290 
AVES. 
not found in the jjreceding vertebra. The posterior edge of the neural spine 
is grooved at the base. 
The sacrum preserved includes the dorso-sacral vertebra, whose line of 
junction Avith the following ones is distinct, and the solid body formed by 
the coalescence of eight vertebrae, at the end of which it is broken off. The 
sacrum differs from that of the Golden Eagle in having six diapophyses 
given off behind the dorso-sacral, while only five are present in the latter. 
The dorso-sacral differs in shape; its centrum is compressed, and with an 
acute inferior angle, in which the next centrum resembles it. In the Golden 
Eagle, the centrum is wide, and without keel. The sacrum, though nar- 
roAver, is longer than in that species, and maintains its Avidth farther; thus 
it is Avidest at the ninth centrum, while it has already begun to contract in 
the Golden Eagle at the seventh. There are four consecutive caudal ver¬ 
tebrae and a ploAvshare-bone. The former are, as usual, wider than long, 
and have elevated neural spines notched at the extremity. They are, unlike 
those of A . cJmjsaetos, Avithout hypapophyses. The diapophyses are elongate 
and decurved, and have a flattened face on the upper side near the base. 
The plowshare-bone is remarkable for its small size as compared with the 
corresponding bone of the Aquila chnjsaetos. It is not coossified with the 
preceding vertebra, and the hypapophysial fissure is scarcely closed below 
by the opposite halves of that process. The posterior face is divided by a 
median vertical groove from top to bottom, and each half is flared outward, 
each lateral border being convex. The double hypapophysis projects 
dowiiAvard in two straight processes, separated by a notch. A small fora¬ 
men is present opposite the anterior articular face. The distal part of the 
superior ala is broken off. 
Measurements of vertehrce. 
M. 
Length of a cerAucal below... 0.013 
Length with the anterior articular face. . 0. 014 
Greatest Avidth over the vertebral canal. 0. 0175 
Width of the posterior articular facet. 0. 0065 
Depth of the same. 0. 0045 
Width at the base of the neural canal. 0. 0065 
Length of the centrum of the first dorsal from the anterior concavity-- 0.0113 
Width of the same below... 0. 0120 
Depth of the neural canal posteriorly.. 0. 006 
