xv, i Shufeldt: The Monkey-eating Eagle 47 



of the xiphoidal foramina, and that border presents a squarish 

 prolongation of no great size in the middle line; it possesses all 

 the other aquiline characters of this bone. 



In the bearded vulture, of Europe, the body of the sternum 

 is square in outline, and not a parallelogram as in eagles; its 

 coracoidal grooves do not decussate, and it has but six pairs of 

 costal ribs. In fact, the bone is that of a big vulture, and in 

 no way suggests that of an aquiline species of any sort. 



The pectoral limb. — Plates VII and VIII. It has long been a 

 well-known fact that all big raptorial birds possess limbs of great 

 size, power, and proportions. This is what we would usually 

 look for when we come to consider their habits and the character 

 of their prey. It also explains the fact that most of the bones 

 of their limbs enjoy a very perfect state of pneumaticity; the 

 skeleton of the foot, however, often forms an exception to this 

 condition. Possibly, in some of our eagles, even the foot bones 

 may be pneumatic; they appear to be so in some degree in our 

 white-headed species, but surely not in the golden eagle. True 

 vultures, almost without exception, possess a skeleton presenting 

 a lightness and an extremely perfect pneumaticity unequaled 

 by any other family of birds. Gypaetus forms a partial excep- 

 tion to this rule, in so far as the skeleton of its feet is concerned ; 

 but this bearded species approaches the eagles, while our Amer- 

 ican vultures are birds that practice long-sustained and steady 

 "flight, and do not capture their prey — hence a more perfect aera- 

 tion has evolved in them. 



In the different species of eagles, in so far as I have examined 

 them, the humerus varies but little in form or in general char- 

 acters. It is invariably a large and thoroughly pneumatic bone, 

 and to this statement Pithecophaga presents no exception. It 

 has a length of about 20 centimeters ; and, taken as a whole, its 

 shaft presents the "sigmoid curve" in a nearly perfect degree. 

 Rather less than its middle third is very smooth and quite cy- 

 lindrical in form. Its radial crest is short and triangular in 

 outline, while the ulnar tuberosity is very conspicuously de- 

 veloped and arches over — to some considerable extent prox- 

 imally — the deep pneumatic fossa, in which may be seen the 

 pneumatic foramina of very large size, but generally few in 

 number. There is also a row of these foramina along the base 

 of the smooth, elliptical head of the bone on the anconal side; 

 they are of no great size in this locality. A very distinct elon- 

 gate elliptical area — raised above the general surface — with its 

 major axis parallel to the bone's shaft, may be seen at the distal 



