at hand at this writing. The coracoids are 

 stout and large; the as furcida is a big, wide-spreading U-shaped 

 bone, and the scapulae are broad and long. (Sec Pis. i\-.-\i. of 

 the PiihecopJiacja memoir; PI. iv., Fig. 7 of this ])aper. and 

 several figures in my Osteology' of Thirds.) 



There is a great similarity in the case of the sterna of Eagles, 

 and this, too, applies to the bone as we find it in Uroaetns, AquUa, 

 Pithecophaga, Haliaetus and Thalassoaetus. It is twice as long 

 as broad; dorsally it is deeply concave, and corres]iondingly 

 convex ventrally ; the keel is more or less deep anteriorly, but 

 becomes gradually shallower from before, backwards ; it is lost 

 on the body of the sternum, far in advance of the transverse, un- 

 notched .xii)hoidal border; the anterior carinal border is concave 

 from the small, trihedral manubrium to the carinal angle; the 

 coracoidal grooves decussate in the median line. There may 

 or there may not be an elliptical foramen on either side, far 

 back on the xiphoidal i)art of the bone, and more or less near 

 the outer angle ; these foramina vary in size, and they may be 

 entirely absent, or there may be only a single, small one on one 

 side or the other. As a classificatory character, these foramina 

 are valueless, as their presence or absence may obtain in birds 

 of the same species, either upon one side, or both. The entire 

 trunk skeleton is pneumatic, save more or fewer of (he distal 

 caudal vertcbne. 



Apart from the presence or absence of the xiphoidal fora- 

 mina, the sternum of Uroaetns is almost identical in a4 of its 

 characters with that bone in HaUaetus — size included. While 



