Haast.—On the Extinct Genus Harpagornis. 67 
breadth, within one inch above the bridge, then retreating again with a gentle 
curve. After forming the outer boundary of the groove, it then terminates on 
the outer side of the canal for the extensor tendon ; thus differing from Aquila, 
where this second ridge reaches only to the middle of the shaft, and does not 
describe such a considerable arc as we observe upon the fossil bone. 
The distal condyles are well curved at their anterior ends, and have a more 
rounded form (which the outer condyle shows most conspicuously) than either 
Aquila or Circus, in which they are more oblong. Moreover, those of the 
recent species stand more in advance of the shaft. 
The inner distal condyle is also more developed in a transverse extent than 
the outer one—a feature also exhibited by Aquila. 
The shaft of the bone, although slightly bent backwards near its proximal 
end, is, however, straighter than in Aquila, but not so straight as that of 
Circus. The fibular ridge is strongly developed. 
Harpagornis assimilis. 
Inches. 
Total length ... ; $i. ONE 
Cireumference at its CHORO, a (ort broken ©) 
Circumference at its distal end 
Circumference of shaft where thinnest EMI LY 
This tibia, although possessing all the main са of the larger 
species, is, when considering its total length, of a somewhat slighter form. I 
observe, however, that the distal condyles are more oblong, agreeing more in 
their shape with the recent species hitherto used for comparison. This is best 
seen in the outer condyle. 
Might this peculiarity not be traced to age, the skeleton of Harpagornis 
moorei doubtless having belonged to a more aged bird than the smaller species? 
Thus the texture of the extremities of the tibia of the former is far more 
compact than in the latter, in which, although well anchylosed, a want of 
solidity is observable. 
FiBuLA. РІ. VIL, Figs. З and 4. 
Amongst the smaller bones obtained from the locality where the principal 
portion of the skeleton of Harpagornis moorei was excavated are a pair of 
fibule, which, on closer examination, proved to belong to that skeleton. Of 
these the right one is the most perfect. It is 4-27 inches long, the distal point 
being broken off. 
The articular head, 0:80 inch long and 0:31 inch broad, is very large and 
posteriorly slightly convex, its anterior edge sloping down at a considerable 
angle, far more than in Aquila or Circus, in which the articulating surface is 
nearly plane, and stands at a right angle to the shaft. The head is also far 
more hollowed out on the inner side than Aquila. 
