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. 



Ha/rpagornis assimilis. 



Inches. 

 Total length ... ... ... ... ... 8-92 



Circumference at its proximal end ... (partly broken away). 

 Circumference at its distal end ... ... ... 3*80 



Circumference of shaft where thinnest ... ... 1*91 



This tibia, although possessing all the main characteristics 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 

 moo7-ei 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. PI. YII., Figs. 3 and 4. 



Amongst the smaller bones obtained from the locality where the principal 

 portion of the skeleton of Harpiagornis moorei was excavated are a pair of 

 fibulae, 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, O'SO 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 riglit angle to the shaft. The head is also far 

 more hollowed out on the inner side than Aquila. 



