772 \ GEOLOGICAL SURVEY OF THE TERRITORIES. 
lower border of the keel is convex; the front border concave; their angle of union 
rounded off. The instances where the sternum is entire have been cited; in other 
birds of prey the arrest of ossification is 
limited to very small parts of the hind 
border, usually a foramen, rarely a notch 
(Sarcorhamphus) on each side, one of which 
may be filled up, wholly or partially. 
Eyton figures two small notches on each 
side of the posterior border in Hierax 
bengalensis; and both hole and notch on 
each side in Cathartes aura. 
In our specimen of Sarcorham- 
phus gryphus a faint indentation 
marks this posterior border on each 
' side, but in Pseuwdogryphus two well- 
defined notches of equal depth are 
Cathartes aura, No.692 in the Smithsonian Institution. observed on either side of the keel. 
Eyton states for the South American Condor : 
Sternum:— * * * Posterior margininayoung bird with two indentations, which 
are nearly obliterated in the old one.—(Osteologia Avium, p. 18.) 
Mr. F. A. Lucas, who kindly ex- 
amined the specimens of the Old 
World Vultures in the Natural Sci- 
ence Establishment at Rochester for 
us, writes me that, ‘ You will notice 
that the right sternal foramen of 
| Neophron is closed (referring to a 
specimen sent to the Army Medical 
Museum); this was also the case 
with a second specimen, while a 
third, somewhat younger, had the 
foramen open, but much smaller 
Catharista atrata.—Specimen from Florida. than the left. A specimen of We- 
ophron from N. India has both foramina open, and there are a few 
trifling differences between its skull and that of the Abyssinian speci- 
mens.” . 
The keel of the sternum in Gyparchus has the antero-posterior curve 
along its lower margin, as we find it in Pseudogryphus and Sarcorhamphus 
(Plate XVII, fig. 107, P. californianus); this outline is faint)y imitated by 
Catharista, but in this bird the border is not nearly so thick even in 
proportion. Cathartes has a convexity peculiarly its own, as distin- 
guishing it from others of the family. The sternum is eminently fal- 
conine among the Old World Vultures in its general form and outline. 
Professor Owen, contrasting the relative lengths of the segments of 
the pectoral limb as observed in the class, refers to it as found in the 
“‘powerful Raptorial flyers,” as showing an intermediate and more harmo- 
niously balanced proportion of the several segments. This is the case, 
in a marked degree, with our American Vultures, for here we find al- 
most a perfect condition of relative equipoise among arm, forearm, and 
pinion, not only as regards lengths, but calibers of the interested long 
bones. To place the former property in a more satisfactory manner be- 
fore the reader, we present a table of the lengths of segments of the 
pectoral limb, given in centimeters and fractions of the same, of the 
members of the family under consideration, and add also measurements 
taken from Gyporgeranus and Neophron percnopterus simply for the sake 
of comparison. In all of the long bones the straght line joining the 
points furthest apart in distal and proximal extremities was taken 
